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Beaver Lake Animal Hospital
26325 SE 39th Street
Issaquah, WA 98029

Beaver Lake Animal Hospital

26325 SE 39th Street
Issaquah, WA 98029



Heart Disease in Cats

Heart Disease In Cats


General Information

            Heart disease in cats may be either congenital (present at birth) or acquired.  Congenital heart problems are varied, and depending on the severity, the problem may not become apparent for years.  Acquired disease also varies in type and severity.  Heart disease may be initially only detected based on auscultation (listening) of heart sounds upon regular examination.  Heart disease may be detected from the auscultation of a heart murmur (abnormal sound), rhythm abnormality, or other related physical abnormalities. Other times, the cat may be showing clinical signs of heart disease that leads to a veterinary exam.  Once heart disease is detected certain information obtained from diagnostic blood work, urinalysis, X-rays, ultrasound and blood pressure measurements will allow proper treatment to be started.  Depending upon initial presentation and other restrictions, basic treatment may be initiated to stabilize the patient.  In many cases, both heart and lung disease is present in the same pet.  Heart disease can lead to lung problems, and lung problems can lead to heart disease.  For instance, asthmatic cats may eventually develop cardiac failure.

            The heart in cats has two sides, just like in people.  The right side of the heart has blood that is delivered from the body, and is pumped to the lungs.  The left side of the heart has blood delivered from the lungs and is pumped to the body.  Each side of the heart has two chambers, the initial chamber, is a collection chamber, the second chamber pushes, or pumps the blood to its destination.  There are one-way valves that separate the two chambers on each side and another one-way valve that separates the second chamber from the vessels where the blood leaves the heart.  Blood is supposed to only go in one way, and out the other.  If a valve is not working of if the muscle is too flabby to close the valves, blood may start going back and forth from one chamber to the other.  Murmurs are the noise produced when blood flows abnormally, and/or a valve is not functioning properly.  Murmurs are graded by how easy they are to detect, from 1-6 with 6 being the worst/loudest.  In general, acquired murmurs get worse as the condition worsens.  There are characteristics of certain types of murmurs that give us an indication of what is causing the murmur/ heart disease.

            If the left side of the heart is not functioning properly, the blood (which has come from the lungs) backs up.  This increases the pressure of the blood in the lung vessels.  When this pressure is strong enough, fluid will leak out of the lung vessels and enter into the lung tissues and airways.  This is called pulmonary edema and is a life threatening condition.  However, it may start and be a mild condition for a long time.

            If the right side of the heart is not functioning properly, the blood (which has come from the body) backs up.  Much of this blood has come from the abdomen and liver.  This increases the blood pressure, including the pressure in the vessels coming from the liver.  This can eventually cause problems with the liver.  Excess fluid may be shed into the abdomen, a condition we call ascites.  Ascites is not desire able, and can cause other problems, but is not immediately life threatening except in severe cases.

Once heart disease is suspected, a thorough physical examination, laboratory tests for blood and urine, chest and abdominal radiographs (x-rays), blood pressure evaluation and electrocardiograms may be necessary to devise a proper treatment program and echocardiography (ultrasound) is recommended. However, if your pet is not showing clinical signs of heart disease, you may elect to wait on these services.  It is important to recognize, that heart disease is usually progressive and starting treatment may delay clinical signs of the condition.  If heart disease is suspected, your pet will need special evaluation prior to anesthesia.  Additionally, if heart disease is detected, good oral hygiene is important to help prevent further insult to the heart, lungs, liver and kidneys.


            The following are some types of heart disease in cats.


Hypertrophic Cardiomyopathy

            Hypertrophic cardiomyopathy is an abnormal thickening (hypertrophy) of the heart muscle of cats. The thickening causes improper filling and impaired pumping of the heart, as well as abnormal heart rhythm. These changes result in difficult breathing and fluid accumulation in the lungs. Lack of appetite and vomiting often occur 1 to 2 days before breathing difficulties appear. In some cases, blood clots develop and may cause paralysis of one or more legs or sudden death.

            The disease is most common in domestic shorthair cats, followed by domestic long hairs. Persian cats may be predisposed to the disease but Siamese, Abyssinians, and Burmese breeds are less frequently involved. Middle-aged male cats are most frequently affected.

Hypertrophic cardiomyopathy is a very serious disease. The prognosis (medical forecast) is guarded to good, depending on the response to treatment and development of abnormal heart rhythms or blood clots.



Dilative (Congestive) Cardiomyopathy

            In dilative cardiomyopathy, the heart muscle is severely weakened and the heart enlarges or dilates. This enlargement reduces the pumping efficiency of the heart and leads to heart failure. A dietary deficiency of the essential amino acid taurine is the most common cause of this disorder in cats. Other diseases, infections, or toxic substances that damage the heart muscle can also cause dilative cardiomyopathy.

            Dilative cardiomyopathy is primarily a disease of young to middle-aged cats (average is 7.5 years). Although all breeds of cats may be affected, the disorder is more common in Siamese, Abyssinian, and Burmese breeds.

            Dilative cardiomyopathy is a very serious condition, particularly during the early stages of treatment. Blood clots and shock are common complications and may be fatal. After 2 to 4 weeks, if the cat's condition is improving, the prognosis (medical forecast) is much better.



            Endocarditis is an inflammation of the lining of the heart and/or the valves of the heart. Usually it is caused by an infection in another part of the body, such as the teeth, tonsils, anal sacs, or kidneys. This infection reaches the heart through the bloodstream.

            Endocarditis is a serious disease and may cause death. Blood clots may develop and further complicate an already serious condition.

            Treatment for endocarditis is designed to eliminate infection. The severity of the condition and involvement of other parts of the body dictate whether hospitalization is necessary and the type of treatment used.  Extensive laboratory tests, including blood cultures, may be used to diagnose the condition and assess the response to treatment. Chest radiographs (x-rays) and other cardiac tests may be required.


Important Points of Treatment

1. Medication: Giving all medications on schedule is extremely important. Please call the doctor if you are unable to medicate your cat as instructed.

2. Activity: Your cat should be kept as quiet as possible. Do not allow your pet outdoors and do not encourage or stimulate your cat to chase any toys or other pets until well controlled.

3. Diet: A low-sodium (low-salt) diet is an important part of treatment. If possible, feed Prescription Diet h/d (available for purchase at your veterinary hospital).  Link to a homemade diet. 


Notify the Doctor if Any of the Following Occur

You cannot give the medicine as prescribed.

Your pet's condition worsens.

Your pet develops a limp.

Blood appears in your pet's urine or feces.

Your pet refuses to eat, is reluctant to move, or collapses.

Your pet develops a swollen abdomen or uncontrolled coughing.

Your pet seems to be in pain or cannot use its rear legs.

Your pet's general health appears to be deteriorating.