The proper name for dog heartworm is Dirofilaria Immitis. Dog heartworm is a small thread-like worm that is a parasite in the hearts of dogs that is transferred through mosquitos. Last year we had a case of heartworm in our clinic, and it is an issue along the Grand River and towards Windsor.
Once the weather here gets above 14 C mosquitos can carry heartworm. We are fortunate that we have the winter/offseason meaning that heartworm is not such a large issue all year round. If you lived in an area where it is warm longer heartworm is an all year concern.
It all starts with a mosquito getting a blood meal from a dog that has heartworm disease. While it is drinking the blood, it pulls up the microfilaria (little worms) with it. When it then goes to take a blood meal from your dog, it injects some of them into your pet with the anti-coagulant it has to keep the blood flowing. It only takes one bite to pass it around.
If undetected your dog can have severe issues as the worms flow around the bloodstream and become large adult worms in the heart. This process takes at least seven months; then at this point, the adult worms are able to reproduce and have microfilaria in the bloodstream to cause issues in your pet. The adult worms can grow to be up to 30 cm in length.
Both the worms themselves and the little microfilaria can cause health issues. They travel through the bloodstream and cause problems especially in the lungs and heart.
Initially, there are no symptoms, but gradually they show up as a cough, decreased exercise tolerance, increased heart sounds and trouble with blood flow. If left untreated it will eventually kill the pet.
We can treat heartworm though it is painful and costly. It will involve many diagnostics including blood work and x-rays. The treatment itself consists of a hospital stay with sedation and injectable medications. Medications for the home will be added as well. Often if it is not too heavy a burden the dog can do well post-treatment for many more years. Heartworm is a large concern when adopting a pet from the southern states as they have a lot more of it.
The easiest way to avoid heartworm disease is through prevention. After a routine blood test is done in the spring (April – July) to ensure your dog doesn’t currently have heartworm disease (here we run a 4Dx test – this is also able to check for several of the tick-borne diseases) you can put your dog on a monthly preventative medication that will kill off the larva before it has a chance to become settled in the heart and become a full-blown worm.
In our area, we can use the product from June to November to take care of most of the issues. If, however, you travel to the US or we have a warmer year we can most certainly safely treat heartworm for longer.
Please consider getting your dog tested and on prevention to avoid this disease.
Written by: Manitou Animal Hospital