Cardiomyopathy (Boxers) in Dogs

Canines who are affected by cardiomyopathy may develop a  worsening condition as time progresses. Others live with the possibility of complications that never develop. A heartbeat that is off rhythm occasionally will not show distinct signs but if the condition is characterized by arrhythmias that become frequent or occur concurrently with other heart abnormalities, there is the very real danger that sudden death can eventually occur. Treatment and prognosis will vary from dog to dog; a diagnosis of ARVC can mean different things for you as a pet owner, depending on the severity of your pet’s condition. Abnormal heart rhythm, leading to a decreased flow of blood throughout the body will have a serious impact on your canine family member’s life.

The condition of cardiomyopathy in boxers is more definitively defined as arrhythmogenic right ventricular cardiomyopathy (ARVC). It is an inherited abnormality and is evident with arrhythmia of varying degrees. Because of this variance, some instances will be discovered upon routine physical examination, while other dogs may display very obvious and distressing signs.

If a boxer has a very mild case of arrhythmogenic right ventricular cardiomyopathy, he may not have visible symptoms at all. A dog with a more advanced stage of the disease may exhibit some or all of the following symptoms.

• Inability to exercise
• Fainting (syncope)
• Coughing
• Abdominal distention
• Stumbling
• Malaise
• Breathing difficulties
• Collapse
• Death

Types

Cardiomyopathy in Boxers can take on different forms which influence the impact they will have on your dog’s quality and length of life. A mild irregular heartbeat is one possible scenario. Episodic symptoms such as fainting or stumbling is the second progression of the condition, while sudden death is the third. A mild irregular heartbeat can eventually move forward as a more serious condition when complications arise. Researchers are not certain of a link, but it has been documented that some pets with ARVC also develop dilated cardiomyopathy whereby there are changes in the thickness of the heart muscle (becomes thinner), and the heart changes size (becomes larger).

ARVC is primarily related to the right ventricle of the heart but can also affect the left ventricle as it advances. 

• Electrical, structural, and functional problems may be evident
• There is a decrease in the blood flow throughout the body
• There are changes to the heart muscle to a fattier, fibrous tissue
• Abnormal genes have been identified

Your veterinarian will start with a physical examination of your furry family member as the process to identify the problem begins. The veterinarian may discover that your pet has a distended abdomen (ascites) which means there is a buildup of fluids resulting from the condition. Pulmonary crackles could be evident when the veterinarian listens to your pet’s chest with the stethoscope. Standard tests to begin with will be urinalysis, blood analysis, and chest radiographs to rule out other illnesses that may mimic cardiomyopathy. Conditions like neoplasia, metabolic disorder, stress, drug toxicity, and seizure disorder are all ailments that the veterinarian will consider as she goes through the diagnostic process.

Your pet’s medical history is important too, so be certain to relay pertinent information like recent illnesses, travel, behavioral changes or incidents that may have occurred such as the ingestion of a harmful substance. If you have records of your pet’s parentage, that could be useful also as the veterinarian delves into a genetic cause.

Three tests that are most valuable in determining ARVC are:

Ultrasound

An ultrasound of the heart may show abnormal changes and developments  in the muscle and size of the heart.

Electrocardiogram

This test shows the electrical function of the heart. However, it can mistakenly read as normal if the arrhythmia is intermittent.

Holter Monitor

This is a device worn by your dog over a 24 hour period, while at home. It monitors and records patterns and changes that can lead to a diagnosis of ARVC.

The treatment protocol could involve anti-arrhythmic therapy, meaning medications that will attempt to stabilize the inconsistencies in the beating and function of the heart. L-Carnitine and the benefits of it are still under study, but it is known that some canines with ARVC have an inherited deficiency of the amino acid. Omega 3 fish oil supplementation is thought to help pets who have this condition, but the reality is that a Boxer dog with cardiomyopathy will most likely succumb to the disease within weeks to months of diagnosis, depending on the stage of the illness and how quickly the problem progresses into a life threatening one.

If your canine family member has a mild case of heart arrhythmia, he could live for years with intermittent symptoms of occasional fainting episodes or on and off malaise. Many Boxers with ARVC are not quite so fortunate and though they can have a decent quality of life, you may see degenerative changes that progress from bad to worse. Many Boxers develop congestive heart failure as a secondary complication of ARVC.

A dog who has been put on medication to try and slow down or minimize the episodes of rapid or irregular heartbeat will need to have a follow-up of wearing the Holter monitor for another 24 hour period about three weeks after starting medication. As well, your veterinarian will determine the frequency of how often she feels your pet should be examined in order to receive the care he needs for the duration of his time with you.