Irish Wolfhound Heart Disease

Courtesy of  Dr Serena E. Brownlie PhD BVM&S MRCVS Cert SAC

Heart disease in Irish Wolfhounds has been the subject of an on-going research programme in the UK since 1986. To the end of April 2013, data has been obtained from over 1800 Wolfhounds and many have been examined on several occasions, giving over 3200 separate examinations. Serious heart disease has been diagnosed in 280 dogs (15.6%). Despite all this data, there are many questions still to be answered. However there are some facts that every Wolfhound owner should understand:

There is a big difference between heart disease and heart failure. Many Wolfhounds live for years quite happily with hearts that are technically not quite normal and may eventually die of another disease. However once the problem becomes severe enough that the dog is unable to cope with it, drug treatment will be required or the dog will die. It is believed that it is an acquired disease, not congenital (ie not something the dog is born with). Symptoms of heart disease include rapid weight loss, breathing difficulty, abdominal swelling, collapse and sudden death. However it is important to remember that there are other diseases that may cause similar signs, therefore the condition should be diagnosed by a veterinary surgeon, preferably a veterinary cardiologist.

Every wolfhound that has developed heart failure has had an irregular heart rhythm called atrial fibrillation. This is the “hallmark” of heart disease in the Irish Wolfhound. Although we hoped to find another cause, the sad fact is that the tendency to develop atrial fibrillation appears to be inherited and it may not develop until the dog has already produced offspring. Although the genetics is not yet clear-cut, it is likely to be associated with an autosomal dominant gene, or group of genes. This means that an affected dog will transmit it to 50% of his or her puppies. If all wolfhounds developed heart disease in old age, it would not be regarded as a problem. Unfortunately it may develop in quite young dogs (sometimes under 2 years old). Affected littermates can develop problems at different ages, and just because a dog did not develop heart disease until old age does not mean that its progeny will be similar. Our data shows that males are more likely to be diagnosed than females, but it does not appear to be “sex-linked”. Males seem to develop the disease at a younger age and therefore it is perhaps more likely to be picked up at screening, especially if breeders do not heart test their dogs beyond breeding age. There may still be other factors involved of course – we are interested in the effects of nutrition, the immune system and viral infections.

Although no-one has a crystal ball to predict what will happen in the future, yearly heart screening is the only way currently available to detect a problem, and this is advised for all wolfhounds, especially breeding dogs. It is recommended that dogs are examined by stethoscope, electrocardiography (ECG) and echocardiography (ultrasound). Some hounds will have an “equivocal” test ie they will have a minor abnormality which may or may not progress. There is unfortunately no treatment which will prevent progression to heart failure, but heart rate can be controlled, some dangerous rhythm abnormalities can be treated to prevent sudden death and heart failure can be detected early, so even for pet dogs it is a good idea. By taking part in screening, your dog will also be providing further research information which will benefit the breed.