Valve disease occurs when the valves that control blood flow in the heart wear out and become inefficient, allowing blood to leak against the flow. This leakage makes it much harder for the heart to pump blood around the body, and this leads to the classic symptoms of canine heart disease – weakness, lethargy, coughing and exercise intolerance. Weakness, lethargy and exercise intolerance are fairly obvious results of weak blood flow around the body, but the cough is caused by both the build up of fluid in the lungs and also the fact that the heart gets bigger to try to compensate for its inefficiency and ends up pressing on the windpipe inside the chest. As the disease progresses, dogs tend to get more and more severely affected by the symptoms, and if left untreated, the prognosis for dogs with valve disease is poor – they will often die within a year of diagnosis. Having said that, not all cases of valve disease are quite as serious as that, and some dogs can cope with this condition for many years with few adverse effects.

Diagnosing heart disease in dogs is usually relatively straightforward – the symptoms, combined with what we call the signalment (the breed, age, sex and history of an animal), and the findings of a clinical examination are usually sufficient to enable a diagnosis to be made. One of the key findings on an examination is a heart murmur, which is caused by the damaged valves opening and shutting noisily in the heart, and the loudness and location of the murmur usually helps define the seriousness and specific nature of the problem. Additional tests such as Doppler ultrasound scans and ECG’s are also used, particularly by cardiac specialists, to give a much more accurate assessment of the heart function.

Once valve disease has been diagnosed, there are several treatment options to consider. These are really variations on different regimes of medical therapy, as surgical options such as valve replacements are not yet available for dogs. There are 3 main types of drugs used for canine heart disease – ACE inhibitors such as Cardiovet and Fortekor which help lower the resistance in the circulation, diuretics including frusemide, and drugs that help the heart pump more efficiently including Vetmedin. The timing and exact regime used tends to vary from vet to vet, but in general if your dog is seriously affected, they are likely to end up on 4 drugs – and Ace inhibitor, Vetmedin and 2 diuretics.

The outlook for dogs with valve disease is not wonderful, with the average survival time after treatment has begun varying between around 3 and 12 months depending on all the variables. Early diagnosis and treatment are vital, so it is really important to have your dog’s heart checked on a regular basis, especially as they get older.

Heart disease is much less common in cats than it is in dogs, and the type of heart problem they suffer from is very different. Instead of leaking valves, cats tend to suffer from a problem called hypertrophic cardiomyopathy which is a bit of a mouthful but basically means ‘thickening of the heart muscle’. As this description suggests, this disease causes the wall of the heart to become thickened and this in turn restricts the ability of the heart to pump blood effectively. There are many contributing factors, but kidney disease and an overactive thyroid (hyperthyroidism) are probably the main risk factors as they both tend to increase the blood pressure and put extra strain on the heart.

Treating hypertrophic cardiomyopathy is not easy, but there are drugs such as B-blockers and calcium channel blockers that help. The outlook is not generally great, but if underlying health problems such as hyperthyroidism can be resolved, many cats can do reasonably well.