Heartworm (French Heartworm)

Heartworm is a major parasite of dogs in many parts of the world and causes serious health problems in unprotected animals.

In Europe the 'common' form of heartworm (Dirofilaria immitis) is prevalent in areas around the Mediterranean and is spread by mosquitoes. Vets occasionally see this form of heartworm in imported dogs arriving from affected areas. However this may become more of a problem as UK dogs travel on mainland Europe under the Pet Travel Scheme.

In the UK a different type of heartworm is already present. Up until quite recently the parasite Angiostrongylus vasorum (French heartworm) was thought to be limited to certain areas in Cornwall and Wales. Only one case had ever been reported in the south-east of England but that all changed at the end of 1999 and through 2000 as veterinary surgeons were presented with increasing number of these cases.

Although most cases have occurred in dogs that are known to eat snails we have found a few cases where owners were unaware that their pets had this habit so do not think that just because you have never seen your pet eat a snail that they actually do not.

It is suggested that the most likely way that this problem has been spread is by the fox population for which snails and slugs make up an important part of their diet. The foxes in turn pass on the parasite back to the slugs and snails in their stools.

What is Angiostrongylus vasorum?
Angiostrongylus is a parasitic worm, the adult lives in the heart and arteries of the lung of the dog, fox and other animals that are affected by it.

How can your dog become infected?
This happens as a result of your dog eating a slug or snail that harbours the immature form of the worm.

Can my dog catch it from an infected dog or fox?
No, the only route of infection is from eating an infected slug or snail.

What are the signs of infection?
Some dogs with a subclinical condition (one which does not manifest itself outwardly) may have a low-grade infection for months or years without showing signs. However the most common signs of infection are rapid breathing and cough (occasionally blood is brought up). In more severe cases some dogs are presented in heart failure or collapsed and others show signs of bleeding problems.

What should I do if my dog starts coughing?
Don't panic! Take it to your vet. There are many reasons why a dog may start coughing. However if your dog is known to eat snails then a veterinary examination is definitely a good idea. If your vet is uncertain of the cause of the cough they will probably recommend doing various tests to investigate the cause. This may include chest x-rays, blood tests, stool analysis and obtaining samples of mucus or fluid from the airways in the lungs. Obviously if you have seen your dog eating slugs or snails remember to mention this to your vet.

Can this condition be treated?
If Angiostrongylus is identified early in the course of the infection anti-parasitic drugs can be used to treat it effectively. If complications have already occurred then treatment is less likely to be successful.

Can I prevent my dog from getting infected?
Yes, monthly treatment with an appropriate wormer obtained from Parkvets will be effective.

Prevention is so much better than cure so we recommend worming monthly with a prescription wormer containing Moxidectin or Fenbendazole.