Often referred to as ‘the silent killer,’ heart disease affects about 10% of our dogs and cats, and because cardiac symptoms can be subtle, we may be unaware of the illness in our pets until serious damage has already begun. Often early symptoms are mistaken for natural aging processes, not thought of as a disease state  and consequently not mentioned to our vets.

EARLY SYMPTOMS OF HEART DISEASE*

• Decrease in appetite
• General slowing down
• Increased respiratory rate
• Coughing
• tired
• Occasional vomiting

MORE ADVANCED SYMPTOMS OF HEART DISEASE*

• Weight loss
• Weak, unable to do normal exercise
• Panting for no obvious reason
• Persistent, choking cough, often upon waking and at night
• Fainting with rigid limbs
• Swollen stomach and/or extremities

**Not all symptoms will manifest with all types of heart disease.

While most dogs are stoic about illnesses, cats are masters at hiding symptoms.  People rarely notice early signs of heart problems in cats, but if you observe cool extremities, open-mouth breathing, blue gums, or hind-leg paralysis, your cat is most likely already experiencing serious heart problems.

The heart is considered a muscular organ. The heart muscle is termed myocardium and contractability is one of its specialized functions. In total the heart is also an organ because it is a series of tissues working together for a function – pumping blood, hence it is a muscular organ.

Very broadly speaking there are four major types of heart diseases that most commonly affect dogs:

1. Congenital Heart Disease – Most articles about CHD have a list of around twelve common ailments with long complicated names that won’t mean much to non-medical people. These are conditions a dog is born with and they often have a strong genetic predisposition. They range in severity from mild heart murmurs to fatal illnesses.
2. Degenerative Heart Disease – As the body ages so does the hard-working heart. There are multitudes of heart conditions in this category, and they are often caused or exacerbated by environmental factors that we can control. Degenerative Heart diseases are rarely curable but most can be managed.
3. Heart Arrhythmias – These diseases can be either congenital or acquired. Heartbeats are controlled by an electrical chain of nodes inside the heart. These nodes stimulate the heart muscles to contract, pushing blood through the arteries into the body. There are at least six different types of arrhythmias found in dogs and cats, and the prognosis ranges from asymptomatic to sudden death in more severe arrhythmias.
4. Infectious heart diseases – Infectious Endocarditis is found in both cats and dogs. This happens when bacteria (from dental disease, UTIs, a skin wound, pyometra, immune suppression, etc.) migrate to the heart valves causing weakening and eventual malfunctioning of the organ. The second most common infection is caused by mosquitos and is more prevalent in dogs although cats can suffer from it, too. When an infected mosquito bites a cat or dog it deposits heartworm larvae into the bitten pet. The larvae travel to the heart and lungs then live and reproduce in those organs causing major heart damage and leading to death.

Cats can exhibit the same range of heart diseases as dogs, but most heart problems in cats take the form of Dilated Cardiomyopathy or Hypertrophic Cardiomyopathy. In Dilated Cardiomyopathy the heart suffers from general weakening and consequently pumps out less than normal blood. This causes the heart wall to stretch, enlarging the heart and eventually leading to death. In Hypertrophic Cardiomyopathy the left ventricle of the heart thickens, causing irregular heartbeats and oxygen starvation of heart tissues leading to eventual death. These conditions are often the cause of what appears to be very sudden cat deaths when in reality the heart disease had gotten progressively worse over time, but no symptoms were noticeable.

Yes, heart disease is a silent killer and one that most pet parents are not qualified to recognize. However, when caught in the early stages, most cardiac issues can be successfully managed, and your pet may live contentedly for many symptom-free years. In the next two installments covering this broad topic, we will discuss the causes of heart disease, the importance of veterinary diagnosis, increasingly sophisticated testing, and vet plus owner management of heart disease.

Happily, not all is doom and gloom. There are some important ways we can help prevent heart problems and improve our pet’s chances of living a long, healthy life even while having heart disease. Shakespeare wrote, “A merry heart goes all the day.” So too, our positive attitude and diligent care may give our pet’s hearts many more healthy days, months, and years to bless us with their companionship.