Many cats will need anaesthesia at some point
in their lives.
Anaesthesia always carries a small risk, and
this risk can be higher in a CKD cat.
This page explains more about the precautions
you can take to minimise the risks.
Introduction
Sometimes a CKD cat needs to have a general anaesthetic. The most
usual reason in a CKD cat is dental surgery, but cats sometimes need anaesthesia for other reasons, perhaps to have a growth removed or to have
kidney stones treated.
I know you don't want your cat to undergo general anaesthesia. The mere
thought of it terrifies me, and I'm a gibbering wreck whenever one of my
cats needs it. There are always risks associated with anaesthesia, but if
your cat is in pain (and believe me, dental pain is horrible), or if s/he won't survive much longer without surgery,
then you will have to decide whether to go ahead.
The risks of anaesthesia are varied, but breathing and heart
rate may be affected, and aspiration may occur if the airway is not protected.
Low blood pressure (hypotension) can be caused by anaesthesia.
AAFP feline anesthesia guidelines
(2018) Robertson SA, Gogolski SM,
Pascoe P, Shafford HL, Sager J & Griffenhagen GM Journal of Feline
Medicine and Surgery 20(7) pp602-634 say "hypotension
is a common anesthetic complication, even in healthy cats undergoing short
procedures."
Hypotension is a particular concern for CKD cats because it may
damage the kidneys and therefore increase the risk of CKD developing or
worsening.
Risk factors associated with the development of
chronic kidney disease in cats evaluated at primary care veterinary
hospitals (2014) Greene JP, Lefebvre SL, Wang M,
Yang M, Lund EM & Polzin DJ Journal of the American Veterinary Medical Association244 pp320–327 found that "Risk
factors for CKD in cats included ... prior periodontal disease
or cystitis, anesthesia or documented dehydration in the preceding year."
What is considered hypotension?
AAHA Anesthesia and Monitoring Guidelines for Dogs
and Cats (2020) Grubb T, Sager J, Gaynor JS, Montgomery E, Parker
JA, Shafford H & Tearney C Journal of the American Animal Hospital
Association56(2) pp59-82 say "hypotension is a common complication during anesthesia and is defined as
BP values of systolic ,80–90 mm Hg, mean ,60–70 mm Hg, and diastolic ,40
mm Hg."
Fortunately, many of
the risks can be managed, which reduces the chances of problems developing.
The risk of death: the confidential enquiry into
perioperative small animal fatalities (2008) Brodbelt DC, Blissitt KJ, Hammond RA, Neath PJ, Young LE,
Pfeiffer DU & Wood JL Veterinary Anaesthesia & Analgesia35(5)
pp365-73 reports on the anaesthesia of 79,178 cats and found the risk of
death was 0.24%, rising to 1.4% in sick cats. The study states that
"Greater patient care in the postoperative period could reduce
fatalities."
Preparing for Surgery
According to
AAHA Anesthesia and Monitoring Guidelines for Dogs
and Cats (2020) Grubb T, Sager J, Gaynor JS, Montgomery E, Parker
JA, Shafford H & Tearney C Journal of the American Animal Hospital
Association56(2) pp59-82,
"“anesthesia” is not limited to the period when the patient is unconscious
but is a continuum of care that begins before the patient leaves home and
ends when the patient is returned home with appropriate physiologic
function and absent or minimal pain levels."
The first thing to do is to find a vet you trust to perform the surgery.
As Robert Smith MD put it, "There
are no safe anesthetic agents, there are no safe anesthetic procedures.
There are only safe anesthetists."
(Smith’s Anesthesia for Infants and
Children (1959)
Mosby).
You also need to decide whether to use a specialist. Most vets can perform
a variety of surgical procedures, but for certain types of surgery, such as
kidney
stone treatment such as SUBs or stents, you will need a specialist. You may
also wish to use a dental specialist if your cat is undergoing dental
surgery (see
Dental
Problems for more information).
You should always have a physical exam and bloodwork
performed and blood
pressure checked before surgery, so any problems can be addressed. If your
cat has heart issues,
you may also wish to see a veterinary cardiologist prior to surgery.
If your cat is on blood pressure medication such
as amlodipine (Norvasc) or benazepril (Fortekor), ask your vet if you
need to stop the medication before the surgery (since anaesthetics may reduce
blood
pressure).
AAHA Anesthesia and Monitoring Guidelines for
Dogs and Cats (2020) Grubb T, Sager J, Gaynor JS, Montgomery E, Parker
JA, Shafford H & Tearney C Journal of the American Animal Hospital
Association56(2) pp59-82 advises stopping benazepril and
has a list of which medications can normally be given and which not.
It is very important to fast your cat before
anaesthesia. This will usually be done for several hours before
surgery, often overnight, but a shorter period may be possible in some
cases, so be guided by your vet. Your cat may be allowed to drink
water until a couple of hours before surgery, which can be helpful for
a CKD cat, but your vet will decide what is the best approach for your
cat.
All cats should be placed on
intravenous (IV) fluids during and after
any
procedures. This is to avoid falls in blood pressure during the
procedure, which may damage the kidneys (see
above).
CKD cats
should also be placed on intravenous fluids for a few hours before any surgery.
Not every vet wishes to place a CKD cat on IV
fluids before anaesthesia, but this is very important for your cat's
safety. In
Chronic kidney disease
(2007) Polzin DJ
Delaware Valley Academy of Veterinary Medicine,
Dr Polzin (a kidney specialist) states "It appears that the medical
prophylaxis most likely to be effective is related to pre-intervention
fluid support. Pre-loading patients with fluids before potential ischemic
or nephrotoxic interventions has thus far been shown to be the most
effective therapy. Other options that have been investigated include
diuretics, vasodilators, and some forms of metabolic support. However,
none have thus far proven to be superior to support with a saline-based
fluid. Usually, fluids should be administered in sufficient volume to
induce diuresis."
AAFP feline anesthesia guidelines
(2018) Robertson SA, Gogolski SM,
Pascoe P, Shafford HL, Sager J & Griffenhagen GM Journal of Feline
Medicine and Surgery 20(7) pp602-634 are quite technical but
have a section about anaesthesia in CKD cats which states "Preanesthetic
fluid therapy may be of value to restore normovolemia and hydration."
2013 AAHA/AAFP fluid therapy guidelines for dogs and
cats (2013) Davis H, Jensen
T, Johnson A, Knowles P, Meyer R, Rucinsky R & Shafford H Journal of
the American Animal Hospital Association49(3) pp149-159 state
"patients with uremia benefit
from preanesthetic fluid
administration."
Depending upon the type of surgery involved, antibiotics may need to be given to the cat for several days in
advance, and continued for 5-7 days afterwards.
All cats should be placed on IV fluids during and after
any
procedures. This is to avoid reduced blood flow and falls in blood pressure during the
procedure, which may damage the kidneys.
Perioperative anaesthetic care of the cat undergoing
dental and oral procedures: key considerations
(2015) De Vries M & Putter G Journal of Feline Medicine and
Surgery17 pp23-36 states "It is recommended that IV fluids are
provided during anaesthesia, not only to compensate for ongoing losses and
potential haemorrhage but also to counteract any relative hypovolaemia
resulting from anaesthetic agent-induced hypotension."
This is even more important for CKD cats.
Anesthesia for patients with renal disease
(2015) Rezende M & Mama K Clinician's BriefMar 2015 pp41-44
states "The kidneys are
particularly susceptible to ischemic injury because the distribution of
blood flow within the kidneys is not uniform or proportional to demand;
despite its higher metabolic rate, for example, the renal medulla only
gets 15% of the overall renal blood flow (RBF). Therefore, a decrease in
cardiac output and blood pressure— as may be observed with anesthetic drug
administration—has the potential to further compromise renal function."
They go on to say "vascular volume and blood pressure support
remain the most important aspects of protecting renal function during
anesthesia management."
Any drugs used on a CKD cat during anaesthesia which are cleared by the kidneys may
require a reduction in the dose, since damaged CKD kidneys may not clear
them as fast as healthy kidneys.
Anesthetic hypotension (2017) Jimenez
Lozano MA Clinician's BriefMar 2017 pp27-30 discusses steps
your vet can take should your cat's blood pressure fall too low during the
procedure.
Anaesthetic Choices
The main concern during the surgery is
often the anaesthetic.
You should discuss with your vet the type of anaesthesia that will be used
on your cat. Generally speaking, animals undergoing surgery receive two
types of anaesthesia:
an induction agent to induce unconsciousness; and
general anaesthesia to keep them unconscious whilst the procedure is being
performed.
discusses the use of anaesthesia in older cats, including cats with
kidney disease.
Renal disease management basics (2004)
Stein B Veterinary Anesthesia and Analgesia Support Group
recommends a particular anaesthesia protocol for patients with
kidney disease. Ask your vet to
follow this, or to explain any changes to you.
Induction agents used in cats are usually in the form of injections. A
commonly used induction agent is
propofol.
Veterinary Anaesthesia and Analgesia Support Group
mentions that "alfaxalone has little or
no cardiovascular effects when given in the normal dose." This might make
it a better choice for a cat with heart disease.
Ketamine is not recommended
because it has to be cleared by the kidneys.
Some vets do not use an injectable induction agent, but instead use
an
inhaled anaesthetic both to induce unconsciousness and to provide general
anaesthesia. Using inhaled anaesthetics in this way is sometimes referred
to as "masking down." I would ask your vet not to do this,
because injected
induction agents are safer.
Serenity now: practical sedation options for cats
(2015) Shafford HL, a veterinary anaesthetist, says "Box inductions
should be avoided because they are 1) scary and stressful for patients, 2)
dangerous to personnel (exposure to inhalants associated with numerous
adverse health effects including impaired reproductive function), and 3)
dangerous to the patient (exposure to high levels of potent
cardiorespiratory depressant, inability to monitor and support
cardiovascular or respiratory system during induction, increased
mortality)."
General Anaesthetics
General anaesthetics take various forms. Although
inhaled anaesthetics are not the best choice for induction purposes,
as general anaesthetics they can be a good choice for CKD cats. These are gases, which put
less strain on the cat's body than other types of anaesthetic, and they
also enable the vet to stop the procedure and bring your cat round
immediately if there are any problems during surgery.
One commonly used inhaled anaesthetic is isoflurane.
Some vets prefer another inhaled anaesthetic called sevoflurane, but
Anesthesia for patients with renal disease
(2015) Rezende M & Mama K Clinician's BriefMar 2015 pp41-44
states "Because of the known nephrotoxic
metabolites (eg, compound A) produced by sevoflurane, it is best to avoid
this drug even though any toxic effect may be minimal in a stable patient
with renal disease. Therefore, the use of isoflurane is generally
recommended."
If your cat is to receive an inhaled anaesthetic
following induction with an injectable induction agent, usually an
endotracheal tube is inserted into the cat's throat to administer the
inhaled anaesthetic and to help the cat to breathe.
The main downside of inhaled anaesthetics is that they may cause low blood
pressure, which can damage the kidneys. It is therefore essential that
your cat's blood pressure is monitored during the procedure and that
intravenous fluids
are given before, during and after the procedure.
After
Surgery
Your cat should be monitored closely after surgery.
AAFP feline anesthesia guidelines
(2018) Robertson SA, Gogolski SM,
Pascoe P, Shafford HL, Sager J & Griffenhagen GM Journal of Feline
Medicine and Surgery 20(7) pp602-634 state that
"Sixty percent of all anesthetic-related cat deaths occur during the
recovery period, especially the first 3 h."
Some cats develop a low temperature during or following
anaesthesia.
Perioperative anaesthetic care of the cat undergoing
dental and oral procedures: key considerations
(2015) De Vries M & Putter G Journal of Feline Medicine and
Surgery17 pp23-36 states "Cats
are prone to hypothermia due to their high body surface area to volume
ratio. Unfortunately, the importance of body temperature monitoring and
support is largely still underestimated in veterinary medicine." Also
see above for the
optimal temperature in the operating room.
Therefore you should ensure that your cat's temperature is closely monitored
after surgery. Some vets warm the fluids given to the cat but
Heated intravenous fluids alone fail to prevent
hypothermia in cats under general anaesthesia
(2017) Jourdan G, Didier C, Chotard E, Jacques S & Verwaerde P
Journal of Feline Medicine and Surgery19(12) pp1249-1243 found
that "heated fluid alone fails to prevent intraoperative hypothermia in
cats." It speculates that this might have been the case in this study because of the low infusion rate
of 5 ml per kg of cat per hour.
Your cat might benefit from a heat pad immediately
following surgery.
The American Association of Feline Practitioners
Senior Care Guidelines
(2009) Pittari J, Rodan I, Beekman G, Gunn-Moore D, Polzin D, Taboada J,
Tuzio H & Zoran D Journal of Feline Medicine & Surgery11
pp763-778 states "Since hypothermia is
common, evaluate body temperature every 15 mins, continuing
postoperatively until the cat is ambulatory or normothermic. Support body
temperature by using tools such as a heated cage, hot air blankets,
water-circulating heating pad, and/or booties." If your vet
uses a
heat pad,
this should only be used once the cat is able to move off the pad
of his/her own volition should they start to feel too hot.
Your cat should also receive intravenous fluids
during the recovery period.
The Winn Feline Foundation
(2020) is funding research into the
effects of general anaesthesia on kidney function in cats and whether
intravenous fluids may reduce these effects, but in the meantime
2013 AAHA/AAFP fluid therapy guidelines for dogs and
cats (2013) Davis H, Jensen
T, Johnson A, Knowles P, Meyer R, Rucinsky R & Shafford H Journal of
the American Animal Hospital Association49(3) pp149-159 state
"Patients that may benefit from fluid
therapy after anesthesia include geriatric patients and patients with either renal disease or ongoing fluid
losses from gastrointestinal disease."
Anaesthesia for the geriatric dog and cat
(2008) Hughes JML Irish Veterinary Journal61(6)
pp380–387
also states "All recovering geriatric patients should receive oxygen
supplementation and be monitored closely until their protective
pharyngeal reflexes have returned."
Blood pressure should also be monitored for a week or so afterwards
because although low blood pressure is a risk during surgery, surgery and anaesthesia may cause increases in blood pressure
following the procedure.
If inhaled anaesthesia has been used, your cat will have a tube down the
throat during surgery (intubation), which can cause the throat to feel a
little sore for a day or two afterwards.
After most types of surgery
painkillers
are necessary.
WSAVA guidelines for recognition, assessment and
treatment of pain (2014) Mathews K, Kronen PW, Lascelles D,
Nolan A, Robertson S, Steagall PVM, Wright B & Yamashita K Journal of
Small Animal Practice55(6) ppE10–E68 points out that "pain
associated with surgery is 100% predictable."
Your cat may be able to come home a few hours after surgery, or may have
to stay in the hospital overnight or for a day or so. If you bring him or
her home soon after surgery, keep him/her in a warm, quiet place. Your cat
may be a little wobbly at first, but this should soon improve. If you have
any concerns, contact your vet.
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.
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