Hours of Operations
We are available to see your pets for all of their cardiology needs Monday – Friday, 8 a. m. – 6 p.m. We also offer drop off appointments for your convenience for recheck appointments on a case-by-case basis, which can be scheduled Monday, Tuesday, Wednesday or Friday. Pets can be dropped off as early at 7:15 a.m. and picked up as late at 6:30 p.m. Please contact our office at 713.693.1155 for further details, or to schedule an appointment.
- Monday – Friday, 8 a. m. – 6 p.m.
Client Service Information
Dilated cardiomyopathy (DCM) is one of the most common acquired heart diseases that we see. Large and giant breed dogs are most often affected but it has been diagnosed in smaller breed dog and in cats as well.
What exactly is Dilated Cardiomyopathy?
DCM defines a condition where the heart muscle (myocardium) becomes very thin and is unable to contract normally. Since the myocardium cannot work effectively to pump blood out of the heart, the heart becomes enlarged. Subsequent back up of blood into the left atrium and ultimately into the lungs is a common occurrence. This back up of blood into the lungs results in bruising (pulmonary edema) and is a sign of congestive heart failure.
What causes DCM?
While there have been many theories as to the cause of DCM, the exact mechanism is still not entirely understood. It is believed that the majority of cases have a familial or genetic component. One reason for this theory is the preponderance of the disease in specific breeds such as the Doberman Pinscher, Great Dane or Boxer. Although specific genetic evidence is still lacking, the disease has been linked to an abnormal gene found in Portuguese Water Dogs.
There is a small population of dogs in which DCM may have a nutritional component. Taurine is an amino acid required for the development and function of normal muscles, including the heart muscle. Pets that develop DCM on taurine deficient diets such as vegetarian diets, may benefit from supplementation. It is important to note that not all cases that are supplemented with taurine will improve.
L-carnitine is another amino acid that has been implicated in the development of DCM in people. However, there is little evidence in dogs to suggest that supplementation with carnitine reverses cardiac dysfunction.
It is difficult to firmly establish a link between taurine or carnitine deficiency and heart disease because measurement of these compounds in the blood is not an accurate reflection of their levels in the myocardium.
What are the signs of DCM?
The signs of DCM can vary widely and may depend on the breed of dog. Coughing, labored breathing, episodic weakness or fainting are signs often seen in Dobermans. Unfortunately sudden death may also occur in patients with this problem. Respiratory signs are seen due to pulmonary edema and/or heart enlargement. Other large breed dogs may have fluid accumulation in the abdomen (ascites) or in the chest cavity (pleural effusion). Other signs may include loss of appetite, pale gums, elevated heart rate or lethargy.
How is DCM diagnosed?
Often, a thorough physical exam coupled with the signs and information about the breed, are sufficient to make a presumptive diagnosis of DCM. Some tests that help support the diagnosis are an ECG (electrocardiogram) and x-rays of the chest. The ECG often indicates an arrhythmia (abnormal heart rhythm) and an elevated heart rate. The chest x-rays will verify an enlarged heart and show evidence of congestion in the lung tissue (pulmonary edema).
There is a certain subset of dogs that can have abnormal heart rhythms without having enlarged hearts. These dogs may still be classified as early DCM.
A definitive diagnosis of DCM is made by performing an ultrasound of the heart (echocardiogram). An echocardiogram allows us to visualize the interior of the heart and assess its function. Measurements of the wall thickness and pumping capability of the heart can be made as well.
Your veterinarian may also perform blood tests to look for any underlying medical condition that may be contributing to the heart disease and to ensure there are no metabolic problems present that will affect therapy.
How is DCM treated?
Unfortunately DCM is not reversible, although there are certain medications that may help for a period of time. Some of the more commonly used drugs are diuretics, drugs that may help increase the contractile ability of the heart, drugs that may decrease the heart rate or drugs that decrease the work that the heart has to do to function. Drug choices often depend on the status of your pet’s health and the signs they may be showing. Your veterinarian can help tailor a treatment plan that is most appropriate for your pet.
Even with optimal therapy, the long-term survival of patients with DCM is highly variable. Initial response to therapy may also play a role in determining long-term prognosis. Previous studies have indicated that DCM in Dobermans carries a worse prognosis than in other breeds however; it is ultimately a terminal illness.
A mammal’s heart is composed of four chambers. There are left and right atria and ventricles. These chambers act as 2 different pumps. The left side pumps oxygenated blood to the body and the right side pumps blood through the lungs so it can become oxygenated. The path blood travels through the body is from the lungs to the left atrium through the mitral valve and into the left ventricle. It is then pumped out through the aorta to the body. Cells in the body use the oxygen in the blood so the oxygen depleted blood returns to the right atrium via the vena cava. It goes through the tricuspid valve into the right ventricle where it is pumped out to the lungs to begin the cycle again.
Hypertrophic cardiomyopathy (HCM) is a heart condition characterized by a thickening of the muscle comprising the left ventricle of the heart. This decreases the size of the left ventricular chamber and means the heart has to pump more times per minute to pump a normal volume of blood through the body. This problem develops most commonly in cats. Most cats are diagnosed on physical examination when a heart murmur or abnormal heart rhythm is noted. Some cats go into heart failure when the lungs start to accumulate fluid (edema) and they can develop severe and life threatening breathing problems. The edema develops from blood backing up into the lungs causing fluid leakage out of the blood vessels.
Occasionally, cats may see their veterinarian after developing sudden paralysis. This occurs due to abnormal blood flow through the heart, which predisposes them to abnormal clot formation. These clots will begin in the heart, travel down the aorta and become lodged at the point where the aorta splits to supply blood to the hind legs (aortic thromboembolism). This obstructs blood supply to the hind legs and results in paralysis.
Although evidence is mounting that the cause of HCM may be genetic in origin, the exact mechanism is still unknown at this time. One disease that may be associated with the development of HCM in cats is hyperthyroidism. In some cases, treatment of the hyperthyroidism may correct the heart problem but some cats may require heart medication for a period of time before and after being treated for the disease.
In addition to a physical exam and lab tests, radiographs of the chest are also used in the diagnosis of HCM. The radiographs may be normal or show enlargement of the left atrium. Some cats even have a valentine shaped heart.
The diagnostic test of choice is an echocardiogram (heart ultrasound) which determines the size and shape of the heart chamber. Since high blood pressure (hypertension) can also be seen with HCM, the patients blood pressure is often checked as well.
All of these diagnostic tests help your doctor decide which means of therapy would be most beneficial to your cat. Cats that have heart failure or paralysis are treated much differently than patients with no symptoms. HCM is life threatening and aggressive therapy is often required in cases of heart failure or paralysis. Treatment of cats with aortic thromboembolism is often supportive and aimed at helping the heart pump more effectively as well as managing the pain caused by the clot. With time, some cats will recover the ability to use their legs. This may take days or even weeks, and prognosis is also dependent on the ability to manage their HCM. Some medications made specifically to destroy the clots have been used clinically and experimentally with mixed results. Unfortunately, despite treatment, clots often reoccur.
Cats with congestive heart failure are treated with a combination of medications and oxygen to decrease the congestion and to help the heart pump more effectively. The long-term prognosis is variable but with rapid and early intervention, cats with HCM are leading longer lives.