Acquired heart diseases are those that a dog acquires during its lifetime, usually as a result of normal wear and tear, infection or injury.
Acquired heart disease accounts for 95% of all heart disease seen in dogs, and usually appears after they reach middle age.
By the time a dog shows obvious symptoms of acquired heart disease, it is likely that irreversible damage has already been done. Usually, the earlier heart disease is diagnosed, the better your vet will be able to manage the condition.
So, it's worth asking your vet to give your dog an annual healthcheck regardless. In this way, they'll stand the best chance of picking up any signs that you would not be able to spot yourself.
If your dog is diagnosed with an acquired heart disease, the outlook is not necessarily all bad. With the latest drug therapy, he may be able to live a comfortable life for some time to come.
Chronic valvular disease can be thought of simply as 'leaky valves', caused when the moving parts of the heart valves thicken and harden with age. The result is more or less the same as when a valve in your central heating system starts to wear out: increasingly poor circulation.
These valves may thicken or harden with age. This can either restrict bloodflow, or allow blood to 'leak' back past the valve.
If any valve is affected in this way, it will compromise the heart's ability to pump blood.
Although valvular disease can affect any dog, smaller breeds tend to be more prone. In particular, the Cavalier King Charles, Chihuahua, Miniature Schnauzer, Maltese, Pekingese and Whippet. Of these, Cavalier King Charles Spaniels tend to develop the disease earlier in life.
By far the most common form of myocardial disease is known as dilated cardiomyopathy (DCM). It affects the muscular walls of the heart and prevents them from expanding and contracting correctly. In most cases, the cause of the disease is unknown, although it has been associated with nutritional deficiencies, viral infections and certain medications. There is also thought to be a genetic link, since it affects some breeds more than others. Males are more commonly affected.
Failure of the heart muscle fundamentally affects the heart's ability to circulate blood around the body.
Although dilated cardiomyopathy can affect any dog, it is more commonly seen in certain large breeds, such as Dobermanns, Irish Wolfhounds, Great Danes, St Bernards and Newfoundlands.
The heart is triggered to beat by electrical impulses from the brain. If there is an interruption to this signal, the heart may cease to beat completely, with obvious consequences. More commonly, though, a patient will suffer from a condition that causes an irregular heartbeat, or arrhythmia.
We have classified arrhythmias within the acquired disease category, because this is thought to be the most common form. However, dogs with congenital heart disease or no underlying heart disease may also suffer from arrhythmias.
In some cases, the heart may simply cease to beat. In most cases, though, the heart will beat less effectively than it should, thereby reducing the volume of blood pumped around the body.
All breeds may suffer from different types of arrhythmia, but the following are known to be at higher risk: Cavalier King Charles, Pugs, Miniature Schnauzers, Boxers, German Shepherds, Dobermanns and Irish Wolfhounds.