Heart Problems and CKD



Heart Murmurs

Arterial Thromboembolism (Blood Clot to the Legs)

Congestive Heart Failure (CHF)

Hypertrophic Cardiomyopathy (HCM)

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Home > Related Diseases > Heart Problems



  • Since the kidneys and heart are closely related, heart problems are relatively common in CKD cats.

  • This page covers the four main heart problems you may be faced with: heart murmurs, hypertrophic cardiomyopathy (HCM), arterial thromboembolism (saddle thrombus) and congestive heart failure (CHF).

  • Although it is a delicate balance, because the treatment for the heart condition may put additional strain on the kidneys and vice versa, it is often worth trying treatment.

  • Treating the heart must always take precedence.

Heart Problems and CKD                                                                                 Back to Page Index


If a cat has both a heart condition and CKD, the heart problem must always take precedence. 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 a try, because some cats do well.


How cats cope with heart disease varies from cat to cat, depending upon how advanced the disease 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. Try to keep stress to a minimum. 


Washington State University College of Veterinary Medicine has some suggestions on how to care for a heart patient at home.

Managing concurrent kidney and heart disease (2009) is an article by Jessica Tremayne in the October 2009 issue of Veterinary Practice News, which includes some information on diets for patients with both kidney and heart disease.

Feeding the aging heart (2010) Freeman LM & Rush JE Presentation to the 2010 Nestle Purina Companion Animal Nutrition Summit gives some advice on food choices for cats with heart disease.


Symptoms                                                                                                           Back to Page Index


Unfortunately many cats are asymptomatic or show very few symptoms, which is why it can be hard to diagnose heart disease. One of our cats, Harpsie, was suspected of having heart disease because of a high heart rate on two vet visits (which might just as easily have been caused by stress or "white coat syndrome") and weight loss. Other possible symptoms can be similar to those of CKD, including lack of appetite, lethargy and vomiting. You may also see faster breathing (the normal respiratory rate of a cat is around 20-30 respirations a minute).


In most cases, if you suspect heart problems, you can wait a day or two to see the vet. However, if you see the symptoms described under arterial thromboembolism or congestive heart failure, you should take your cat to the vet as soon as possible.


Diagnosis                                                                                                              Back to Page Index


Your vet may initially use a stethoscope to check your catís heart, and may follow this with a chest x-ray, especially if congestive heart failure is suspected. X-rays are the only way to diagnose pleural effusion, pulmonary oedema or ascites, all commonly seen in congestive heart failure.


The only way to obtain a definitive diagnosis of HCM is by way of echocardiogram (ultrasound), ideally with Doppler colour flow imaging. If heart problems are suspected, ideally you want to see a veterinary cardiologist to obtain an accurate diagnosis and a personalised treatment plan. Cavalier Health has details of veterinary cardiologists in the USA, Canada and the UK. 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.


Idexx Laboratories offers a new blood test which checks levels of a peptide called NTproBNP, which it states "can be clinically useful as an initial screening test for cats with suspected cardiac disease." However, Diagnosing feline heart disease (2010) Gordon SG NAVC Clinician's Brief mentions (see the box on page 2) 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 Practice 53(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."


One study, 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."


Therefore, whilst this test may be a useful starting point, I would not rely on it alone.


Laboratory tests for the diagnosis of heart disease and failure in dogs and cats (2007) is a presentation by A Boswood to the World Small Animal Veterinary Association World Congress 2007 which discusses the use of the NTproBNP test.

Cardiology: making the diagnosis (2001) is a presentation by Dr P Pion to the World Small Animal Veterinary Association World Congress explains more about how to diagnose heart problems.


Heart Murmurs                                                                                                   Back to Page Index


A heart murmur occurs when blood flows through the heart turbulently rather than smoothly. Heart murmurs are graded from 1 to 6 depending upon their severity: 1 is the lowest level at which a murmur can be heard by the vet, while 6 is the most severe and is an extremely loud murmur which is often audible without a stethoscope. 


A heart murmur is initially detected via a stethoscope, but if your vet wishes to investigate it further, additional tests can be performed, such as x-rays or ultrasound.


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.


Some cats have heart murmurs because they have a type of heart disease called hypertrophic cardiomyopathy, but it is also possible to have a heart murmur without having HCM - Prevalence of cardiomyopathy in apparently healthy cats (2009) Paige CF, Abbott JA, Elvinger F & Pyle RL Journal of the American Veterinary Medical Association 234(11) pp1398-1403 found that "in apparently healthy cats, detection of a heart murmur is not a reliable indicator of cardiomyopathy." Nevertheless, 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 & Surgery 13 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."


Merck Veterinary Manual has detailed information on heart murmurs.

Colorado State University lets you listen to feline heart sounds.

Pet Place has some information on heart murmurs (no need to register, just click Close at the bottom of the annoying pop up).

Veterinary Partner has information on heart murmurs and allows you to listen to a normal heart and to one with a murmur.

University of California at Los Angeles lets you listen to the different types of heart murmur - turn your speakers up loud for best effect. This is a human site but it should still give you an idea of what to listen for.


Arterial Thromboembolism (Saddle Thrombus or Blood Clot in the Legs)           Back

An arterial thromboembolism or saddle thrombus is a blood clot in the aorta which stops the blood supply to the legs. Symptoms include:

  • Limping or an inability to use the leg.

  • The affected leg is likely to be cold to the touch.

  • Often only one leg is affected, but in some cases a pair of legs (e.g. both rear legs) may be affected.

  • The affected leg is usually a rear leg, though I have heard of one cat who developed a blood clot in a front leg.

  • Weak legs (as opposed to limping) may also have other causes, see Index of Symptoms and Treatments

A saddle thrombus is life-threatening so you should consult a vet as soon as possible. If your vet proposes a treatment plan, make sure it includes painkillers because this is an extremely painful condition.


Heart medications such as Plavix (clopidogrel) and blood thinners are also commonly prescribed. The Winn Feline Foundation is funding research into the use of a drug called Bosentan to see if it helps cats with saddle thrombus.


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 Medicine 14(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.


Drs Foster & Smith explain more about thromboembolism, and provide a helpful diagram.

University of California at Davis has some information on blood clots in cats.

Manhattan Cats also has some detailed information on blood clots, including possible treatment options.

Pet Place has a good overview of saddle thrombus (no need to register to read it, just click the Close button at the bottom of the pop-up).

Systemic arterial embolism in cats (2007) is a presentation by Dr C Atkins to the World Small Animal Veterinary Association World Congress 2007 which discusses treatment and prevention.

Feline thromboembolism - new clinical perspectives (2007) is a presentation by Dr PR Fox to the World Small Animal Veterinary Association World Congress 2007 which discusses treatment options.

The American Association of Feline Practitioners reports on a trial led by Dr Dan Hogan of Purdue University College of Veterinary Medicine into the use of Plavix versus aspirin in cats who have previously thrown a clot. New applicants are welcome.


Congestive Heart Failure (CHF)                                                                       Back to Page Index


As heart disease and/or kidney disease progress, congestive heart failure (CHF) may develop. In CHF, the heart is really struggling to cope and fluid may accumulate:

  • in the lungs (pulmonary oedema)

  • around the lungs (pleural effusion)

  • in the abdomen (ascites) 

Signs of fluid build up, which are often a sign of congestive heart failure, include:

  • sudden weight gain

  • coughing

  • difficulty breathing

  • fast breathing (see Diagnosis for normal breathing rates)

  • open mouth breathing

  • loss of appetite (the fluid makes the cat feel full)

  • The cat may sit up and refuse to lie down; this is because it is easier to breathe in this position

  • A low body temperature may also be seen in congestive heart failure, so the cat may seek out warm places

If you suspect CHF, you should seek veterinary help as soon as possible. X-rays are the only way to diagnose congestive heart failure. If your cat has CHF, it is worth asking 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. Regular x-rays can also be helpful to avoid crises, though you need to balance the need for these against the stress of vet visits. See below for treatments.


Sadly, many cats with CHF only have a short period to live, but if you can find and treat the cause, your cat's chances are much better. The risk of CHF is higher if a cat has anaemia. It may also occur if a cat is overhydrated via too much sub-Q fluids. Sub-Qs are not a benign treatment and should only be given when necessary and not in large quantities. You can read more about what to watch for here.


If your cat develops CHF within a week of starting corticosteroids, this might possibly be the cause. One study, 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 Medicine 2 (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.


It is usually worth trying to control the condition because, as with CKD, some cats do better than others. If left untreated, fluid build-up can kill, so the fluid should be removed. For immediate relief, thoracocentesis (needle aspiration) may be performed: this entails inserting a fine needle into the chest and drawing the fluid off. It sounds horrible, but my cat had this done to remove ascites (fluid in the abdomen) 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.


Once the excess fluid has been removed, medications known as diuretics are commonly used to prevent the fluid building up too much in the future. These are often used in conjunction with other heart medications, especially ACE inhibitors. Research is currently underway to see if a medication called pimobendan might not only help cats with CHF but also help with CKD generally.


Effect of coenzyme Q10 therapy in patients with congestive heart failure: a long-term multicenter randomised study (1993) Morisco C, Trimarco B, Condorelli M Clinical Investigation 71 (8 Supp) pp134-6 demonstrated that in humans "the addition of coenzyme Q10 to conventional therapy significantly reduces hospitalization for worsening of heart failure and the incidence of serious complications in patients with chronic congestive heart failure". 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 Failure 15 (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." There is more information about CoQ10 here.


Pet Place explains more about thoracocentesis.

Pet Place has some information about pleural effusion (you don't need to register to read the article, just click on the Close This Window link at the bottom of the registration pop-up).

Macmillan Cancer Support explains more about pleural effusion.

Pet MD discusses pulmonary oedema in cats.

Pet MD has information about ascites.

My Optum Health explains more about ascites.

Warning signs for congestive heart failure is a helpful site by an individual whose cat, Coco, had both CKD and heart problems, and gives useful information on what to watch for. Coco lived with CHF for quite some time.

Emergency respiratory assessment (2001) Hughes D is a presentation to the World Small Animal Veterinary Association World Congress 2001. It is rather technical but may still be of use.


Vetgo discusses the usual treatments for congestive heart failure.

Mar Vista Vet has information on long term therapy for heart failure.


Hypertrophic Cardiomyopathy (HCM)                                                                  Back to Page Index


Cardiomyopathy means disease of the heart muscle, and in hypertrophic cardiomyopathy the left ventricle of the heart, which pumps blood through the aorta, the body's largest artery, is thickened. This thickening stops the heart expanding properly. 


HCM may be caused by an hyperthyroidism (an overactive thyroid) - in fact, Gulf Coast Veterinary Specialists claim that 87% of hyperthyroid cats will have some degree of HCM. Other possible causes include high blood pressure or CKD, while in some breeds, such as Maine Coons, Ragdolls or Sphynx cats, HCM is a genetic problem - The Winn Feline Foundation explains more about this. However, it is also possible for a cat to have HCM without any associated disease. 


HCM cannot be cured but it can be controlled by way of 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. It must be emphasised that it is essential to treat heart disease if it is present, and that treating the heart disease must take precedence over treating the CKD, which is an academic problem if the heart stops beating. 


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.


The International Cat Care in conjunction with the Veterinary Cardiovascular Society has set up an HCM screening scheme for UK cats.

Veterinary Partner has an overview of HCM.

Feline cardiomyopathy - establishing a diagnosis (2002) Fuentes VL, is a presentation to the 26th Annual Waltham/Ohio State University Symposium.

Feline cardiomyopathies - an update (2009) is a presentation by Anne French to the World Small Animal Veterinary Association World Congress which describes the various types of cardiomyopathy.


Commonly Used Heart Medications                                                               Back to Page Index


HCM is usually treated with drugs and it is fairly common to use more than one heart medication at a time. The different drug classes are:


Feline cardiomyopathies (2001) is a paper presented by Dr Paul Pion to the World Small Animal Veterinary Association World Congress in 2001, which gives typical heart drug dosages.


Some people also use an antioxidant called Coenzyme Q10 or CoQ10. There is more information about this here.


Beta Blockers

Beta blockers are used to slow a fast heart rate. Atenolol is commonly used in the USA. In the UK, a similar drug called Propranolol may be used.


Pet Place has an overview of atenolol. 

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.


ACE (Angiotensin-Converting-Enzyme) Inhibitors

These are drugs which prevent the conversion of a hormone called angiotensin I into another hormone called angiotensin II, the role of which is to constrict blood vessels. Therefore by using these drugs the blood vessels relax and this makes it easier for the heart to pump blood through the body. 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.  


ACE inhibitors are a popular treatment for heart disease, and a commonly used one is 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 frusemide (US: furosemide) (see below). 


Another ACE inhibitor, benazepril, is licensed under the trade name of Fortekor for the treatment of CKD in cats in the UK, Europe and Australia, even for cats without heart disease. Further information about this can be found in the Treatments section. 


An ACE inhibitor called Ramipril (marketed as Altace or Vasotop) is available in the UK and Europe, though I only know of a couple of people who have used it for their cat. The efficacy, tolerance and safety of the angiotensin converting enzyme inhibitor ramipril in cats with cardiomyopathy with or without hypertension (2002) Schille F & Skrodski M is a paper presented to the World Small Animal Veterinary Association World  Congress 2002.


It is not unusual for cats suffering from congestive heart failure to be given both an ACE inhibitor and a diuretic.


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. The most commonly available one is called Diltiazem. Another member of the calcium channel blocker family, amlodipine, is the best choice for controlling hypertension in cats.



Bronchodilators are used in asthma, but may occasionally be used to treat heart problems - they open up constricted airways in the lungs. Millophyline-V (etamiphylline) is commonly used in the UK; theophylline is commonly used in the US and may also be offered in the UK. 


Veterinary Partner has information on the use of theophylline.



Diuretics may be used for congestive heart failure in order to rid the body of excess fluid. They are also used occasionally when a cat in the end stages of CKD has stopped urinating (anuria), in an attempt to "kickstart" the kidneys. The most common diuretic used in the UK is a drug called frusemide (furosemide in USA), which is commonly sold under the name of Lasix, although the name is currently being changed to Salix.  Lasix is very hard on the kidneys, but some people have found that another diuretic, spironolactone, is gentler. However, Lasix is the best choice during times of crisis.


It is not unusual for cats suffering from congestive heart failure to be given both an ACE inhibitor and a diuretic.


Lactulose may exacerbate the effects of diuretics. Drugs has more information about this.


Mar Vista Vet has more information on Lasix (frusemide or furosemide), including cautions about using diuretics at the same time as ACE inhibitors.

Pet Place has more information about spironolactone.



Aspirin may be used in an attempt to reduce the chances of blood clots forming. Occasionally it is also used to help with proteinuria.


Aspirin can be toxic to cats, who can only metabolise it very slowly, and should only be given to a cat on veterinary advice; it is usually only given in very low doses once every three days. In the USA, cats with HCM are routinely given carefully assessed doses of aspirin in addition to other medications, but if the cat reacts badly, then aspirin is stopped.


Mar Vista Vet has information on aspirin.

Pet MD has some information about aspirin poisoning in cats.



This is a heart medication which is commonly used in dogs and which is now being assessed in cats, particularly for the treatment of congestive heart failure. Research is also underway into its effectiveness in treating CKD in cats. There is more information about it here.

Links                                                                                                                         Back to Page Index


Veterinary Links

Long Beach Animal Hospital - explains how the heart works, and the Specific Diseases link discusses HCM.

Vetinfo an overview of feline heart problems and medication by a US vet.

Vetinfo - this is a reply by the same vet to a query about the use of the usual heart medications in cats with CKD, particularly ACE inhibitors such as enalapril (Enacard) or benazepril (Fortekor).

The heart-kidney axis with a special focus on renal function in heart failure (2007) Lefebvre HP  State of the Art in Renal Disease in Dogs and Cats Proceedings, Vetoquinol Academia, reports on how heart and kidney problems interact (go to page 44).

Cardiorespiratory diseases of the dog and cat is the online version of a detailed book by a veterinary cardiologist.


Other Links

International Cat Care - an overview of HCM by the UK feline charity.

Boo Boo's Story - this is a site about Boo Boo, a cat who was treated for both CKD and HCM using holistic methods.

Ragdolls - Ragdolls (and Maine Coons) can be prone to HCM, and this site has good  pictures of a healthy heart and an HCM-affected heart.

Jody Chinitz's site - this site is by a lady who lost a cat to HCM.

Feline Heart Group - a support group for people with cats with heart conditions, where you can obtain feedback on treatments, and support on living with HCM and other feline heart problems. (Note: this group has open archives, meaning anybody can read what you write).


Back to Page Index

This page last updated: 22 September 2013

Links on this page last checked: 02 April 2012