Congestive Heart Failure (CHF)

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. 

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."

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.

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 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 or Ragdolls, 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 can often be managed with heart medications.

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.

Congestive Heart Failure (CHF)                                                                            Back to Page Index

As heart disease and/or renal disease progress, congestive heart failure 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) 

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 you suspect CHF, you should seek veterinary help as soon as possible. See below for possible symptoms.

Sadly, many cats with CHF only have a short period to live, although it is usually worth trying to control the condition because, as with CKD, some cats do better than others. Treatment commonly includes the use of diuretics.

Macmillan Cancer Support explains more about pleural effusion.

Pet MD discusses pulmonary oedema in cats.

Health A to Z 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.

Diagnosis                                                                                                                 Back to Page Index

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.

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

X-rays are the only way to diagnose pleural effusion, pulmonary oedema or ascites, all commonly seen in congestive heart failure.

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, 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. The only way to obtain a definitive diagnosis of HCM is by way of echocardiogram (ultrasound), ideally with Doppler colour flow imaging. 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.

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.

The Feline Advisory Bureau in conjunction with the Veterinary Cardiovascular Society has set up an HCM screening scheme for UK cats.

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

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).

More Serious Symptoms

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

Saddle Thrombus (Blood Clot in the Legs)

A 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 cats who developed saddle thrombus 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.

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.

Fluid Build-Up/Congestive Heart Failure

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

• sudden weight gain

• coughing

• difficulty breathing

• fast breathing

• 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 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.

Treatments                                                                                                                Back to Page Index

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.

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

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.

Congestive Heart Failure Treatments

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 or abdomen 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 duretics 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.

Vetgo discusses the usual treatments for congestive heart failure.

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

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 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".

HCM Treatments

HCM cannot be cured but it can be controlled by way of drugs. 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.

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

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.  

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

Aspirin

Aspirin may be used in an attempt to reduce the chances of blood clots forming. 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.

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This page last updated: 15 October 2011