Heart Defect (Congenital) in Cats

In a properly functioning heart, there are four chambers and four valves all moving deoxygenated blood from the rest of the body into the lungs to be re-oxygenated, then pumping oxygenated blood back to the body. A congenital heart defect is a flaw in any of the systems involved in this crucial function, and affects the way the blood flows through the heart and lungs, or the way the heart behaves during contraction and flexion.

Congenital heart defects are uncommon in cats. There is a wide variety of types and severities of congenital heart defects (CHDs) from benign forms to life-threatening ones. Some forms respond well to early intervention. It is recommended that all newborn kittens be examined by a veterinarian to determine if a CHD is present.

In cases where a cat is suspected of having a CHD, immediate veterinary attention is required.

The severity of congenital heart defects depend largely on what type of defect is present. Some defects, such as tetralogy of Fallot, are often incompatible with life unless treated promptly. Others, such as small ventricular septal defects, may resolve on their own without treatment. In some cases, the cat is born with a defect that does not cause symptoms or damage. Sometimes, the defect corrects itself over time.

In some cases, the defect is catastrophic and the kitten does not survive birth, or lives only a few days.

In some defects, the size of the defect affects the severity. For example, small ventricular septal defects cause very little disruption to blood flow, and cause mild or no symptoms, whereas larger versions of the same defect cause severe disruption and can be fatal.

Left untreated, many of these defects affect the function of the other parts of the heart, as well as the lungs. In these cases, the heart defect develops into congestive heart failure or irreversible heart damage. With heart failure, the lungs may become filled with fluid, making breathing difficult. Fluid may also accumulate in the abdomen, causing abdominal distention.

CHDs are caused by factors (or a combination of factors) that affect the mother and unborn kitten during pregnancy, including:

• Genetic factors
• Environmental conditions
• Poor nutrition for the mother
• Infections
• Toxicosis in the mother during fetal development

Possible heart defects include:

• Atrial septal defects
• Ventricular septal defects
• Mitral valve dysplasia
• Tricuspid valve dysplasia
• Endocardial fibroelastosis
• Patent ductus arteriosus
• Aortic stenosis
• Tetralogy of Fallot
• Pulmonic stenosis
• Cor Triatriatum Sinister

In many cases, there are no symptoms related to CHDs. Often, these cases are diagnosed when a heart murmur is detected by a veterinarian.

Diagnostic tools to identify the type of congenital heart defect include:

• Physical examination, including listening to the heart for murmurs
• Electrocardiography (examining the electrical output of the heart)
• Diagnostic imaging, including X-rays or ultrasound

Some heart defects respond well to medication. Others are treated with surgery. In many cases, there are no treatment options available, and cats may require euthanasia if their quality of life is poor,

The prognosis for cats with congenital heart defects depends on the specific defect that is present and the severity of the defect. In some cases, the cat lives a long and healthy life despite the presence of a defect. In cases where defects can be repaired surgically or managed medically, the prognosis is fair to good. In severe cases, congenital heart defects are fatal.

There are no proven preventative measures for CHD. Strategies to reduce susceptibility to congenital heart defects include:

• Keeping pregnant cats healthy and on appropriate diets
• Avoiding access to toxins or environmental contamination for pregnant cats
• Avoiding mating cats with CHDs

Congenital heart defects are uncommon in cats.

• Surgery
• Medication