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Treating heartworm in dogs

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Intro Text
Heartworm is a particularly nasty parasite that is thankfully not present in the UK. However, if you travel abroad with your dog, he may be at risk. Learn about how you can protect your dog from this serious disease if you are taking him to parts of the world where it is present. And don’t forget that this parasite can affect cats too!

Dogs get heartworm from mosquitoes. A bite from an infected mosquito will transmit heartworm larvae into your dog; these larvae will grow and develop over a period of several months, and eventually become adult heartworms living in the major vessels of the heart and sometimes in the heart itself. Heartworm is not a problem in the UK, but elsewhere in the world this is an extremely serious and difficult to treat disease, so if you’re travelling abroad with your dog then taking steps to prevent it is vital.


In which countries is heartworm common?
Heartworm is not currently found in the UK.
However, it is common in many countries across the world. It is generally found in tropical and temperate regions, with the highest known prevalence in the USA, South America, Japan, Australia and Italy. It is also found in some other southern European countries such as Spain, Portugal, France, Greece and Turkey. Check with your vet if you are planning to travel abroad with your dog.

Symptoms can vary depending on the number of worms present; dogs with a low number of worms may show fewer symptoms, but high worm burdens can lead to coughing, tiring easily on exercising, and even heart failure.

Vets can diagnose heartworm in a couple of ways. The first is by testing the dog’s blood, and looking for microfilariae (microfilariae are produced by the adult heartworms, and circulate in the animal’s bloodstream). Another test can detect the presence of adult worms. Chest X-rays can also help to determine the extent of any heart and lung damage.

This condition is difficult to treat, largely because killing the worms can cause problems, as the dead worms can become lodged in the circulation.

Heartworm treatment firstly involves giving a drug to kill the adult heartworms; dogs need restricted exercise and supportive therapy during this time to avoid complications.

Once this has been achieved, a different drug is given that targets the stage of the heartworm that is circulating in the bloodstream (the microfilariae). Again, this is not without complications, as these dying microfilariae can lead to anaphylactic (allergic) reactions.

A range of additional therapies may be needed depending on the symptoms the dog is showing, and sometimes surgical extraction of worms is necessary when they are blocking blood flow from the heart.

Heartworm is an incredibly serious condition, and treatment can be costly and difficult, so the key if you are taking your dog to areas where this parasite is a problem is to try to prevent him becoming infected in the first place.

There are two ways to do this in dogs (and doing both together gives the best protection): first by using a product to repel mosquitoes, and second by regularly using a heartworm preventative product that will kill the larval stages of the parasite before they can become adult worms.

If you are planning on travelling abroad with your pet, speak to your vet about the necessary steps you need to take to make sure he stays protected.

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