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Pet Health:
Heart Disease in Dogs and Cats

 

The heart consists of 4 chambers, all of which contain blood and are responsible for sending blood that is low in oxygen to the lungs to receive more oxygen, then sending this oxygen-rich blood throughout the body to all the tissues in need. 

A series of valves in the heart, separate the 4 chambers, and prevent blood from flowing where it shouldn't.  The heart muscle is a unique type of muscle, different from the other muscles in the body. 

In the dog and cat, disease is mainly seen as a problem with the valves of the heart, or in the heart muscle itself.  Click or scroll down for information on heart disease in cats or dogs:

Heart Disease in Cats

When heart disease occurs in the cat, it usually involves the heart muscle.  Unlike dogs, cats rarely develop disease only in their heart valves.  Symptoms of heart disease usually occur when the cat's heart begins to fail. 

Weakness, loss of appetite, weight loss, and difficulty breathing are common symptoms of heart failure in the cat.

Cardiomyopathy is the long name given to disease of the heart muscle.  It is usually divided into two categories:  thinning of the heart muscle (congestive cardiomyopathy), and thickening of the heart muscle (hypertrophic cardiomyopathy).  In both cases, the heart fails to "pump" blood adequately throughout the body.

Diagnosis is made by physical examination, X-rays, electrocardiogram, and ultrasound of the heart.  Most patients will have a heart murmur which can be heard by your veterinarian.
 
Treatment is geared towards increasing the amount of blood "pumped" by the heart per heart beat, decreasing fluid buildup in the lungs and chest, , and controlling any rhythm abnormalities.  Certain medications prescribed by your veterinarian are intended to help correct these conditions. 

Nutrient supplements added to the treatment plan, may also help correct the underlying heart problem.  Taurine is an essential amino acid, and has been found to be deficient in some cases of cardiomyopathy.  Replacement of taurine can be quite valuable in treatment of these cases.

 

Heart Disease in Dogs

When heart disease occurs in the dog, most commonly the valves of the heart become diseased .  Remember, the heart has 4 chambers, and is divided into right and left sides.  Each side has its own set of valves.  In certain breeds of dogs (Poodles, Cocker Spaniels, Yorkshire Terriers) there is a tendency towards developing problems with the heart valves (possibly inherited), although any breed can be affected.

The problem is with the valve itself.  It becomes blunted, or rounded in shape, and therefore fails to close properly.  When this occurs, blood tends to back-flow.  Back-flow of blood results in an overload of blood in the chamber receiving the back-flow.

Over time, this overload of blood can stretch out the receiving chamber causing it to enlarge.  Chamber enlargement may in time put pressure on local structures like the main airway in the lungs (the trachea or windpipe),  resulting in a dry, hacking cough.  Stretch of the chamber may also produce disturbances in the heart's rhythm resulting in an arrhythmia

Commonly, the overflow of blood can back up into the lungs, resulting in a "wet",  productive sounding cough. When this occurs, the patient is considered to be in "heart failure". Patients can become weak, stop or slow down on eating, sleep a good portion of the day, and cough.  Sometimes they will "faint" or collapse, showing signs of stiffness in the legs and arching back of the head. 

During these collapsing episodes, the patient may also loose control of the urine, stool, or both.  Clients often refer to these episodes as "seizures", which technically they are not.

Disease of the heart muscle is much less common than that of valve disease in the dog.  Heart muscle disease can be inherited as well, and is seen commonly in Cocker Spaniels, Boxers, Great Danes, and Doberman pincers.  Other breeds can also be affected. 

In this disease, the heart muscle "shrinks" or atrophies,  reducing the effective "pump" of each heart beat.  Weak heart muscles fail to pump blood adequately to the tissues of the body, and therefore can cause similar symptoms of weakness, decreased appetite, and cough, seen in heart valve disease.

Diagnosis of heart disease is made by physical examination, X-rays, electrocardiogram (ECG), and ultrasound of the heart.  Most patients will have a heart murmur which can be heard by your veterinarian. Specific tests can determine what form of heart disease exists, and then guide the veterinarian toward the appropriate treatment. 

Reducing the backflow of blood, reducing the size of the heart if enlarged, strengthening the heart beat itself, correcting abnormal heart rhythms, and clearing fluid back-up in the lungs are the goals of treatment.  Medications have been designed to accomplish these tasks either by themselves, or working along with other medications.

Your veterinarian will chose the drugs appropriate for your dog's situation.  In some instances of heart muscle disease, nutrient supplements may be added.  L-carnitine, and Taurine are two essential amino acids found deficient in some cases of heart muscle disease in the dog.  Addition of these essential amino acids in some cases may be very beneficial.