Defect of the Ventricular Septum in Cats

Defect of the ventricular septum in cats is a relatively rare congenital heart disorder. Only about two percent of kittens will present with the condition. The defect is a hole in the ventricular septum of the heart, allowing blood to flow from one chamber to another. It is necessary to treat a congenital heart defect as early as possible, because the condition may progress to congestive heart failure, renal failure and premature death.

Some individuals will show no clinical signs of the disease, and radiology will exhibit no evidence of it. The cat with no outward signs may present with a soft, whooshing heart murmur when examined by a veterinarian. 

Some cats will show symptoms in varying degrees. These include:

• Fainting
• Intolerance of physical exertion
• Cough
• Difficulty breathing
• Pale gums
• Increased heart rate

Ventricular septal defect is caused by abnormal heart development in the kitten before it is born. Causes include:

• Unknown genetic defects
• Infections
• Poison
• Poor maternal nutrition
• Conditions within the environment
• Medication given the mother
• A combination of the above

Diagnosis of defect of the ventricular septum in cats begins with review of the medical history of the cat. Behaviors considered alarming or abnormal, such as frequent open-mouthed panting, are recorded. The veterinarian will ask questions about the developmental history of the kitten, and compare its size to an average feline of the same age. A stethoscope is used to listen to the heart and lungs and identify sounds of blood shunted through a defect in the pericardium.

Imaging techniques may be recommended, such as X-ray, echocardiography and electrocardiogram. A physical examination and X-ray often shows enough evidence to come to a diagnosis. If the diagnosis is undetermined, echocardiography is an excellent procedure to confirm defect of the ventricular septum.

Sometimes small holes in the pericardium will close with monitoring and no special treatment. A small hole that remains open will allow only a small amount of blood to flow through it, and will not become life-threatening or restrictive to the animal.

Pulmonary Artery Banding

A promising procedure is that of pulmonary artery banding. The surgical banding heightens pressure in the right ventricle which then restricts blood flow into the left ventricle. 

Palliative Measures

Large ventricular septal defects may be palliated with a medication like enalapril to slow blood flow from the left to right ventricle. This procedure is a stop-gap measure, because evidence of delayed congestive heart failure (CHF) is small. Congestive heart failure is the outcome of untreatable defect of the ventricular septum in cats. If CHF does develop, medicine such as furosemide, a diuretic, can be administered to slow fluid buildup. 

Long-term prognosis is excellent for kittens with a small ventricular septum defect, and an average lifespan can be expected. Monitoring with scheduled veterinary examinations is advised.

If a banding procedure for those with large ventricular septum defects is performed after early diagnosis and successfully lowers blood flow through the defect, a normal lifespan is possible with frequent monitoring from a veterinarian. Because there is some success for this procedure in kittens, the surgery is considered a viable option in some cases.

Monitoring Congestive Heart Failure

Medical therapy for those cats diagnosed with heart failure is diuretic medication if symptoms present. The symptoms of congestive heart failure are:

• Gray or blue tongue and gums
• Poor appetite
• Tiredness or weakness
• Rapid breathing
• Hind leg paralysis
• Sudden collapse

All of these symptoms are emergencies needing professional assistance.

Once the emergency conditions are stabilized, it is important that an ongoing course of medications be administered. The condition is not curable, so management of conditions with a view towards comfort and quality of life is preferred. 

It will be necessary to monitor kidney health through follow-up visits to a veterinarian, because the kidneys are overworked with the amount of fluid collected in congestive heart failure.

Managing Co-occurring Renal Failure

Managing renal failure in a feline means an alert assessment of symptoms. At first, the failure will show no visible signs to the observer except, possibly, the lethargy inherent in heart failure. Later, symptoms of weight loss, excessive urination and possibly vomiting may occur. 

Conservative palliative treatment is the answer to both congestive heart disease and renal failure, as they are tandem conditions stemming from a defect of the ventricular septum. 

Provision of adequate hydration is important, combined with palatable nutrition. Medication may be given to quell nausea. Vitamin D, Vitamin B and omega-3 fatty acids are believed to extend the lives of cats with chronic kidney disease.

A close partnership between veterinarian and caregiver is necessary to provide proper comfort and care for cats with a septal defect too large to treat.