Cardiology

What is Heart Disease

Heart disease is defined as any cardiac finding outside of the normal limits. This can be an abnormal heart sound on auscultation, such as a heart murmur; an abnormality in the electrical conduction of the heart, seen on EKG; a reduced myocardial motion, seen on ultrasound. The proper functioning of the cardiovascular system is required to maintain normal blood flow, blood and capillary pressure as well as oxygenation to tissues. When heart disease progresses to a severe or acute state, the ability of the cardiovascular system to fulfill its function decreases, consequently causing more stress on the heart and other body systems. Heart disease can progress into heart failure if left untreated. 

Our hospital is equipped with advanced imaging systems to diagnose all types of heart diseases, such as:

Mitral Valve Disease

Mitral valve degeneration affects 10% of geriatric small breeds pets. It is also referred to as Myxomatous Mitral Valve Disease (MMVD), Chronic Mitral Valve Disease, Mitral Insufficiency, and Endocardiosis. MMVD is the most common cardiac condition seen in dogs. It is mostly, but not exclusively, a disease of smaller breed dogs and is seen in middle-age or geriatric dogs. The first sign of MMVD is a heart murmur, which can be heard during auscultation. 

Myxomatous Mitral Valve disease is due to an unidentified mechanism that leads to the deterioration of the Mitral Valves. The Mitral Valve is located in between the atrium and ventricle on the left side of the heart. Its degeneration causes the valves to retract and thicken, creating an opening through which blood can circulate back and forth within the atrial and ventricular cavities. The Chordae Tendineae (which anchor the Mitral valve and prevent it from moving freely in the atrium) can tear– causing the valve to flop back and forth instead of efficiently closing the atrio-ventricular communication. As the disease progresses, the vortex of blood inside the left side of the heart generates an acute left-sided congestive heart failure that is poorly responsive to medication.

Three-quarters of canine patients affected by a Myxomatous Mitral Valve Degeneration will not succumb to MMVD if properly treated due to the slow progression of the disease.

Heart Tumor, Hemangiosarcoma

The heart-based hemangiosarcoma exerts its life-threatening effects by bleeding. Tumors are generally located around the right side of the heart base (the auricle). The heart is enclosed in a sac called the pericardium. When the hemangiosarcoma bleeds, the blood begins to fill the pericardium–which presses against the heart and eventually compresses the heart, preventing it from filling and pumping adequately.  

This condition will degenerate into a circulating collapse named pericardial tamponade if allowed to progress. The only way to relieve the pressure into the cardiac sac is to perform a pericardial effusion, essentially taping the pericardium with a needle, therefore allowing the blood to evacuate to relieve the pressure around the myocardium. In 63% of cases of heart-based hemangiosarcomas there is evidence of metastatic disease (cancer that has already spread to other organs) at the time of diagnosis. Survival time after surgery alone is less than three months.

Cardiomyopathy

Cardiomyopathy (Dilated or Hypertrophic) is a primary disease of the heart muscle of the ventricles. Cardiomyopathies can occur in dogs and cats, and are more commonly seen in certain breeds. Some of the most commonly affected dog breeds include: Doberman Pinschers, Great Danes, Irish Wolfhounds, Portuguese water dogs, Dalmatians, Boxers, and Cocker Spaniels. Due to the prevalence of the disease in certain breeds, DCM has been linked to a genetic predisposition. Genetic mutations that are associated with DCM have been identified in Doberman Pinschers and Boxers. Genetic testing can be performed to identify the presence of the genetic mutation in these breeds.  

In some dogs, DCM can be caused by a nutritional deficiency, such as Taurine deficiency, an amino acid required for the development and function of the myocardium. Consequently, pets may develop DCM on taurine-deficient diets, such as vegetarian diets, and may benefit from appropriate supplementation.