Heart Healthy

By understanding the issues associated with heart disease and diagnosis, distributor reps can ensure their customers are well prepared to care for their patients.

By Laura Thill

Ensuring heart-healthy pets calls for regular preventive care checkups and an ongoing relationship between veterinarians and their patients. True, there are specialists in veterinary cardiology who are experts in the diagnosis and management of heart disease. But, it is often the general practitioners who man the front line of care.

     When it comes to heart disease, the good news for dogs and cats is that, compared to humans, they are equipped with a better network of arteries that feed the heart muscle. Whereas people have two central arteries, which are prone to becoming clogged by fatty foods, dogs and cats in particular are not susceptible to coronary artery disease. Still, they have their own set of concerns.

     Two types of heart disease that typically affect dogs are degenerative valve disease (also known as myxomatous valvular disease and chronic mitral valve disease) and dilated cardiomyopathy (DCM). The more common of the two, degenerative valve disease, typically affects smaller dogs at around nine years of age. The mitral valve is located on the left side of the heart, between the left atrium and the left ventricle. When the left ventricle contracts, the mitral valve must be in the closed position to force blood through the arteries to the rest of the body. Over the years, the mitral valve can wear out and become leaky in older dogs, and the blood is channeled back into the atrium. As such, cardiac output is reduced and less blood is circulated throughout the body.

     Degenerative valve disease is progressive. In its early stages, dogs may resist exercise, quickly run out of breath and develop a heart murmur. Later, they may develop a soft cough while lying down at night. In the final stages of the disease, the lungs become congested, causing dogs to have trouble breathing. Because the disease generally affects older dogs, pet owners may misinterpret symptoms as a product of age, notes Andrew Beardow, DVM, Boehringer Ingelheim.

     Dilated cardiomyopathy is a disease of the heart muscle that results in the thinning of the heart walls, weakened contractions and less effective pumping ability. Although dilated cardiomyopathy commonly affects larger breeds of dogs at around seven to nine years of age, it also affects some smaller breeds, such as Cocker Spaniels. Its symptoms are similar as those of mitral valve disease.

     Cats, too, are susceptible to heart disease, the most common of which is hypertrophic cardiomyopathy. The walls of the heart thicken, making the heart an ineffective pump. Because cats do not present a heart murmur and they sleep a lot whether healthy or sick, there often are no early warning signs. By the time the disease is discovered, it often is in its end stage.

 Frontline screening

Treating pets for heart disease means knowing not only when and how to treat, but when a disease should actually not be treated, according to N. Sydney Moise, DVM, MS professor of medicine, Cornell University, College of Veterinary Medicine. “Heart disease is often over-treated,” she points out. For instance, in the case of certain medications, timing can be critical. In addition, some animals may be at risk for heart disease, but not require medication for another couple of years. On the other hand, veterinarians must not rely on the notion of only treating a dog that has clinical signs. “We cannot know when a dog has symptoms, as they cannot speak and tell us how they feel. Consequently, dogs may need treatment before it is apparent to the owner that a problem exists,” she says.

     Particularly since many dogs and cats do not present clinical signs of heart disease early on, veterinarians need to examine patients and screen for the disease on a regular basis, Moise continues. “There is a lot of cardiac disease that can be managed in a primary care setting,” she says. “But, veterinarians must have a true understanding of the disease, and they must know where their comfort level is,” she adds, noting that it’s imperative that general practitioners know at what point they should reach out to cardiac specialists.

     A basic cardiac exam begins with a routine physical. A good stethoscope enables the veterinarian to detect heart murmurs as the blood moves in the wrong direction across the heart. In the case of a leaky valve, the veterinarian can get an idea of which valve is leaky and to what degree.

Although the stethoscope is a necessary tool for detecting heart disease, there are a number of devices available for diagnosing it, including the following:

• X-ray and/or radiography. X-ray and radiography provide a silhouette of the heart, enabling the veterinarian to see its size and whether the lungs are congested. However, the interpretation of an x-ray or radiograph is subjective, and if the animal is not positioned just so, the veterinarian may miss important signs. Also, in cats, the heart muscle expands equally on all sides, making it difficult to diagnose based on a silhouette image.

• BNP biomarker. At least one company offers a blood test designed to help diagnose or rule out heart disease in dogs and cats. It reportedly also helps differentiate heart disease from heart failure, and respiratory disease from heart disease. Because the test can be run in the veterinarian’s office, the veterinarian and client are provided with important information during the initial exam. Particularly for cats, who display no early warning signs of heart disease, a BNP test provides a dependable screen.

• Echocardiogram (ECG). Depending on the results of the x-ray or radiograph, the veterinarian will refer the patient to a cardiologist for an ECG, which can determine the existence of a cardiac arrhythmia or abnormal heartbeat.

• Doppler ultrasound. A noninvasive test that can be used to measure blood flow and blood pressure by bouncing high-frequency sound waves (ultrasound) off circulating red blood cells. (Whereas a regular ultrasound uses sound waves to produce images, it can’t show blood flow.

 As in the case of many diseases, diagnostic tools such as the above should be used in combination with one another to ensure the most accurate diagnosis. Veterinarians should begin with a general exam, including listening with a stethoscope for a heart murmur, says Beardow. They can follow up with a chest x-ray and a BNP biomarker. “The value of doing a chest x-ray – possibly every year [for high-risk pets] – is that it allows veterinarians to follow their patients closely and detect signs of heart failure early,” he explains. “We can follow the progression of the disease closely and know when the time is right to begin treatment (e.g., drugs).”  When necessary, veterinarians should follow up with an ECG, he says. “Many practitioners can do an ECG at their own practice,” he points out, noting that some veterinarians have anesthetic monitors with the capacity for ECG monitoring as well. And while some do have ultrasound, they often reach out to a specialist for this, he adds.

    Sometimes, veterinarians’ lack of awareness or financial concerns prevent them from adding new devices to their practice. Distributor reps may ask several questions, such as the following, to get their customers thinking about the value of diagnostic tools:

• “How do you currently examine and diagnose your cardiac patients?”

• “How do you evaluate heart murmurs?”

• “How do you determine which of your patients should visit a cardiologist?”

• It is especially important to focus on when each test or tool should be used and why it is applicable.

Newer treatments, better results

One of the biggest changes in the treatment of heart disease in recent years has been the more frequent use of pimobendan, a positive inotrope (a drug that improves heart function in cases of heart failure, heart attacks and various types of heart disease). While it has previously been used to treat animal heart disease in Europe, the drug only recently gained approval for use in the States.

     There are a number of large studies to support the use of pimobendan, says Beardow, and distributor sales reps can do their customers a service by keeping them apprised of such studies. For instance, the QUEST study – Quality of Life and Extension of Survival Time – is one of the largest global clinical studies involving dogs with congestive heart failure, he points out. The study, published in 2008, found that dogs with congestive heart failure receiving pimobendan plus furosemide (a diuretic used in the treatment of congestive heart failure) had significantly better outcomes than those receiving benazepril (an ace inhibitor) in combination with furosemide.

     “QUEST is a relatively new study that was published in the Journal of Veterinary Medicine, which not many general veterinary practitioners read,” says Beardow, adding that sales reps can become acquainted with the study and help educate their customers.

     Moise agrees. In order to keep their veterinarian customers up to speed on the latest advances in heart disease, distributor sales reps should become well acquainted with studies and attend conferences, she notes. Veterinary medicine is a fast-paced industry and new drugs are constantly being developed. “The drugs that work today will not necessarily be the ones we rely on five years from now,” she points out. As busy as veterinarians are, it’s imperative that they stay on top of the industry and its issues, she adds. Distributor reps can help them do so. “It calls for constant vigilance. We are all in the same boat [working to stay current].”