Heartworm – The broken heart that is easy to prevent

One can’t help but notice that “prevention is better than cure” is a common theme throughout most of our articles. While there are some parasites and diseases against which one can do very little, there are many others that can be prevented with a dose of good will and common sense.

Heartworm is one such case. Scientifically known as Dirofilaria immitis, it is a parasite that infects dogs and cats throughout the world. It can be found in: North and South America; Southern and Eastern Europe; European Russia; most of Asia; Australia; and some African countries. It is also suspected to be present in Middle Eastern countries, but not enough information is available to back that claim. With the stakes as high as they are, and with the distribution of the parasite and the growning international animal trade, we do not feel that one should take their chances.

The dog is also a natural host for heartworm, which is able to complete its whole life cycle and multiply within the same host. Therefore, it is not uncommon that dogs can have great numbers of these parasites living in their system.

How do they end up in my dog?

You might think that keeping your dogs’ surroundings spotless and giving them a regular bath, would absolve you from any other preventative measures. Unfortunately, the parasite’s vector is the mosquito, and no amount of cleaning will build the much needed barrier between them and your pet. After being bitten by the mosquito, the heartworm deposits itself and develops inside the respiratory and cardiac system of the dog and their related blood vessels.

How do I find out if my dog has heartworms?

Unfortunately, it is impossible to see these worms with the naked eye. Only a veterinarian can perform the necessary tests to confirm the presence of heartworms in your pet. There are several symptoms that can indicate the possibility of these parasites infesting your pet. A heartworm infection can often result in a constantly coughing, lethargic dog with decreased appetite. If the infection is left unchecked, it is common to start seeing symptoms characteristic of heart failure starting to set in, the most obvious being an enlarged fluid filled belly. In extreme cases, large numbers of worms could lead to an obstruction of one or more of the heart’s vessels resulting in cardiovascular collapse. This is better known as caval syndrome; its symptoms are laboured breathing, pale gums, and dark or blood coloured urine. Depending on the stage of the infection, the dog might need to undergo surgery to remove the worms from the affected organs and tissue.

How can I prevent and treat this condition?

Heartworms take approximately 7 months to develop to a point where they can be detected by the antigen or microfilaria testing methods. Puppies under 7 months are therefore not tested for heartworm and only given preventative treatment. Puppies not on preventative treatment are tested at 7 months of age and then tested again at approximately 1 year of age. The tests are then to be repeated annually for the rest of the dog’s life. In case of the owner or veterinarian changing the type or brand of preventative treatment, the dog needs to undergo testing before and 6 months after the application of the product. If the tests show that the dog is indeed infected, it is best to confirm the diagnosis by testing again. It is also wise to reduce exercise and stabilize the condition of the dog. The dog also needs to be given the appropriate treatment and then tested again to see if the treatment was indeed successful. Preventative treatment can be given orally in the form of tablets, spot on treatment or through a slow release subcutaneous injection.