Since the
kidneys and heart are closely related, heart problems are relatively
common in CKD cats.
This page covers the three main heart issues you may be faced with:
hypertrophic cardiomyopathy (HCM), congestive heart failure (CHF), and
arterial thromboembolism (a bloodclot to the legs).
Treating the
heart must normally take precedence.
Treating heart conditions can be challenging in CKD cats because it may
put additional strain on the kidneys (and vice versa). Personally, I
would always want to try, because untreated heart problems are generally
much riskier than CKD.
Introduction
These
are the main
heart problems that may be seen in cats:
HCM is the most
commonly seen heart problem in cats, and as it progresses, CHF and ATE may
also occur.
Heart
murmurs and/or a gallop rhythm are possible
symptoms of heart problems in cats. In some cases they turn out to be of minor concern, but their
presence should always lead to further investigation.
How cats cope
with heart problems varies from cat to cat, depending upon the type of
problem, how advanced it is and how well the cat responds to treatment,
but in most cases I would say it is worth trying treatment. Anything that
may be contributing to the heart problems, such as
anaemia,
hyperthyroidism and
hypertension, should be treated — in some cases, this may actually be
all that is necessary. Heart problems caused by hyperthyroidism in
particular may improve or disappear once the hyperthyroidism is under
control. Try to keep stress to a minimum.
Heart
Smart is a helpful site from Cummings Veterinary Medical Center
at Tufts University
The heart and
kidneys work closely together, so it is not unusual to see a heart patient
develop kidney problems and vice versa. In humans there is a syndrome
known as cardiorenal syndrome (CRS), which
Volume overload and cardiorenal syndromes
(2010) Ronco C & Maisel A Congestive Heart Failure16
Supp 1 ppi-iv describes as "disorders of the heart and kidneys whereby
acute or chronic dysfunction in one organ may induce acute or chronic
dysfunction of the other.”
There is
growing interest in the veterinary field in the interaction between the
heart and the kidneys.
Cardiovascular-renal axis disorders in the domestic
dog and cat; a veterinary consensus statement (2015) Pouchelon
JL, Atkins CE, Bussadori C, Oyama MA, Vaden SL, Bonagura JD, Chetboul V,
Cowgill LD, Elliot J, Francey T, Grauer GF, Luis Fuentes V, Sydney Moise
N, Polzin DJ, Van Dongen AM & Van Israël N Journal of Small Animal
Practice56(9) pp537–552 discusses what it terms
cardiovascular-renal disorders (CvRD) in cats and dogs. It states "Cardiovascular-renal
disorders (CvRD) are defined as disease, toxin or drug-induced structural
and/or functional damage to the kidney and/or cardiovascular system,
leading to disruption of the normal interactions between these systems, to
the ongoing detriment of one or both."
Finding the balance in your patients with
cardiovascular and renal disease
(2018) Cook A & Saunders AB Today's Veterinary Practice Mar/Apr
2018 explains more about how the heart and kidneys interact. It says
"Balancing management of patients with concurrent cardiovascular and renal
disease is challenging. You may need to prioritize one organ system above
the other, bearing in mind that overall treatment goals are to maintain
appetite and body condition, decrease clinical signs, and provide a good
quality of life for the patient.'
In most cases, the heart problem must take
precedence (the kidneys may have to take precedence, at least temporarily,
in cats with acute kidney injury and/or a kidney infection or CKD cats who are crashing). Although the treatment for the heart condition may put
additional strain on the kidneys and vice versa, making it difficult to
manage both conditions, it is usually worth trying treatment, because
some cats do well.
Symptoms, Including
Heart Murmurs and Gallop Rhythm
Unfortunately many cats with heart problems are asymptomatic or show very
few symptoms, which can make diagnosis difficult. Therefore if you have not
noticed your cat has heart problems, please do not blame yourself.
Heart disease is difficult to detect in cats
(2012) Canadian Veterinary Medical Association says "Heart disease
has often been described as a silent killer and this is especially true in
cats...Early signs of heart disease in the cat are very easy to miss.
This is because early symptoms are either non-existent or so subtle and
non-specific as to be rarely noticed by owners. To further complicate
matters, cats seem to know their own capabilities and limitations and tend
to restrict their level of activity, which can further mask clinical
signs. Therefore, it is easy to miss the early signs of feline heart
disease." This was certainly true of my cat, whose only symptom was
weight loss for which my vet could not find an obvious cause, so we
assumed it was age-related (she was sixteen years old).
It
does not help that some of the possible symptoms are similar to those of
CKD, including lack of appetite, lethargy and vomiting. Some cats have a
cardiac cough, though this is more common in cases of congestive heart
failure. Other symptoms include.
If you suspect
heart problems, in many cases you can wait a day or two to see the vet
(though I would get my cat in as soon as I could during normal office
hours).
However, if your cat cannot walk or has a leg that is cold to the touch,
it is a medical emergency and you should seek veterinary help immediately.
If your cat
appears to be having trouble breathing, i.e. an increase in breathing
effort or breathing rate,
I would take your cat to the vet as soon as possible, particularly if s/he
is breathing with the mouth
open.
Fast Heart Rate (Tachycardia) and High
Respiration Rate
One possible
sign of heart problems is a fast heart rate. In the case of cats visiting
the vet, a fast heart rate may be caused by stress ("white coat
syndrome"), but if your cat's heart seems to be beating very fast when
resting at home, I would seek veterinary advice.
You may also
see faster breathing (respiration).
Respirations
are normally measured when the cat is resting or asleep. They will always be more
frequent when the cat is awake. Breathing in and out once counts as one
breath.
Surprisingly,
there appears to be little agreement on what is normal in terms of pulse
and respiration for cats, as the table below shows:
Source
Pulse (beats per minute)
Respirations per minute
Merck Veterinary Manual
120 - 140
Veterinary Drug Handbook
100 - 120
(old cats)
The Cornell Book of Cats
160 - 240
20 - 30
The Pill Book Guide to Medication for Your Dog and
Cat
Feline cardiology (2011) Côté E,
MacDonald KA, Meurs KM & Sleeper MM Wiley-Blackwell gives reference
ranges for heart and respiration rates for cats and kittens both at home
and at the vet's (where higher rates may be seen in stressed cats).
Sleeping and resting respiratory rates in healthy
adult cats and cats with subclinical heart disease
(2014)
Ljungvall I, Rishniw M, Porciello F, Häggström J & Ohad D Journal of
Feline Medicine and Surgery 16(4) pp281-290 states "Our data
suggest that EN and AH cats [apparently healthy cats with normal heart
ultrasound results] without clinical evidence of heart disease, and cats
with known subclinical heart disease generally have stable SRR [sleeping
respiratory rate] <30 breaths/min in the home environment, and slightly
higher and more variable RRR [resting respiratory rate] when measured at
home by clients." The study concludes "Cats with SRRmean >30
breaths/min and cats with multiple SRR measurements >30 breaths/min likely
warrant additional evaluation."
(2001)
Hughes D Presentation to theWorld Small Animal Veterinary
Association World Congress is rather technical but may still be
of use.
Some people
whose cats have heart problems learn how to use a pediatric stethoscope on
their cats. Even if you don't do this, ask your vet for guidance on what
is normal for your cat.
Weight Loss and Muscle Loss (Cardiac
Cachexia)
Cats with heart
failure may also exhibit loss of weight, in particular lean body mass. The
loss of lean body mass (muscle) associated with heart disease is known as
cardiac cachexia.
Cachexia and sarcopenia: emerging syndromes of
importance in dogs and cats (2012) Freeman LM Journal of
Veterinary Internal Medicine26 pp3-17 has a photograph of a
dog with this symptom.
One of my cats had heart disease (HCM) and her only
symptom was weight loss.
Heart Murmurs
A heart murmur
occurs when blood flows through the heart turbulently rather than
smoothly. It is not the same as an arrhythmia.
Heart murmurs in cats (2010) Yuill C has
a helpful overview of heart murmurs.
In most cases the vet will detect a heart murmur when listening
to the heart with a stethoscope (auscultation).
Heart murmurs
are graded from 1 to 6 depending upon their severity:
Grade 1
Lowest level at which a murmur can be heard but may
only be detectable when the cat is frightened, stressed or in pain.
Grade 2
Always present, regardless of the cat's emotional
state, but it is faint and often only audible in certain areas of the
heart.
Grade 3
Can be heard at once by the vet.
Grade 4
Can also be heard at once, and there is also a
vibration known as a thrill.
Grade 5
This is a very loud murmur.
Grade 6
An extremely loud murmur
which is often audible without a stethoscope.
Heart murmurs in dogs and cats
(2018) Rishniw M Veterinary Partner has information on
heart murmurs and allows you to listen to a normal heart and to one with a
murmur.
Heart murmurs
may or may not need treatment, depending upon their cause and their
severity. Both
anaemia and
hyperthyroidism may cause a heart murmur
which disappears following treatment of the underlying problem. Cats with
hypertension may have a heart murmur.
Blood pressure in small animals part 2:
hypertension — target organ damage, heart and kidney
(2009) Carr AP & Egner BE
European Journal of Companion Animal
Practice19(1) pp1-5 states that "A
new murmur or gallop rhythm should always lead to a blood pressure
measurement."
However, heart murmurs are not always a
sign of a problem (such murmurs are labelled benign, physiologic or innocent heart
murmurs).
Management of incidentally detected heart murmurs in
dogs and cats (2015) Côté E, Edwards NJ,
Ettinger SJ, Luis Fuentes V,
MacDonald KA, Scansen
BA, Sisson DD,
Abbott JA; Working Group of the American
College of Veterinary Internal Medicine Specialty of Cardiology on
Incidentally Detected Heart Murmurs Journal of the American
Veterinary Medical Association246(10) pp1076-88 says that it
can be difficult to determine whether a murmur is cause for concern or
benign.
In
Assessment of the prevalence of heart murmurs in
overtly healthy cats (2004)
Côté
E, Manning AM, Emerson D, Laste NJ, Malakoff RL & Harpster NK
Journal of the American Veterinary Medical Association225
pp384-388 22 of 103 apparently healthy cats were found to have a heart
murmur but only four of the 22 turned out to have HCM.
Prevalence of cardiomyopathy in apparently healthy
cats (2009) Paige CF, Abbott JA, Elvinger F & Pyle RL
Journal of the American Veterinary Medical Association234(11)
pp1398-1403 found that "in apparently healthy cats, detection of a heart
murmur is not a reliable indicator of cardiomyopathy."
The grade of the murmur is also not in itself a cause for concern.
Heart murmurs and heart disease (2013)
Cats Protection says "The grade of murmur heard does not necessarily mean
heart disease is more or less severe, or even present...On its own, a
heart murmur is not a reliable indicator of heart disease or function and
is commonly found in healthy cats."
Even if a
murmur is determined to be benign, it is important to monitor it.
Other tests may also be performed, such as x-rays or
ultrasound.
Some cats have heart murmurs because they have
hypertrophic cardiomyopathy.
International collaborative study to assess
cardiovascular risk and evaluate long-term health in cats with preclinical
hypertrophic cardiomyopathy and apparently healthy cats. The REVEAL study
(2018) Fox PR, Keene BW, Lamb K, Schober KA, Chetboul V, Luis Fuentes V,
Wess G, Payne JR, Hogan DF, Motsinger-Reif A, Häggström J, Trehiou-Sechi
E, Fine-Ferreira DM, Nakamura RK, Lee PM1, Singh MK, Ware WA, Abbott JA,
Culshaw G, Riesen S, Borgarelli M, Lesser MB, Van Israël N, Côté E, Rush
JE, Bulmer B, Santilli RA, Vollmar AC, Bossbaly MJ, Quick N, Bussadori C,
Bright JM, Estrada AH, Ohad DG, Fernández-Del Palacio MJ, Lunney Brayley
J, Schwartz DS, Bové CM, Gordon SG, Jung SW, Brambilla P, Moïse NS,
Stauthammer CD, Stepien RL, Quintavalla C, Amberger C, Manczur F, Hung YW,
Lobetti R, De Swarte M, Tamborini A, Mooney CT, Oyama MA, Komolov A, Fujii
Y, Pariaut R, Uechi M, Tachika Ohara VY Journal of Veterinary Internal
Medicine 32(3) pp930-943 followed 1008 cats with HCM for up to
fifteen years. It found that 82% of the cats with HCM had heart murmurs
but so did 46% of healthy cats, though healthy cats were more likely to
have a lower grade murmur (grades 1 and 2).
Cardiomyopathy prevalence in 780 apparently healthy
cats in rehoming centres (the CatScan study)
(2015) Payne JR, Brodbelt DC & Luis
Fuentes V Journal of Veterinary Cardiology17(Suppl 1) ppS244–25 looked at 780
apparently healthy cats and found that "Heart
murmur prevalence was 40.8% (95% confidence interval (CI) 37.3-44.3%),
70.4% of which were considered functional...The positive predictive value
of a heart murmur for indicating HCM was 17.9-42.6% (higher in old cats),
and the negative predictive value was 90.2-100% (higher in young cats)."
Prevalence of echocardiographic evidence of cardiac
disease in apparently healthy cats with murmurs
(2011) Nakamura RK, Rishniw M, King MK & Sammarco CD Journal of Feline
Medicine & Surgery13 pp266-71, found that 53% of the
apparently healthy cats with heart murmurs in their study had
cardiomyopathy, so concluded "identification of a heart murmur on
routine physical examination in apparently healthy cats warrants further
investigation."
Gallop Rhythm
A gallop rhythm may be heard when listening to the heart
with a stethoscope (auscultation). Normally when you listen to the heart
there are two sounds (dub-dub) but in cats with a gallop rhythm there are
three (dub-dub-dub).
Gallop rhythms
may also be heard in cats as they age.
Aging in cats: common physical and functional
changes (2016) Bellows J, Center S, Daristotle L, Estrada AH,
Fickinger EA, Horwitz DF, Lascelles BDX, Lepine A, Perea S, Scherk M &
Shoveller AK Journal of Feline Medicine & Surgery18
pp533–550 states "Although gallop
rhythms are auscultated in many cats
with myocardial disease,
it is also noteworthy that
older feline patients (>10 years
of age) may occasionally
have a
gallop rhythm that is related to
an aging, stiff ventricle, in the
absence of significant cardiovascular disease."
Subtle indications of pre-clinical heart disease in
cats (2016) Nguyenba T MedVet
Medical & Cancer Centers for Pets says "Even with heart disease severe
enough to cause CHF, only half of these cats will exhibit heart
murmurs. Finding other auscultable abnormalities, such as gallop sounds
and arrhythmias, may be of great benefit, as the addition of these
findings may improve sensitivity and specificity for detecting heart
disease in cats."
Thus
a gallop
rhythm may or may not be a sign of problems. Nevertheless, I would always
ask for additional checks to be performed on a cat with one.
Feline hypertrophic cardiomyopathy, hypertension and
hyperthyroidism (2010) Meurs K
CVC in Kansas City (Proceedings) says "A
gallop rhythm may be ausculted indicating abnormal left ventricular
filling. Since asymptomatic cats may be affected, we recommend screening
with an echocardiogram if a murmur or gallop is ausculted."
Diagnosis
Your vet may
suspect heart problems based on the above signs and symptoms, and may then
use some of the diagnostic methods listed below.
Although many
of these tests can be performed by your vet, if there is a strong
suspicion of heart problems I would ask for a referral to a veterinary
cardiologist if possible, in order to obtain an accurate diagnosis and a personalised treatment
plan.
Cavalier Health has details of veterinary
cardiologists in the USA, Canada and the UK.
Your vet may
initially use a stethoscope to check your cat’s heart. This is known as
auscultation. Your vet may hear a
heart murmur or a
gallop rhythm.
Do not panic if
this is the case.
Aging in cats: common physical and functional
changes (2016) Bellows J, Center S, Daristotle L, Estrada AH,
Fickinger EA, Horwitz DF, Lascelles BDX, Lepine A, Perea S, Scherk M &
Shoveller AK Journal of Feline Medicine & Surgery18
pp533–550 states "Multiple studies in
apparently healthy cats and cats with
cardiomyopathy have repeatedly shown, however, that cardiac auscultation
is insensitive for detecting
underlying cardiac disease."
Your vet may
therefore offer to run additional tests.
X-Rays
X-rays
can be very useful for cats with breathing issues (breathing fast or heavily).
This is the best way to check for and diagnose
pleural effusion,
pulmonary
oedema or
ascites, all commonly seen in cases of
congestive heart failure.
Cardiovascular-renal axis disorders in the domestic
dog and cat; a veterinary consensus statement (2015) Pouchelon
JL, Atkins CE, Bussadori C, Oyama MA, Vaden SL, Bonagura JD, Chetboul V,
Cowgill LD, Elliot J, Francey T, Grauer GF, Luis Fuentes V, Sydney Moise
N, Polzin DJ, Van Dongen AM & Van Israël N Journal of Small Animal
Practice56(9) pp537–552 states "Thoracic radiography is
recommended to assess the presence or absence of congestive heart failure."
Pulmonary pattern recognition
(2009) Kunze C & Lo W Idexx Digital Download2(3) has
photos of x-rays, including one of a cat with congestive heart failure.
X-rays are of limited use in diagnosing
HCM, the most common heart problem in cats.
Feline hypertrophic cardiomyopathy, hypertension and
hyperthyroidism (2010) Meurs K
CVC in Kansas City (Proceedings) says "Radiographs
may be useful to evaluate for cardiomegally, chamber enlargement patterns,
and evidence of heart failure, but are NOT diagnostic for the specific
form of feline heart disease."
Although x-rays cannot be used to diagnose HCM in cats, cats with HCM often have a "valentine"-shaped heart,
where x-rays show that the heart is enlarged at the bottom.
Associations between ‘valentine’ heart shape, atrial
enlargement and cardiomyopathy in cats (2015) Winter MD, Giglio
RF, Berry CR, Reese DJ, Maisenbacher HW & Hernandez JA
Journal of Feline Medicine & Surgery17(6) pp447-452 found
that 82% of the cats in the study with this finding did have
cardiomyopathy, but only 18% had hypertrophic cardiomyopathy, and some
healthy cats had this finding.
Echocardiogram
(Ultrasound)
An ultrasound
of the heart, ideally with Doppler colour flow imaging, is the most
accurate way to diagnose hypertrophic
cardiomyopathy (HCM).
ACVIM consensus statement guidelines for the
classification, diagnosis, and management of cardiomyopathies in cats
(2020) Luis Fuentes V, Abbott J, Chetboul V, Côté E, Fox PR,
Häggström J, Kittleson MD, Schober K & Stern JA
Journal of Veterinary Internal MedicineEpub ahead of print
state "Echocardiography is the gold standard test for diagnosis of
cardiomyopathies in cats."
Cardiovascular-renal axis disorders in the domestic
dog and cat; a veterinary consensus statement (2015) Pouchelon
JL, Atkins CE, Bussadori C, Oyama MA, Vaden SL, Bonagura JD, Chetboul V,
Cowgill LD, Elliot J, Francey T, Grauer GF, Luis Fuentes V, Sydney Moise
N, Polzin DJ, Van Dongen AM & Van Israël N Journal of Small Animal
Practice56(9) pp537–552 states "Renal imaging is recommended
to improve diagnosis, prognosis and guide potential therapies in CvRD.
Conventional abdominal radiographs and ultrasound are recommended to help
detect morphological abnormalities and determine underlying aetiology."
If you cannot
visit a veterinary cardiologist, it is sometimes possible for your own vet
to perform the ultrasound and send the images through to a veterinary
cardiologist for interpretation. Alternatively,
The use of focused cardiac ultrasound to screen for
occult heart disease in asymptomatic cats (2019) Loughran KA,
Rush JE, Rozanski EA, Oyama MA, Larouche-Lebel E & Kraus MS Journal of
Veterinary Internal Medicine 33 pp1892-1901 reports on a new
focused cardiac ultrasound (FCU) protocol for vets in general practice to
help them assess cats who might have heart disease. After a small amount
of training, the general vets in the study were able to diagnose heart
disease in 93% of cats with moderate heart disease and in 100% of cats
with severe heart disease.
NTproBNP Blood Tests
NT-proBNP
is a peptide. Levels of NT-proBNP increase in the bloodstream when the walls of the heart are under
strain and thus stretch, as may happen in heart failure.
NTproBNP Blood Test
NTproBNP test is a blood test available
from IDEXX Laboratories which it states "can be clinically useful as an initial screening test for
cats with suspected cardiac disease."
The normal range is usually 0 - 100
pmol/L.
The
test is also available as a
SNAP proBNP test. SNAP tests are not
always as accurate as laboratory tests but can be
performed quickly in-house by vets, and a negative SNAP NTproBNP test is
considered to be reliable..
IDEXX compared the accuracy of the SNAP
test with the NTproBNP test and found that the SNAP test was 99.5% in agreement with
the standard test if levels were below
100 pmol/L(i.e. normal) and 95% in agreement if levels were above
270 pmol/L.
Effect of feline characteristics on plasma
N-terminal-prohormone B-type natriuretic peptide concentration and
comparison of a point-of-care test and an ELISA test (2020)
Hanås S, Holst BS, Höglund K, Häggström J, Tidholm A & Ljungvall I
Journal of Veterinary Internal Medicine Epub ahead of print found that
male cats tend to have higher levels of ProBNP and
that the SNAP test appears to be as accurate as the laboratory
test.
IDEXX
provides an
algorithm for using the SNAP test. If the test is positive (i.e. over 100
pmol/L), it is
recommended that you should have the full NTproBNP test run in the
laboratory.
NTproBNP Blood Tests Accuracy
The presence of
other illnesses may affect the results of these tests.
NT-ProBNP testing in cats
(2014)
Gordon SG Cardiac Education Group mentions
that NTproBNP is cleared by the kidneys, so damaged kidneys could make
NTproBNP levels look higher than they actually are. In addition,
Circulating natriuretic peptide concentrations in
hyperthyroid cats(2012) Menaut P, Connolly DJ, Volk A, Pace C,
Luis Fuentes V, Elliott J & Syme H Journal of Small Animal Practice53(12) pp673-8 found that NT-proBNP levels are
elevated in cats with
hyperthyroidism. It concluded that "Thyroid status should be
taken into account when interpreting NT-proBNP concentrations in cats."
There is some
debate as to the accuracy of the test.
NT-proBNP measurement fails to reliably identify
subclinical hypertrophic cardiomyopathy in Maine Coon cats
(2011) Singh MK, Cocchiaro MF, Kittleson MD Journal of Feline
Medicine & Surgery 12 p942, found that "56%
of cats with severe disease in this study would have been considered
normal based on a NT-proBNP concentration; the sensitivity for diagnosing
severe disease was only 44% (at a cutoff of ≤100 pmol/l). For any other
condition less than severe HCM, the measurement of NT-proBNP concentration
was found to be insensitive. Cats with equivocal and moderate disease were
not identified by this assay."
The higher the reading, the more likely it is to be accurate.
This test may
be of some use as a starting point to check if the cause of your cat's
symptoms is cardiac or non-cardiac, but I would not
rely on it alone to diagnose heart disease, particularly not in a cat
known to have CKD.
Cardiac
Troponin I
Cardiac troponin I is an intracellular
protein. High levels in humans indicate a strong possibility of a heart
attack (myocardial infarction).
Cardiac troponin I is not routinely measured in cats, but may be of some
use in diagnosing congestive heart failure. See
below for more about
this.
H
olter
Monitors
Holter monitors are used to monitor the heart over a period of time in
order to detect problems that are not always or frequently apparent. They
are worn by humans for around 1-3 days, occasionally for longer.
Ambulatory electrocardiogram recordings in cats with
primary asymptomatic hypertrophic cardiomyopathy (2017) Hanås
S, Tidholm A & Holst BS Journal of Feline Medicine and Surgery
19(2) pp158-164 looked at the use of holter monitors in cats with HCM
but who showed no symptoms. The study found few irregularities during the
use of holter monitors in the cats with asymptomatic HCM, and states that
there were few differences between these cats and healthy cats.
Exploring holter monitoring in cats with HCM
(2018) Winn Feline Foundation is funding research into the
use of holter monitors in cats to see if it helps identify HCM cats at
risk of sudden death. The cats wear the holter monitors at home for three
days and seem to tolerate them well. Results to date have found that 71%
of the cats in the study had severe arrhythmias that are often linked to
sudden death. This was a far higher percentage than expected.
Cardiomyopathy
means disease of the heart muscle. There are several types of
cardiomyopathy seen in cats, including:
hypertrophic cardiomyopathy (HCM)
restrictive cardiomyopathy (RCM)
dilated cardiomyopathy (DCM)
arrhythmogenic right ventricular
cardiomyopathy (ARVC)
HCM
is the most common form of heart disease in cats, and the only one covered
on this page.
University of California at Davis
(2016) says it "was recently reported to affect a startling one in
seven cats." The study referred to,
Cardiomyopathy prevalence in 780 apparently healthy
cats in rehoming centres (the CatScan study)
(2015) Payne JR, Brodbelt DC & Luis
Fuentes V Journal of Veterinary Cardiology17(Suppl 1) ppS244–257, found that "The
prevalence of HCM was 14.7%...The
HCM prevalence increased with age." It is also more
common in male cats.
In hypertrophic cardiomyopathy, the left ventricle of
the heart, which pumps blood through the aorta, the body's largest
artery, is enlarged (hypertrophic) with no obvious cause. This
prevents the ventricle from working properly, adversely affecting heart
function as a whole. Possible complications include:
death. Cats
with HCM may die suddenly, often before the disease has even been
diagnosed. In fact, HCM is the top cause of sudden death in cats.
The other types of cardiomyopathy are rare in cats.
Cardiomyopathy prevalence in 780 apparently healthy
cats in rehoming centres (the CatScan study)
(2015) Payne JR, Brodbelt DC & Luis
Fuentes V Journal of Veterinary Cardiology17(Suppl 1) ppS244–257, found that "The
prevalence of...other cardiomyopathies [is] 0.1% (95% CI 0.0-0.7%)." Dilated cardiomyopathy may be caused by a lack of
taurine in the diet, and is very rare since cat food manufacturers
began supplementing commercial cat foods with appropriate amounts of
taurine.
Feline cardiomyopathies - an update
(2009) French A Presentation to the World Small Animal Veterinary
Association World Congress describes the various types of
cardiomyopathy.
Cats who are predisposed to
cardiomyopathy (e.g. because of their breed) but who exhibit no
evidence of heart disease
B
Cats with cardiomyopathy but without symptoms. Stage B is divided into
stages B1 and B2 and atrial size helps determine whether B1 or B2. The
more severe the left atrial (LA) enlargement, the higher the risk of
CHF and ATE:
Another factor is anaemia.
Hypertension, left ventricular hypertrophy and
chronic kidney disease (2011) Taddei S, Nami R, Bruno RM,
Quatrini I & Nuti R Heart Failure Reviews16(6) pp615-20
says of human patients "Left ventricular hypertrophy (LVH) is a
cardiovascular complication highly prevalent in patients with chronic
kidney disease (CKD) and end-stage renal disease... In particular, the
correction of anemia with erythropoietin in CKD patients is advantageous,
since it determines LVH reduction."
However, it is
also possible for a cat to have HCM without any associated disease.
Hypertrophic Cardiomyopathy Genetic Link
HCM appears to be a genetic problem in certain breeds, such as Maine
Coons, Persians, Ragdolls, Birmans and Norwegian Forest Cats. In fact, the
University of California Davis uses Maine Coons to study feline heart
disease since it is so common in this breed, where it is an inherited
autosomal dominant trait.
Familial cardiomyopathy in Norwegian Forest Cats
(2015) Maerz, Wilkie L, et al. Journal of Feline
Medicine and Surgery17 (8) pp681-691 looked at
Norwegian Forest Cats in the UK and concluded "Pedigree data analysis from
871 NFCs was supportive of a familial cardiomyopathy in this breed."
Birman cats are also prone to developing cardiomyopathy and the Royal
Veterinary College has been investigating this. The researchers have found
that around 10% of Birman cats in Europe have cardiomyopathy, with around
7% having HCM. 82% of the cats with HCM were male. Heart murmurs are more common in Birmans with HCM, so any
Birman cat with a heart murmur should have an ultrasound performed.
I lost my Chinchilla kitten to HCM when he was nine months old. He
collapsed and died at the vet's, five weeks after we adopted him, and just
a few months after my 16 year old Chinchilla collapsed and died at the vet's. She had been diagnosed with HCM two weeks earlier by a veterinary
cardiologist and was at the vet's for a recheck to see if the medications
were helping her.
Seeking answers on HCM in Persian cats
(2017) Winn Feline Foundation reports on research into Persian cats
and HCM but states that studies to date have not been able to identify a
single variant for Persians.
If
your cat has HCM caused by hyperthyroidism or hypertension (secondary
HCM), it is essential to treat these conditions.
Survival in cats with primary and secondary
cardiomyopathies (2016) Spalla I, Locatelli C, Riscazzi G,
Santagostino S, Cremaschi E & Brambilla P Journal of Feline Medicine
and Surgery18(6) pp501-509 states "Secondary CMs are more
benign conditions, but if the primary disease is not properly managed, the
prognosis might also be poor in this group of patients."
Similarly, if your cat has anaemia, you must take steps to control it.
Hypertension, left ventricular hypertrophy and
chronic kidney disease (2011) Taddei S, Nami R, Bruno RM,
Quatrini I & Nuti R Heart Failure Reviews16(6) pp615-20
says of human patients "Left ventricular hypertrophy (LVH) is a
cardiovascular complication highly prevalent in patients with chronic
kidney disease (CKD) and end-stage renal disease... In particular, the
correction of anemia with erythropoietin in CKD patients is advantageous,
since it determines LVH reduction."
Otherwise HCM cannot be
cured but it can often be controlled with medications. Unfortunately many
drugs which help the heart condition put strain on the kidneys, so if your
cat has both heart disease and CKD, discuss which drug to use with your
vet (preferably a veterinary cardiologist).
Even if your
cat appears stable once medication has begun, it is a good idea to have an
ultrasound examination of your cat's heart undertaken once every year (or
more regularly if your cardiologist advises it) and to review medication
at that time if appropriate.
Some vets
choose to treat asymptomatic cats, whilst others choose to wait.
Effect of treatment with atenolol on 5-year
survival in cats with preclinical (asymptomatic) hypertrophic
cardiomyopathy (2013) Schober KE,
Zientek J, Li X,
Luis Fuentes VL &
Bonagura JD Journal of Veterinary Cardiology 15
pp93-104 looked at the effects of giving heart medication to
asymptomatic HCM cats. The cats who were medicated were given
atenolol (a beta
blocker, though some of them also received enalapril (an
ACE inhibitor), or clopidogrel. The study states "There was no
significant difference in all-cause mortality (P = 0.729) and
cardiac mortality (P = 0.897) between cats with HCM treated or
untreated with atenolol. Age and left atrial size at diagnosis were
the only predictors of 5-year outcome."
ACVIM consensus statement guidelines for the
classification, diagnosis, and management of cardiomyopathies in cats
(2020) Luis Fuentes V, Abbott J, Chetboul V, Côté E, Fox PR,
Häggström J, Kittleson MD, Schober K & Stern JA
Journal of Veterinary Internal MedicineEpub ahead of print say
"Cats with stage B1 cardiomyopathy are considered at low risk of CHF or
ATE, and in general treatment is not recommended," but they recommend
treating from Stage B2 onwards.
Atenolol
(Tenormin) is a type of beta blocker commonly used in the USA.
In the UK, a similar drug called propranolol (Inderal) may be used.
Pharmacokinetics of atenolol in clinically normal
cats (1996) Quinones M, Dyer DC, Ware WA & Mehvar R American
Journal of Veterinary Research 57(7) pp1050-3 discusses the
effects of atenolol on cats.
Beta blockers
are often used to slow a fast heart rate (tachycardia).
Feline hypertension: Part 1
(2012) Atkins C says "Tachycardia not only contributes to hypertension
but is also harmful to the cardiovascular system; persistent tachycardia
should be managed with atenolol."
Pet Place has an overview of atenolol and
states "Reducing the heart rate and strength of heart muscle contraction can be
beneficial to some cats and dogs with the condition called hypertrophic
cardiomyopathy, especially when the heart muscle contracts so vigorously
it obstructs the path of blood."
The use of beta
blockers may be recommended for cats with HCM even if it is sub-clinical,
i.e. the cat is showing no symptoms as yet.
Effect of atenolol on heart rate, arrhythmias, blood
pressure, and dynamic left ventricular outflow tract obstruction in cats
with subclinical hypertrophic cardiomyopathy (2015) Jackson
BL, Adin DB, Lehmkuhl LB Journal of Veterinary Cardiology17
S296-S305 looked at using atenolol in cats with mild sub-clinical HCM. It
concludes "Atenolol decreases HR, murmur grade, and LVOT obstruction, and
to a lesser degree, frequency of ventricular ectopy, in cats with
subclinical HCM. Further studies are needed to determine if sudden cardiac
death or long-term outcome is influenced by atenolol administration."
Plumb's
Veterinary Drug Handbook states "While atenolol has been used in cats with
preclinical hypertrophic cardiomyopathy its use is controversial."
ACVIM consensus statement guidelines for the
classification, diagnosis, and management of cardiomyopathies in cats
(2020) Luis Fuentes V, Abbott J, Chetboul V, Côté E, Fox PR,
Häggström J, Kittleson MD, Schober K & Stern JA
Journal of Veterinary Internal MedicineEpub ahead of print say
"atenolol has not been shown to have any effect on the 5-year survival
rate in cats with subclinical HCM," but go on to say it may be worth
considering in cats with ventricular ectopy with HCM.
Some vets believe that beta blockers should not be begun in cats with HCM who also have
congestive
heart failure.
Feline hypertrophic cardiomyopathy, hypertension and
hyperthyroidism(2010) Meurs K
CVC in Kansas City (Proceedings) says "atenolol
should never be started in cats with congestive heart failure (CHF)." Plumb's
Veterinary Drug Handbook states "Atenolol may cause increased morbidity in cats with
hypertrophic cardiomyopathy with accompanying left-sided CHF."
Pet Place
says of atenolol "The typical dose administered to cats is 1 mg per pound (2 mg/kg)
once daily. The total daily dose in cats is often 6.25 to 12.5 mg once or
twice daily." It does also say "Frequently, atenolol is given with other
drugs, especially in pets undergoing treatment for heart failure or
arrhythmias (abnormal heart rhythm). In these situations, a lower initial
dose may be prescribed."
Those I hear
from tend to give 6.25mg (a quarter of a 25mg tablet) twice a day.
However, some give a lower dose, especially if they are also giving other
heart medications.
If you are
giving 0.27mg, you would need to divide the smallest tablet available
(25mg) into a hundred. I can't see how this is possible, I think you would
have to have it compounded into cat-sized dosages instead.
Beta Blockers: Side Effects
Side effects
are uncommon, but may include lethargy, diarrhoea and hypotension (low
blood pressure). Contact your vet if you see these symptoms or if your cat
becomes breathless or develops a cough.
If you stop the
medication after giving it for a while, Plumb's Veterinary Drug Handbook
recommends doing so gradually, because stopping it abruptly may make
symptoms worse.
ACE inhibitors prevent the conversion of a hormone called angiotensin I into
another hormone called angiotensin II, the role of which is to constrict
blood vessels. This helps the blood vessels relax, which makes it easier for the heart to pump blood through the body.
ACE inhibitors are a popular treatment for HCM. This
may change following publication of a recent study,
Evaluation of benaepril in cats with heart disease
in a prospective, randomized, blinded, placebo-controlled trial
(2019) King JN, Martin M, Chetboul V, Ferasin L, French AT,
Strehlau G, Seewald W, Smith SGW, Swift ST, Roberts SL, Harvey AM, Little
CJL, Caney SMA, Simpson KE, Sparkes AH, Mardell EJ, Bomassi E, Muller C,
Sauvage JP, Diquélou A, Schneider MA, Brown LJ, Clarke DD & Rousselot JF
Journal of Veterinary Internal Medicine33(6) pp2559-2571,
which found that they seemed to be of limited value.
ACVIM consensus statement guidelines for the
classification, diagnosis, and management of cardiomyopathies in cats
(2020) Luis Fuentes V, Abbott J, Chetboul V, Côté E, Fox PR,
Häggström J, Kittleson MD, Schober K & Stern JA
Journal of Veterinary Internal MedicineEpub ahead of print say
of this study "benazepril had no effect on time to treatment
failure compared to placebo in a randomized placebo-controlled study that
included cats with subclinical heart disease."
In the
USA you will probably be offered enalapril, the trade name of which is
Enacard.
Mar
Vista Vet has information and cautions on the use of
enalapril,
including when using it in conjunction with diuretics such as furosemide
(known as frusemide in the UK) (see
below).
In the UK, Europe and Australia you are more likely to
be offered benazepril. Benazepril (under the name of Fortekor) is licensed for
the treatment of CKD in cats in the UK, Europe and Australia, even for
cats without heart disease.
It is not
unusual for cats suffering from
congestive heart failure to be given both an ACE inhibitor and a
diuretic, though in such situations furosemide is a safer choice than
spironolactone.
You
should be careful if you are using ACE inhibitors at the same time as
potassium supplements, because they may cause potassium levels to
become dangerously high.
More detailed information about ACE inhibitors can be
found on
the
Proteinuria page.
Angiotensin II Receptor Blockers (ARBs)
Angiotensin II receptor blockers (ARBs) are heart
medications which work in a slightly different way to
ACE inhibitors.
Angiotensin II is a hormone, the role of which is to
constrict blood vessels. This type of medication works by blocking the
receptor to which angiotensin II attaches, thus relaxing the blood
vessels, which in turn helps to reduce blood pressure and therefore
reduces the work that the heart has to perform to pump blood through the
body. These medications are sometimes referred to as angiotensin II
receptor antagonists.
In human medicine ARBs tend to be used when ACE
inhibitors cannot be used for some reason. I have not heard from many
people using them for cats with heart disease, though like ACE inhibitors,
they may be prescribed for cats with proteinuria.
More detailed information about ARBs can be
found on
the Proteinuria page.
Calcium Channel Blockers
Calcium channel
blockers work by slowing the passage of calcium into muscle cells; this
makes muscle in the blood vessels relax, so the blood vessels open wider.
One member of the calcium channel blocker family,
amlodipine, is
generally considered to be the best choice for controlling hypertension in cats.
Another calcium
channel blocker,
diltiazem,
may be used in the treatment of HCM in cats. I do not hear
from many people using diltiazem but if you are using it in a CKD cat, you
may need to reduce the dose.
Drugs
mentions that diltiazem may interact with beta blockers or
cisapride
(a treatment for severe constipation), which can lead to increased side
effects.
Cimetidine or
ranitidine may strengthen the effects of diltiazem.
Clopidogrel
Clopidogrel is an antithrombotic treatment, i.e. used to thin the cat's
blood and reduce the risk of blood clots forming. Previously clopidogrel
was used primarily in cats who had experienced an
arterial thromboembolism, but
ACVIM consensus statement guidelines for the
classification, diagnosis, and management of cardiomyopathies in cats
(2020) Luis Fuentes V, Abbott J, Chetboul V, Côté E, Fox PR,
Häggström J, Kittleson MD, Schober K & Stern JA
Journal of Veterinary Internal MedicineEpub ahead of print say
"Cats with stage B2 HCM have an increased risk of developing
CHF or
ATE.
Primary prevention of ATE in cats with subclinical cardiomyopathy has not
been studied, but thromboprophylaxis is recommended when known risk
factors for ATE are present...Clopidogrel therefore is recommended in cats
considered at risk of ATE."
Pimobendan is a medication belonging to the
inodilator family of medications. It has been successfully used in cats
with congestive heart failure secondary to HCM, but its use in cats with
HCM only is considered
controversial.
Pimobendan is discussed in more detail in the congestive heart
failure section below.
University of California at Davis
(2016) reports on the study and "hopes to conduct a clinical trial
in the near future, which could determine if MYK-461 has the potential to
become the accepted protocol for care of cats with HCM."
Hypertrophic Cardiomyopathy Prognosis
HCM is a very serious disease which can have serious consequences.
International collaborative study to assess
cardiovascular risk and evaluate long-term health in cats with preclinical
hypertrophic cardiomyopathy and apparently healthy cats. The REVEAL study
(2018) Fox PR, Keene BW, Lamb K, Schober KA, Chetboul V, Luis Fuentes V,
Wess G, Payne JR, Hogan DF, Motsinger-Reif A, Häggström J, Trehiou-Sechi
E, Fine-Ferreira DM, Nakamura RK, Lee PM1, Singh MK, Ware WA, Abbott JA,
Culshaw G, Riesen S, Borgarelli M, Lesser MB, Van Israël N, Côté E, Rush
JE, Bulmer B, Santilli RA, Vollmar AC, Bossbaly MJ, Quick N, Bussadori C,
Bright JM, Estrada AH, Ohad DG, Fernández-Del Palacio MJ, Lunney Brayley
J, Schwartz DS, Bové CM, Gordon SG, Jung SW, Brambilla P, Moïse NS,
Stauthammer CD, Stepien RL, Quintavalla C, Amberger C, Manczur F, Hung YW,
Lobetti R, De Swarte M, Tamborini A, Mooney CT, Oyama MA, Komolov A, Fujii
Y, Pariaut R, Uechi M, Tachika Ohara VY Journal of Veterinary Internal
Medicine 32(3) pp930-943 followed 1008 cats with HCM for up to
fifteen years. It found that 24.2% of cats with HCM developed
congestive heart failure and 11.6% developed
arterial thromboembolism (blood clot in the legs); some cats
developed both.
Talking of the same study,
Feline hypertrophic cardiomyopathy: five year
outcomes and risk assessment (2018) Winn Feline Foundation
states "Risk assessed at 1, 5, and 10 years after study-entry showed that
for the total population of [cats] with hypertrophic cardiomyopathy, risk
for developing
CHF was approximately 1 in 14, 1 in 5, and 1 in 4, respectively, while
risk for developing
ATE was
approximately 1 in 30, 1 in 10 and 1 in 10, respectively."
This is not to say there is no hope. 27.9% of the cats with HCM died over
the course of the study, but average survival for cats who developed
cardiovascular morbidity but who survived the first day after diagnosis
was 1.3 years. Since this was an average, some cats lived longer.. "A small
proportion of cats with hypertrophic cardiomyopathy had prolonged survival
reaching up to 15 years." Cats who never show symptoms often live
longer lives.
ACVIM factsheet: hypertrophic cardiomyopathy in cats
(2014) de Madron E American College of Veterinary Internal Medicine
says "cats with mild and focal hypertrophy without major blood circulation
disturbances may live a completely normal life."
Does this animal have congestive heart failure?
(2015) Luis Fuentes V Presentation to the World Small Animal
Veterinary Association states "many
cats with hypertrophic cardiomyopathy (HCM) will remain free of clinical
signs and will have a normal life expectancy."
Cats who have HCM associated with hyperthyroidism often recover once the
hyperthyroidism is under control.
Cardiac biomarkers in hyperthyroid cats
(2014)
Sangster JK, Panciera DL, Abbott JA, Zimmerman KC &
Lantis AC Journal of Veterinary Internal Medicine
28(2) pp465-472 discusses the difficulties of determining whether
heart changes in cats with hyperthyroidism are caused by heart disease or
by the hyperthyroidism. The study looked at the levels of NT-proBNP and
cTNI (cardiac troponin I) and found that levels of both were significantly
higher in cats with HCM or heart disease compared to healthy cats, but
levels reduced in cats with hyperthyroidism after the hyperthyroidism was
treated. The study concludes "overall, the findings supported previous
work in that thyrotoxic myocardial hypertrophy is largely reversible.
NT-proBNP might have a potential use in monitoring the response to
treatment of hyperthyroidism. If the plasma concentration of this
biomarker remains elevated three months after resolution of
hyperthyroidism, this could indicate underlying cardiomyopathy is also
present and an echocardiogram would be recommended."
Population and survival characteristics of cats with
hypertrophic cardiomyopathy: 260 cases (1990-1999)
(2002) Rush JE, Freeman LM, Fenollosa NK & Brown DJ Journal of
the American Veterinary Medical Association 220(2) pp202-207
found that "Median
survival time was 709 days (range, 2 to 4,418 days) for cats that survived
> 24 hours." This is quite an old study, and treatment protocols have
probably improved since then.
Plasma cardiac troponin I concentration and cardiac
death in cats with hypertrophic cardiomyopathy (2014) Borgeat
K, Sherwood K, Payne JR, Luis Fuentes V & Connolly DJ Journal of
Veterinary Internal Medicine28 pp1731-1737 looked at whether
levels of NTproBNP or
cardiac troponin (cTnl) might help with predicting cardiac death.
The study states "Median survival time (MST) to cardiac death was > 946
days. Cats with a cTnI > 0.7 ng/mL had a significantly MST of 40 days.
Those with NT proBNP >250 pmol/L also had a significantly shorter MST of
764 days."
Survival in cats with primary and secondary
cardiomyopathies (2016) Spalla I, Locatelli C, Riscazzi G,
Santagostino S, Cremaschi E & Brambilla P Journal of Feline Medicine
and Surgery18(6) pp501-509 states
that median survival time for cats with HCM was 865 days.
The prognosis is
worse if the cat develops
congestive heart failure
or arterial thromboembolism (blood clot in the legs).
Prognostic indicators in cats with hypertrophic cardiomyopathy
(2013) Payne JR, Borgeat K, Connolly DJ, Boswood
A, Dennis S, Wagner T, Menaut P, Maerz I, Evans D, Simons VE, Brodbelt DC
& Luis Fuentes V Journal of Veterinary Internal Medicine 27(6)
pp1427-36 examined the records of 282 cats diagnosed with HCM between 2004
and 2009. It states "Univariable predictors of an increased risk of
cardiac death included older age, absence of a murmur, presence of a
gallop sound or arrhythmia, presentation with either CHF or ATE, extreme
LV hypertrophy (≥ 9.0 mm), LV fractional shortening (FS%) ≤ 30%, regional
wall hypokinesis, increased left atrial size, decreased left atrial
function, spontaneous echo-contrast/thrombus or both, absence of left
ventricular outflow tract obstruction, and a restrictive diastolic filling
pattern."
I have not had good experiences with HCM myself (see
above), but I regularly
hear from people whose cats have lived for years with the condition.
Therefore I would always try treatment.
Congestive Heart Failure (CHF)
As
heart disease and/or kidney disease progress, congestive heart failure
(CHF) may develop.
Many
people panic when they hear this expression, fearing death is imminent.
Some cats with acute CHF are seriously ill and sadly will not make it,
however, this is not always the case. The word "failure" when used in a
medical context does not necessarily mean the end is nigh (just as CKD
used to be called chronic renal failure, but it was and is actually a
chronic condition), so try not to panic, because your cat's case may be
manageable.
What
happens in congestive heart failure is that the heart's ability to pump
blood around the body is impaired. This can adversely affect the kidneys,
since as part of that process blood flow through the kidneys is reduced.
The reduced ability to pump blood around the body can also lead to fluid
building up in the body (congestion), which needs to be removed.
Heart failure (2016) Kittleson MD
Merck Veterinary Manual has a detailed overview of heart failure.
Most cats
develop CHF because they have
HCM. Unfortunately it is possible for a cat
to have HCM with no symptoms until CHF appears, often acutely.
The risk of CHF
is higher if a cat has anaemia. It may also occur if a cat is overhydrated via too much fluid
therapy (both intravenously and
subcutaneously). Fluids are not a benign therapy and should only be given when
necessary and not in large quantities.
If your cat develops CHF within a week of starting
corticosteroids, the medication might be the cause.
Population and survival characteristics of cats with
hypertrophic cardiomyopathy: 260 cases (1990-1999)
(2002) Rush JE, Freeman LM, Fenollosa NK & Brown DJ Journal of
the American Veterinary Medical Association 220(2) pp202-207
states "Antecedent
events that may have precipitated CHF included i.v. fluid administration,
anesthesia, surgery, and recent corticosteroid administration."
Corticosteroid-associated congestive heart failure
in 12 cats (2004) Smith SA, Tobias
AH, Fine DM, Jacob KA & Ployngam T The International Journal of Applied
Research in Veterinary Medicine2 (3) pp159-170 found that some
cats developed a unique form of CHF within seven days of starting
steroids. Five of the cats died, but the seven that survived did much
better than the typical CHF patient once taken off the steroids.
Congestive Heart Failure Symptoms
The reduced
ability to pump blood around the body can lead to fluid building up in the
body (congestion). Signs of fluid
build up depend upon whether the body generally or the lungs in particular
are affected, but these are some of the symptoms you may see:
If you suspect
CHF for the first time, you should seek veterinary help as soon as possible.
If your cat has had CHF for some time, you will gradually learn which
signs in your particular cat require urgent veterinary help and which
require a less urgent vet visit or possibly can be managed at home.
Warning signs for congestive heart failure
Hayes J gives information on what
to watch for. Coco had both CKD
and heart problems, but she lived comfortably with CHF for quite some time.
Pulmonary Oedemaor Pleural Effusion
If
the problem lies on the
left side of the heart, fluid will accumulate:
in the lungs:
pulmonary oedema
around the
lungs: pleural effusion
Most cats have CHF because of HCM, which affects the left side of the
heart. Therefore it is more common to see pulmonary oedema or pleural
effusion in cats with CHF.
Pet Place has some information about
pleural effusion
If
the problem lies on the
right side of the heart, fluid will accumulate:
in the
abdomen (and occasionally the legs and paws): ascites
Other causes of ascites include cancer (my cat with cancer developed
ascites),
nephrotic syndrome, liver disease and
FIP (around 50% of cats with FIP will develop ascites).
Initially the vet will probably listen to your cat's heart with a
stethoscope (auscultation) and may hear crackling.
X-rays are generally considered to be the only
way to diagnose congestive heart failure. However,
Ohio
State University College of Veterinary Medicine were looking into the use of ultrasound
to diagnose heart failure, though results have not yet been published.
However, it must be borne in mind that troponin I may also be elevated in
cats with kidney disease even if they do not have "clinically relevant"
heart disease, according to
Cardiac troponin in cats with compromised renal
function (2019) Langhorn R, Jessen LR, Kloster AS, Jensen AP &
Koch J Journal of Feline Medicine and Surgery21(10)
pp985-991. The study does state that "it appears very likely that
secondary myocardial injury occurs in these cats."
If left
untreated, fluid build-up can kill so it is important to treat it. The
cat will often be treated in hospital initially, and then sent home for
ongoing care once stabilised. If your cat's case is mild, however,
hospitalisation may not be necessary.
Cardiovascular-renal axis disorders in the domestic
dog and cat; a veterinary consensus statement (2015) Pouchelon
JL, Atkins CE, Bussadori C, Oyama MA, Vaden SL, Bonagura JD, Chetboul V,
Cowgill LD, Elliot J, Francey T, Grauer GF, Luis Fuentes V, Sydney Moise
N, Polzin DJ, Van Dongen AM & Van Israël N Journal of Small Animal
Practice56(9) pp537–552 states "Unstable CvRDH,
such as in instances of acute CHF,
typically requires hospitalisation to restore or improve cardiac function
and to alleviate congestive or low output signs while simultaneously
evaluating risk of kidney dysfunction. Standard acute CHF therapy that
includes diuretics, ACEI, vasodilators and positive inotropes might need
to
be adjusted based on frequent assessment of hydration, renal function
biomarkers, electrolytes, blood pressure, body weight and urine output."
If medication is prescribed for home use, it is important to give it.
Association between survival time and changes in
NT-proBNP in cats treated for congestive heart failure (2017)
Pierce KV, Rush, JE, Freeman LM, Cunningham SM & Yang VK Journal of
Veterinary Internal Medicine31(3) pp678-684 found "Cats
whose owners did not have trouble administering medications had a longer
survival time compared to cats whose owners had trouble administering
medications."
Management of heart failure in cats
(2012) Luis Fuentes V Presentation to the 73rd SCIVAC International
Congress 2012 pp229-230 discusses the therapeutic goals and management
of feline heart failure
Mar Vista Vet has information on long
term therapy for heart failure.
The first step should be to remove the fluid that has built up.
If
your cat has pleural effusion (fluid build up around the lungs) or ascites
(fluid build up in the abdomen), needle aspiration may be offered and
offers immediate relief. It entails inserting a fine needle into the chest
(thoracocentesis or thoracentesis or chest tap) or abdomen (paracentesis)
and drawing the fluid off.
I know it sounds horrible,
but my cat had this done to remove ascites (caused by cancer in his case) and he didn't even flinch. However, it is a
delicate procedure, and skill is required to insert the needle in the
right place and remove the correct amount of fluid.
Pleural Port is an implanted port made by
Norfolk Pet Products to make it easier to access and remove the fluid.
Pleural Port accessing guide
mentions that some people can be taught to remove the fluid
themselves at home using the port.
Medications known as
diuretics may also be used to remove excess fluid build up. If your
cat is in crisis in hospital, these may be supplied in the injectable
form to remove the fluid quickly. In
many cases, diuretics will also be used on an ongoing basis to prevent fluid
building up again, usually in pill form.
For cats with
heart disease, diuretics are
often used in conjunction with other heart medications, especially
ACE inhibitors.
For
cats with CKD, it sometimes happens that the cat receives both sub-Q
fluids (usually in small amounts) and a diuretic. This sounds
counterintuitive but it seems to work for some cats, keeping them hydrated
while controlling their tendency to develop fluid build up.
Diuretics are also used occasionally when a cat in the end stages of CKD
has stopped urinating (anuria), in an attempt to "kickstart" the kidneys.
Furosemide
(Lasix)
The most
commonly used diuretic in cats is
furosemide (known as frusemide in the UK). Brand names include Lasix and Salix.
Drugs has some information about furosemide.
Furosemide is a
loop diuretic.
Diuretics (2016) Dowling PM Merck
Veterinary Manual states that "it
inhibits the reabsorption of sodium and chloride in the thick,
ascending loop of Henle, resulting in loss of sodium, chloride, and water
into the urine. Furosemide induces beneficial hemodynamic effects before
the onset of diuresis. Vasodilation increases renal blood flow, thereby
increasing renal perfusion and lessening fluid retention."
Furosemide is cleared through the kidneys so the kidneys have to work
harder to process the fluid that furosemide is removing.
Some people have found that another diuretic,
spironolactone, is easier
for their CKD cats to tolerate. However, furosemide is the best choice during times of crisis because it works
faster (spironolactone can take several days to work).
Furosemide
Formulations and Dosage
Hospitalised cats usually receive injectable furosemide.
Drugs says
of injectable furosemide "Furosemide is a potent diuretic which, if given
in excessive amounts, can lead to a profound diuresis with water and
electrolyte depletion. Therefore, careful medical supervision is required
and dose and dose schedule must be adjusted to the individual patient’s
needs."
The typical
dose for a cat receiving furosemide orally is 1 to 2 mg per kg (0.5 to 1 mg per pound) of cat.
It is usually given once or
twice daily, or occasionally less frequently, but
Pharmacokinetics of fursemide after intravenous,
oral and transdermal administration to cats (2019) Sleeper MM,
O'Donnell P, Fitzgerald C & Papich MG Journal of Feline Medicine and
Surgery21(10) pp882-886 found that oral furosemide is probably
best administered twice a day.
Cats with CKD may need
higher doses:
Diuretics (2016) Dowling PM Merck
Veterinary Manual states "Chronic therapy in cats and
some dogs can be accomplished by therapy every second or third day. Higher
than normal doses of furosemide
may be required in animals with renal disease due to functional
abnormalities of the renal tubule and binding of
furosemide to protein in the
urine."
In some cases,
furosemide resistance can occur.
Heart failure (2016) Kittleson MD
Merck Veterinary Manual states "Furosemide
resistance, typically defined by persistent signs of heart failure despite
dosages of 4 mg/kg, PO, tid, often develops in advanced cases of CHF.
Animals with resistance to chronic high doses of oral
furosemide may thus have an
improved diuretic response from parenteral (eg, SC) administration of the
drug or from addition of other diuretic agents (“diuretic stacking”)."
Furosemide
Side Effects and Interactions
Diuretics (2016) Dowling PM Merck
Veterinary Manual states "Furosemide
therapy is associated with a number of adverse effects. By nature of its
mechanism of action, it causes dehydration, volume depletion, hypokalemia
[low potassium levels], and hyponatremia [low sodium levels], which may be
excessive and detrimental."
Drugs warns
about using lactulose
(a constipation treatment) at the same time as furosemide, stating "Combining these
medications, especially over a prolonged period, may increase the risk of
dehydration and electrolyte abnormalities. In severe cases, dehydration
and electrolyte abnormalities can lead to irregular heart rhythm,
seizures, and kidney problems."
Spironolactone
Spironolactone is a diuretic which works by inhibiting aldosterone
activity.
Pet Place explains how
spironolactone works.
Spironolactone is not as commonly used as furosemide because it takes longer to work.
Diuretics (2016) Dowling PM Merck
Veterinary Manual states "The onset of action for
spironolactone is slow, and effects do not peak for 2–3 days.
Spironolactone is not recommended as monotherapy but can be added to
furosemide or thiazide therapy to treat cases of refractory heart
failure."
Spironolactone
Side Effects
Spironolactone is known as a potassium-sparing diuretic, because it does
not lower potassium levels in the cat's blood, as may happen with
furosemide.
Diuretics (2016) Dowling PM Merck
Veterinary Manual says "Because of the potential for
hyperkalemia, spironolactone
should not be administered concurrently with potassium supplements."
Drs Foster & Smith
give a list of possible side effects and signs of an allergic
reaction.
Using Diuretics and ACE Inhibitors or
ARBs Together
If you use diuretics at the same time as ACE inhibitors or ARBs, you
should check your cat's kidney values 7-10 days after starting the
treatment.
Mar Vista Vet says "monitoring kidney parameters is especially important
as both these medications serve to decrease blood supply to the kidney as
they support the heart. Should a heart failure crisis occur while a
patient is on these two medications, it will become necessary to rely on
the diuretic to resolve the crisis. High doses of diuretic are typically
needed. This can potentially lead to kidney failure though there is no
alternative when the heart is failing."
Pimobendan
Pimobendan (Vetmedin)
is a heart medication commonly used in dogs. It belongs to a family of
drugs known as inodilators. It helps the heart pump more efficiently by
opening up the blood vessels leading to and from the heart.
Researchers at Tufts University found that
pimobendan appeared to be helpful for cats who developed CHF following
intravenous fluids.
Use of pimobendan in 170 cats (2006-2010)
(2011) MacGregor JM, Rush JE, Laste NJ, Malakoff RL, Cunningham SM,
Aronow N, Hall DJ, Williams J, Price LL Journal of Veterinary
Cardiology13(4) pp251-60 found that pimobendan seemed to be
effective in cats with advanced heart disease and congestive heart failure
when used in conjunction with other heart medications.
Effect of oral administration of pimobendan on cats
with heart failure (2012) Gordon SG, Saunders AB, Roland RM,
Winter RL, Drourr L, Achen SE, Hariu CD, Fries RC, Boggess MM & Miller MW
Journal of the American Veterinary Medical Association241(1)
pp89-94 found that pimobendan worked well for certain types of heart
failure but that some cats with other types developed hypotension (low blood pressure). It
concluded "Additional studies are needed to establish dosages for
pimobendan and its effects before it can be recommended for treatment of
cats with CHF."
Case-control study of the effects of pimobendan on
survival time in cats with hypertrophic cardiomyopathy and congestive
heart failure (2014) Reina-Doreste Y, Stern JA, Keene BW, Tou
SP, Atkins CE, DeFrancesco TC, Ames MK, Hodge TE & Meurs KM Journal of
the American Veterinary Medical Association245(5) pp534-539,
looked at the effects of giving pimobendan to cats with CHF secondary to
HCM and HOCM. The study concludes "Cats
receiving pimobendan had a significant benefit in survival time. Median
survival time of case cats receiving pimobendan was 626 days, whereas
median survival time for control cats not receiving pimobendan was 103
days. No significant differences were detected for any other variable.
The addition of pimobendan to traditional treatment for CHF may provide a
substantial clinical benefit in survival time for HCM-affected cats with
CHF."
Nevertheless, there is some
debate about the use of pimobendan in cats with HCM.
Heart failure (2016) Kittleson MD Merck Veterinary Manual states
"There is ongoing debate regarding the use of pimobendan in cats.
Pimobendan is not approved for use in cats, and the package insert states
that it is contraindicated in cats with hypertrophic cardiomyopathy,
although several studies have suggested that the drug is safe in cats,
even those with hypertrophic cardiomyopathy, when administered at the same
dosage as in dogs. However, a pharmacokinetic study showed that the serum
concentration of pimobendan in cats given a canine dose results in a serum
pimobendan concentration 10 times that seen in dogs. Cardiac pathology is
found in dogs administered 3–5 times the recommended dose. It is unlikely
any species that experienced a similar calcium sensitization effect as
dogs could survive a dose 10 times the recommended dose, which suggests
that cats are somehow very different. This requires more investigation
before rational recommendations can be made with regard to using
pimobendan in cats. However, anecdotally and in one retrospective study,
pimobendan has been used in cats with CHF from any cause and has been
beneficial clinically. Consequently, if a cat is no longer responding to
conventional heart failure drug therapy, pimobendan (1.25 mg/kg/cat, bid)
may be tried."
In
2010, a member of Tanya's CKD Support Group whose cat had both CKD and HCM
was prescribed pimobendan by a vet school. Her cat did very well on it.
Pimobendan use in cats (2018) Focus on
Pharmacology Today's Veterinary Practice discusses when pimobendan
tends to be used in cats and possible side effects (which are rare).
Pimobendan Research
The University of California at Davis School of
Veterinary Medicine is currently
investigating the use of pimobendan to treat HCM generally, rather than
cats with congestive heart failure secondary to HCM.
Participants must have suspected
or confirmed HCM. Cats with heart murmurs, congestive heart failure or
elevated NT-ProBNP on bloodwork (>100pmol/L) are eligible but cats with
other systemic diseases (such as CKD, hypertension or on certain heart
medications are not. The trial only lasts one week, but cats may receive a
placebo rather than pimobendan. Contact
sterngenetics@ucdavis.edu for more information.
The
Tufts
studies found that Pimobendan not only helped with congestive heart failure, but the cats' kidney
values also improved. Research has since been conducted into its
effectiveness in treating CKD in cats. There is more information about
this here.
The Morris Animal Foundation is funding a
study at North Carolina State University which is looking into the
effectiveness of transdermal pimobendan in cats.
Bronchodilators:
Theophylline
Bronchodilators open up constricted airways in the
lungs. They are commonly used to treat asthma.
Occasionally they are used to treat CHF, and
Pet Care Rx
explains more about the use of theophylline in this way.
Theophylline is commonly used in the US and may also be
offered in the UK, though millophyline-V (etamiphylline) is also used in
the UK.
Mar Vista Vet says "Theophylline may
increase a patient's heart rate, exacerbating certain types of heart
arrhythmias or interfering with the heart's ability to fill. This could
especially be an issue with
hyperthyroid cats
or cats with
hypertrophic cardiomyopathy. Heart failure patients tend to clear
theophylline from their bodies more slowly than normal patients."
Plumb's Veterinary Drug Handbook (2011) says "The theophyllines should be
administered with caution in patients with severe cardiac disease, seizure
disorders, gastric ulcers, hyperthyroidism, renal or hepatic disease,
severe hypoxia, or severe hypertension."
I have not heard from anybody using a bronchodilator
for CHF for a long time (I used to hear from people using them when the
site first began, twenty years ago). I think better medications are available, but
be guided by your vet.
Congestive Heart
Failure Diet
The relationship between body weight, body
condition, and survival in cats with heart failure (2010) Finn
E, Freeman LM, Rush JE & Lee Y Journal of Veterinary Internal Medicine24(6) pp1369-1374 states "Cats
with the lowest and highest body weights had reduced survival times
compared with those with body weights in the intermediate ranges,
suggesting a U-shaped relationship between body weight and survival."
Cachexia and sarcopenia: emerging syndromes of
importance in dogs and cats (2012) Freeman LM Journal of
Veterinary Internal Medicine26 pp3-17 says "In cats with CHF,
cats with low body weights had shorter survival times compared with cats
with moderate or high body weights. These data emphasize the importance of
avoiding weight (and muscle) loss in dogs or cats with CHF by careful
attention to both the medical and nutritional aspects of their care.
Cardiac cachexia typically is recognized only after CHF has developed."
Feeding the aging heart
(2010) Freeman LM & Rush JE Presentation to the2010
Nestle Purina Companion Animal Nutrition Summit gives some advice on
food choices for cats with heart disease, including "Reduced protein diets
should be avoided in all animals with cardiac disease unless severe renal
dysfunction is present." They also say "L-carnitine supplementation may
have benefits even if a deficiency is not present by improving myocardial
energy production." Also the B vitamins, & "Omega-3 fatty acids appear to
be particularly useful in animals with anorexia or cachexia but also may
be beneficial in animals with less advanced cardiac disease (e.g., DCM,
CVD, HCM)."
Nutritional aspects of heart disease
(2012) Di Tollo BA Veterinary Focus22(1) pp11-16
states "Anorexia and the loss of water-soluble vitamins through the urine
when diuretics are administered both favor vitamin B complex deficiency.
Furthermore, cats with heart disease need more
B vitamins than healthy
cats. Diets for cats with heart disease should therefore contain levels of
water-soluble vitamins 2-3 times higher than that found in food for
healthy cats."
Feeding the cardiac patient Vermont
Veterinary Cardiology discusses feeding heart patients and has lists of
potentially suitable diets.
Oxygen
Cats with CHF
may need oxygen. Vets can provide this and you should always seek
veterinary assistance if your cat is having trouble breathing, but having an
oxygen tent at home may be helpful on
occasion, e.g. if you have just given your cat a diuretic and wish to keep
him/her comfortable while you wait for the medication to kick in.
Some members of
Tanya's CKD Support Group have bought the Buster ICU cage made by
Jorgensen Labs and have found
it helpful.
Unfortunately it seems to have been discontinued. Here is a link to the
medium size on
Amazon in case it comes back into stock.
It still seems to be in stock on
Amazon UK.
One
member of Tanya's CKD Support Group was able to rent an oxygen tent from a
local medical supply company with a prescription from her vet. It cost her
US$25 per month.
The effect of coenzyme Q10 on morbidity
and mortality in chronic heart failure. Results from the Q-SYMBIO study
(2013) SA Mortensen, A Kumar, P Dolliner, KJ Filipiak, D Pella, U
Alehagen, G Steurer, GP Littarru, F Rosenfeldt European Journal of
Heart Failure15 (S1), S20 found that in humans, "CoQ10
treatment was safe with a reduced all cause mortality rate. CoQ10 should
be considered as a part of the maintenance therapy of patients with
chronic HF."
CoQ10
may not be appropriate if your cat is on blood thinners such as aspirin or
clopidogrel.
PennState Hershey says "There have been reports that CoQ10 may make medications such as
warfarin (Coumadin) or clopidigrel (Plavix) less effective at thinning the
blood. If you take blood thinners, ask your provider before taking CoQ10."
If you do decide to try CoQ10 with your vet's
agreement, please do not stop using it suddenly. There have been several
cases of humans and one cat with heart disease
who were using CoQ10 relapsing after it was stopped suddenly.
It is important
to monitor cats with CHF in case the fluid build up returns. You should
watch for the symptoms discussed
above and should monitor your cat's
respiration rate and ideally heart rate.
Ask your vet to
teach you to listen to your cat's heart so you can monitor for any changes
that might indicate an approaching crisis. Ideally you
will know your cat's baseline measurements so you can tell when things are
getting out of kilter. If you did not know them before an episode of CHF,
measure them once your cat is stable again so you know what is typical
when there is no fluid build up.
I would also weigh your cat daily. If your cat's weight increases steadily
over the course of a few days, or if it increases abruptly, this may be a
sign of congestion.
Regular x-rays may also be helpful to avoid crises,
though you need to balance the need for these against the stress of vet
visits.
Sadly, some cats with acute CHF only have a short
period to live, but if you can find and treat the cause, your cat's
chances are much better. It is usually worth trying to control the
condition because, as with CKD, some cats do better than others,
especially if the CHF is caught before the cat is in crisis.
Population and survival characteristics of cats with
hypertrophic cardiomyopathy: 260 cases (1990-1999)
(2002) Rush JE, Freeman LM, Fenollosa NK & Brown DJ Journal of
the American Veterinary Medical Association 220(2) pp202-207
found that "Median
survival time was 709 days (range, 2 to 4,418 days) for cats that survived
> 24 hours." This is quite an old study, and treatment protocols have
probably improved since then.
Association between survival time and changes in
NT-proBNP in cats treated for congestive heart failure (2017)
Pierce KV, Rush, JE, Freeman LM, Cunningham SM & Yang VK Journal of
Veterinary Internal Medicine31(3) pp678-684 looked at levels
of NTproBNP in cats with CHF secondary to HCM. The median survival time
was 109 days, though five (out of 31) cats survived for 709 days or
longer (almost two years). The study states "Cats with a larger percent decrease in NT-proBNP
concentration from admission to discharge had a significantly longer
survival time compared to cats with a smaller percent change during
hospitalization. Cats that did not have signs of active CHF at the time of
the 7–10 day re-evaluation had a longer survival time compared to cats
with signs of active CHF at the re-evaluation." The study also notes that
NT-proBNP levels reduced a lot further in cats who were given
pimobendan, but the study did not conclude that pimobendan helps survival in CHF
cats, instead saying further research is needed.
Arterial Thromboembolism (ATE): Saddle
Thrombus or Blood Clot in the Legs
An arterial
thromboembolism is a blood clot which forms in the atrium (one of the
heart's chambers). The clot travels through the aorta (the main artery in
the body) until it reaches a place where it is too large to pass through
and it lodges there. This often occurs where the artery splits to go down
each leg, and an ATE which lodges here is called a saddle thrombus.
Depending upon exactly where it lodges, it may stop the blood supply to
one leg or to both legs.
PetCoach explains more about how
this happens (with diagrams).
Studies
indicate that 12-28% of cats with
hypertrophic
cardiomyopathy will develop ATE. Unfortunately, in
many cats the ATE is the first sign that the cat has heart disease.
Concurrent diseases and conditions in cats with
renal infarcts (2014) Hickey MC, Jandrey K, Farrell KS &
Carlson-Bremer D Journal of Veterinary Internal Medicine28(2)
pp319–323 found that cats with renal infarcts (death of kidney tissue
caused by a loss of blood supply) detected via ultrasound were more than
eight times more likely to experience an ATE than a cat without renal
infarcts.
An arterial
thromboembolism is life-threatening so you should consult a vet as soon as
possible.
Pet Place has a good overview of arterial
thromboembolism.
Your
vet will check your cat's legs, and may run blood tests.
Mar Vista Vet
says "The diagnosis is often clinched by comparing a blood glucose level
taken from the front of the body against one taken from the rear legs."
X-rays and an ultrasound may also be performed, especially if the cat has
not been previously diagnosed with heart problems.
Infrared thermography: a rapid and accurate
technique to detect feline aortic thromboembolism
(2018) Pouzot-Nevoret C, Barthélemy A, Goy-Thollot I, Boselli E,
Cambournac M, Guillaumin J, Bonnet-Garin JM & Allaouchiche B Journal of
Feline Medicine and Surgery 20(8) pp780-785used a special
camera to assess the temperature in all four limbs of cats admitted with
back leg paralysis and found there was a distint difference in temperature
between the front and back legs of cats with ATE, particularly in the left
legs. The study concludes "A minimal difference of 2.4°C
between ipsilateral affected and non-affected limbs has an excellent
specificity and high sensitivity for FATE diagnosis. Infrared thermography
seems to be a promising useful, easy, non-invasive and rapid method for
detecting aortic thromboembolism in cats, particularly in emergency
situations."
Arterial Thromboembolism Treatments
The mainstays
of treatment are pain management and heart medications. Your cat should be
hospitalised initially in order for these treatments to be provided.
If your vet
proposes a treatment plan, make sure it includes painkillers because this
is an extremely painful condition.
Arterial thromboembolism: risks, realities and a
rational first-line approach
(2012) Luis Fuentes V Journal of Feline
Medicine and Surgery14(7) pp459-470 says "Analgesia
is the main priority, and severe pain should be managed with methadone or
a fentanyl constant rate infusion."
Feline arterial thromboembolism a serious
consequence of cardiac disease...but not always a lost cause!
Kent A Newtown Veterinary Specialists says "Analgesia first! Stronger analgesics are recommended
initially, such as fentanyl, hydromorphone, morphine or buprenorphine.
Butorphanol should only be used if the pain is mild or if there are no
other options. Generally pain subsides after 24-48 hours and analgesia can
be tapered and eventually discontinued."
Bloodthinners: Clopidogrel (Plavix) and Aspirin
Current standard treatment methods commonly include antithrombotic treatment, i.e. medications are given to thin the cat's blood and reduce the risk
of more blood clots forming.
Arterial thromboembolism: risks, realities and a
rational first-line approach
(2012) Luis Fuentes V Journal of Feline Medicine and Surgery
14(7) pp459-470 says "Thrombolytic
therapy is not recommended, but antithrombotic treatment should be started
as soon as possible. Aspirin and clopidogrel are well tolerated."
Thrombolytic treatment (an attempt to dissolve the existing clot) is not
normally undertaken in cats. This is partly because this treatment needs
to be started within a few hours of the arterial thromboembolism (in
humans it must be started within six hours).
Thrombolysis with tissue plasminogen activator (TPA)
in feline acute aortic thromboembolism: a retrospective study of 16 cases
(2019) Guillaumin J, Gibson RM, Goy-Thollot I & Bonagura JD
Journal of Feline Medicine and Surgery21(4) pp340-346 found
that this type of treatment was no more effective than current standard
treatment methods. Having said that, 43.8% of the cats receiving
thrombolytic treatment survived to discharge versus only 28.9% of the cats
receiving standard treatment; but some of the cats receiving standard
treatment were not brought in for treatment as quickly, which may have
been a factor in their survival rate.
The
main blood thining medications used in cats are clopidogrel and aspirin.
Aspirin is
still used by some vets to thin the blood, though
clopidogrel is becoming more popular than aspirin for this purpose.
Plumb's Veterinary Drug Handbook says of aspirin "Likely a weaker, but less expensive
option than clopidogrel."
Sometimes cats with HCM are also offered low doses of aspirin, but if the
cat reacts badly, then aspirin is stopped.
Occasionally
aspirin is also used to help with
proteinuria.
One reason aspirin is becoming less widely used is
because it can be toxic to cats, who can only metabolise
it very slowly.
When it is used, aspirin is usually only given in very low doses once every three days.
Plumb's Veterinary Drug Handbook states that when used to treat arterial
thromboembolism, 5mg per cat can be given every three days, according to
one study, but that a later study suggests 81mg (one baby aspirin) every
72 hours, which is a much higher dose. To prevent thromboembolism, it
mentions a high dose of 40 mg per cat or
a low dose of 5 mg per cat, both orally every 72 hours.
Because cats are unable to metabolise aspirin well, you should be alert to
the signs of toxicity.
Pet MD
states "The progression of symptoms can occur quickly. One of the first
noticeable signs is loss of appetite. Other signs include vomiting,
diarrhea, and intestinal
hemorrhage brought on by ulceration in the stomach and small
intestines. The central nervous system may also be affected, causing your
cat to have trouble walking, appear weak and uncoordinated, or even
collapse. Loss of consciousness and sudden death can also occur. It also
mentions that "even nontoxic levels can produce these symptoms."
Plasma homocysteine, B vitamins, and amino acid
concentrations in cats with cardiomyopathy and arterial thromboembolism
(2000) McMichael MA, Freeman LM, Selhub J, Rozanski EA, Brown DJ,
Nadeau MR, Rush JE Journal of Veterinary Internal Medicine14(5)
pp507-12 found that cats with heart disease who have thrown a clot have
significantly lower levels of vitamin B6, vitamin B12 and
arginine, an
amino acid. The study concludes "We interpret the results of this study to
suggest that vitamin B12 and arginine may play a role in CM and ATE of
cats." You may therefore wish to discuss using
methylcobalamin (vitamin B12) with your vet.
Arterial Thromboembolism Prognosis
Sadly
the prognosis is poor, especially for cats with more than one leg
affected.
ACVIM consensus statement guidelines for the
classification, diagnosis, and management of cardiomyopathies in cats
(2020) Luis Fuentes V, Abbott J, Chetboul V, Côté E, Fox PR,
Häggström J, Kittleson MD, Schober K & Stern JA
Journal of Veterinary Internal MedicineEpub ahead of print
state "Most cats with ATE presented to first opinion practice are
euthanized. This approach is justifiable in terms of the cat's welfare and
generally poor prognosis, but if analgesia is adequate and favorable
prognostic factors are present (eg, normothermia, only 1 limb affected,
absence of CHF), an attempt at treatment can be considered provided the
owner is fully informed of the risks and overal prognosis."
Having said that, some cats do make a recovery, although another episode is possible.
Aortic thromboembolism associated with feline
hypertrophic cardiomyopathy (2002)
Rodriguez D & Harpster N Veterinary Practice Compendium24(6)
says "Although the prognosis is guarded, recovery from TE with
considerable disease-free intervals is possible with proper management."
Arterial thromboembolism in 250 cats in general
practice: 2004 - 2012 (2014)
Borgeat K, Wright J, Garrod O, Payne JR & Luis Fuentes V Journal of
Veterinary Internal Medicine28 pp102-108 examined the records
of cats with ATE treated by general practitioners in the UK. Over 61% of
the cats were euthanised immediately. More than 44% of the remaining cats
lived for at least seven days, even though not all the cats were given any
treatment. The study concludes "For cats that survived ≥ 7 days, median
survival time was 94 (95% CI, 42 – 164) days, with 6 cats alive 1 year
after presentation."
Who knows how
many more cats would have survived and for how long if they had been
offered treatment? These two studies report on cats with ATE from 5-27 years
ago, and treatments have improved since then. If your cat is given
clopidogrel, the chances of survival are probably higher, see
above.
I have heard from a small number of people whose cats lived for several years
after an arterial thromboembolism with no known recurrence. Not all of
these cats received clopidogrel. If you do decide to try treatment, make
very sure your cat receives painkillers!
Tissue
plasminogen activators are used in humans who have had strokes. TPAs are a
thrombolytic treatment, as opposed to an antithrombotic treatment, i.e.
an attempt is made to dissolve the blood clot.
Research is continuing into the use of treatments in cats.
Cats with blood clots
is a trial at Ohio State University College of Veterinary Medicine
into the use of TPAs for cats with ATE. Cats are eligible for the trial if
at least two limbs (but not all four) are affected, the event was observed
and TPA treatment (an infusion) can be begun within six hours of the ATE
occurring. Cats are ineligible if they are moribund or have unstable
congestive heart failure, have previously been given TPAs or cannot be
hospitalised for 48 hours. It should be noted that a cat participating in
the trial has a 50:50 chance of being given a placebo rather than a TPA.
The Morris Animal Foundation is funding
research at the University of Georgia into the use of an anti-clotting
drug called rivaroxaban for the prevention of blood clots in cats.
The study is aiming to see "if free
circulating DNA in cats contribute to saddle thrombus in cats with HCM.'
Bosentan
The efficacy of Bosentan, a mixed ETa ETb receptor
antagonist, in cats with arterial thromboembolism (2015)
Rozanski E & Buckley G Winn Feline Foundation (2015) reports on research into the use of a drug called Bosentan to
see if it helps cats with saddle thrombus. Ten cats with ATE were given
Bosentan while eight cats with ATE were not. Five of the cats given
Bosentan (50%) improved within 24 hours, whereas only two of the cats not
given Bosentan (25%) improved.
As far as I know, Bosentan is not currently widely
available.
Pacemakers
Cats tend not
to have the sort of heart problem which would benefit from a pacemaker (a
slow heart beat or arrhythmias),
but one member of Tanya's CKD Support Group received one in early 2017 and
is doing well on it.
Feline Heart Group
is a support group for people with cats with heart conditions including HCM.
This group has open archives, meaning
anybody can read what you write. However, this does enable you to read
about similar cases to your cat's without actually having to join the
group if you prefer.
TREATING YOUR CAT WITHOUT VETERINARY ADVICE CAN BE
EXTREMELY DANGEROUS.
I have
tried very hard to ensure that the information provided in this website is
accurate, but I am NOT a vet, just an ordinary person who has lived
through CKD with three cats. This website is for educational purposes
only, and is not intended to be used to diagnose or treat any cat. Before
trying any of the treatments described herein, you MUST consult a
qualified veterinarian and obtain professional advice on the correct
regimen for your cat and his or her particular requirements; and you
should only use any treatments described here with the full knowledge and
approval of your vet. No responsibility can be accepted.
If your cat
appears to be in pain or distress, do not waste time on the internet,
contact your vet immediately.
This site was
created using Microsoft software, and therefore it is best viewed in
Internet Explorer. I know it doesn't always display too well in other
browsers, but I'm not an IT expert so I'm afraid I don't know how to
change that. I would love it to display perfectly everywhere, but my focus
is on making the information available. When I get time, I'll try to
improve how it displays in other browsers.
This site is a labour of love. Please do not steal from me by taking credit for my work.
If you wish to
link to this site, please feel free to do so. Please make it clear that
this is a link and not your own work. I would appreciate being informed of
your link.