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Matters of the Heart

By Dawn Singleton-Olson
February, 2019

The basics of heart disease in dogs and cats, and the tests and treatments your practitioners need for their patients

Long before it was designated as Pet Dental Health Month, the month of February has been associated with all matters of the heart – from love and romance to a focus on human heart disease and prevention, thanks to American Heart Month. Years of public relations campaigns have raised awareness of heart disease in people, but when it comes to their animals, pet owners often aren’t familiar with the cardiac issues that can affect their pets. Knowing the basics of heart disease in dogs and cats and the tests and treatments your practitioners need for their patients will help you get to the heart of the matter as a valued resource for your customers.

There are six different types of heart disease in companion animals.

Valvular Disease: Heart valves normally form a seal when they’re closed, but with valve disease, one or more may “leak,” allowing blood to be pumped backwards. The backward flow creates a murmur which can be detected with a stethoscope. The abnormal valves can lead to heart enlargement. This form of heart disease usually occurs in small to medium-size dogs, and is the most common with 75 percent of cases. Most susceptible breeds include Cavalier King Charles spaniels, poodles and Chihuahuas.

Myocardial Disease: The heart muscle becomes weakened or thick. Hypertrophic cardiomyopathy is the most typical form of heart disease in cats, affecting one in seven felines. It thickens the ventricle walls and harms proper heart function, leading to blood clots, congestive heart failure or sudden death. Dilated cardiomyopathy is the second most common heart disease in canines, usually occurring in medium to large dogs. The contractions of the heart are weak and don’t pump blood efficiently. Typically, the heart stretches and enlarges, which further comprises the ability to move blood through the body. Susceptible breeds include Dobermans, boxers and English bulldogs.

Pericardial Disease: The protective sac around the heart fills with fluid.

Arrhythmias: A condition that causes an irregular heartbeat.

Congenital Disease: Animals born with a malformed heart that can lead to progressive heart enlargement. Congenital defects account for a small percentage of diagnosed heart problems.

Heartworm Disease: Preventable heartworm infestations can damage the heart, lungs and arteries.

Clinical discussions

The signs of heart failure can be subtle and mistaken for changes associated with aging, so it’s important for veterinary professionals to discuss heart disease and congestive heart failure with pet owners of at-risk patients. Clinical signs can include changes in and difficulty breathing, excessive panting or wheezing, lethargy, decreased appetite, abdominal swelling or distention, weakness, collapse or fainting, and in dogs, a persistent cough or increased coughing. (In cats, coughing is typically associated with lung disease.)

Over time, heart disease leads to decreased performance pumping blood through the body and causes congestion, or pressure buildup. The blood can’t move forward as it usually does, and builds up behind the problem area. The congestion builds up in the abdomen if the right heart is failing and in the lungs if the left side of the heart is failing. Fluid in the lungs fills the air sacs, making exchanging oxygen more difficult. The pet needs to take more breaths to absorb the same amount of oxygen, increasing breathing rate and effort.

Besides listening to a pet’s heart for evidence of a heart murmur, there are several diagnostic tests to assess cardiac conditions in animals showing clinical signs, including radiographs to view any abnormalities of the heart; blood pressure tests; electrocardiograms (ECG) to evaluate the electrical activity of the heart and diagnose abnormal heart rhythms; and echocardiograms which provide an ultrasound evaluation to assess valvular function, identify leaking valves and measure cardiac output.

Heart disease can also cause changes in the blood which can help to diagnose certain cardiac diseases in at-risk animals showing no clinical signs, measure the severity of the disease, and evaluate the effectiveness of treatment. The levels of several natural substances – or cardiac biomarkers – such as cardiac Troponin I and NT-proBNP increase in many types of heart disease and can be detected with a simple blood test. Electrolyte levels such as potassium, sodium or magnesium may be abnormal in animals with heart disease, and testing of kidney function – blood urea nitrogen (BUN) and creatinine is often done to ensure that medication doses are at optimal levels. Familiarize yourself with the diagnostic tests from the manufacturers you carry and be sure your customers are well stocked with any necessary add-ons for blood draws.

Treatments for congestive heart failure (CHF) don’t cure the disease, but help improve the quality and length of the pet’s life. There are a variety of medications and supplements to discuss with your customers.

Some of the most common medications used are angiotensin-converting enzyme (ACE) inhibitors that open constricted blood vessels in front of and behind the heart. These include enalapril (Enacard), lisinopril and benazepril.

Diuretics are very effective in treating CHF since they cause the excess fluid that has built up to be taken up by the kidneys and excreted as urine. There are several types, including furosemide (Lasix), hydrochlorothiazide (Microzide) and potassium-sparing diuretics like spironolactone (Aldactone).

Inodilators such as digoxin or pimobendan (Vetmedin) help to increase the force with which the heart muscle beats and open up constricted blood vessels to reduce the workload on a weakened heart.

For cats with hypertrophic cardiomyopathy, Atenolol or Diltiazem reduce heart rate and allow the heart to fill more adequately. Plavix has been used in cats to help decrease formation of blood clots.

Many veterinarians also recommend special diets and supplements, particularly Omega 3 fatty acids for long-term management of heart failure. Others include vitamin B, taurine, carnitine and antioxidants like Coenzyme Q and vitamin E.

Pet owners should understand the importance of watching for changes in appetite, behavior and activity. Monitoring respiration rates is an important – and easy – method of tracking a pet’s health. Your practitioners may want to recommend the Resting Respiratory Rate (RRR) app available from iTunes or the Google Play Store. It allows owners to set reminders to track their pet’s RRR, compare it over time, and upload the information directly to the veterinarian.

Heart disease is a frightening diagnosis for pet owners. As a resource for products, treatments and client information, you can help your customers improve the lives of their patients and build stronger relationships with their customers. 

Topics: Companion 2019 February Vol. 11 Issue 1, Heart Disease

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