While it may have felt like it was never going to happen, it appears spring is finally here in Perth County! With the arrival of spring brings the arrival of heartworm season! Here is some information to help you understand heartworm and why we feel prevention is important.
What is Heartworm?
Heartworm (Dirofilaria immitis) is a parasitic worm transmitted to dogs from mosquitoes. Heartworm-infected mosquitoes inject immature heartworms into the blood when they bite your dog. These worms then travel to the blood vessels around the heart and lungs, where they can grow into adults as long as 30 centimetres! Adult heartworms can cause serious and fatal problems such as congestive heart failure.
How would my dog get infected?
Your dog could be infected by a single bite from an infected mosquito. 
What are signs that my dog could have heartworm?
Dogs will show no signs of infection early on while the heartworm is growing. When the heartworm reaches an adult state, signs of infection may include cough, weight loss and exercise intolerance. Because heartworm infections may not show any signs until they have progressed very far, we recommend regular testing for heartworm. The testing is performed by taking a small blood sample that is examined by a Registered Veterinary Technician in our clinic laboratory.
What is the risk that my dog would contract heartworm disease?
While the risk is low, between 2002 and 2010, the incidence of heartworm in Canada has increased by 60%, with the majority of infected dogs living in Ontario. Also, most of the infected dogs were not on heartworm prevention medications. This increase is likely due to numerous factors such as increasing temperatures and an increase in dog adoptions from warmer climates. Furthermore, in Western Ontario coyotes can act as a reservoir for heartworm.
Why not just treat my dog if it gets it?
With heartworm disease, the saying “An ounce of prevention is worth a pound of cure” really holds true. Once a dog is infected with heartworm, the treatment is long, painful and can result in death. More serious infections could involve surgery to remove the worms from the heart. Prevention of heartworm is much easier and has fewer risks.
How do I prevent my dog from getting heartworm?
The easiest way to prevent your dog from getting heartworm is by placing your dog on a monthly heartworm preventive medication. These medications kill the immature worms that infect your dog and when used according to the label, are highly effective at eliminating these infections. Heartworm medications can have other benefits as well, such as preventing intestinal worms and fleas, depending on which product you use.
Here at Coventry Animal Hospital, our staff believes that prevention is the best approach to heartworm and all our pets are kept on monthly preventive medication through heartworm season. To discuss which product is best for your pet, contact us today!
We also recommend reading our blog update on Ticks.