Seasonal Information

What is Heartworm Disease?

Heartworms are 8” long spaghetti-like worms that live inside a dog’s heart and can cause potentially life-threatening heart disease. These adult worms produce hundreds of microscopic larvae that circulate in the blood of the infected host (dog, coyote, fox, wolf). Heartworm disease is transmitted when a mosquito bites and ingests blood from an infected host and then later bites an unprotected dog thus passing the larvae along.  Over the ensuing 6 months the larvae travel to the heart and develop into mature worms. Unfortunately we cannot rely on the absence of clinical signs to consider your dog free of heartworm, and the earlier they are detected, the better the chances are for recovery.



Six months or more after transmission via a mosquito bite, heartworm disease can be diagnosed using a simple blood test. If your dog has been through a summer season without the benefit of heartworm preventive medication, a heartworm blood test should be performed before initiating preventive measures. If your dog has symptoms of heart disease (coughing, laboured breathing) a heartworm blood test may also be indicated. Intermittent heartworm testing is also recommended for all dogs on preventive medication (once every 2 years) in order to confirm compliance.

Please speak with our staff if you are unsure whether your dog is due for a heartworm test.



Although the incidence of heartworm disease in dogs living in the Oakville area is low, because of the severe nature of the disease, we do recommend preventive measures for your dog. At this time there is no effective vaccine that can protect dogs against heartworm disease, as there are for diseases such as rabies and distemper. However, there are several safe products available that effectively prevent heartworm disease. They come in a variety of formulations all of which are administered once monthly for 6 months during the mosquito season (first dose June 1st, last dose Nov 1st). There are several differences between the products used to prevent heartworm disease. Some are given orally, and others are applied topically. Some will provide additional protection against other parasites such as fleas, ticks, mites and intestinal parasites. Our veterinarians will help you decide which preventive medication best suits your dog’s lifestyle.



Advantage Multi:





If you would like more information about heartworm disease online, please see




Ticks have become increasingly common in our area in recent years. Some ticks have the ability to carry and transmit infectious diseases, such as Lyme disease, to dogs and to humans. Ticks are most numerous in the spring and fall but can be acquired anytime from March to December. There are some very effective products available to help protect your pet against infestation with ticks.

  • Nexgard is a prescription medication formulated into a flavoured tablet that will kill fleas and ticks for one month following administration. It can be used in combination and given simultaneously with any heartworm preventive medication but most commonly is paired with Heartgard Plus.
  • K9 Advantix is a topically applied medication that will kill fleas and ticks for one month following application. It can be used in combination with any heartworm preventive medication. When used along with Advantage Multi, they are applied alternately once every 2 weeks.

Regardless of which tick and flea medication is used, because ticks become active at temperatures of 4 degrees Celsius and higher, in some cases it is wise to initiate preventive medication starting in March.

K9 Advantix:


If you would like more information about Lyme disease, please see:




Fleas continue to be an extremely common warm weather skin parasite of dogs and cats. In an allergic pet, even one flea can cause severe dermatitis, itch and discomfort.

Fleas become active outdoors when the temperature rises above freezing in the spring, with the peak in flea numbers occurring in August and September. Winter weather provides some relief by reducing the outdoor flea population but fleas will thrive indoors over the winter months if allowed.

Fortunately, there are several flea control products available for dogs and cats that are very effective, very safe, and very simple to administer. Some of these products also provide protection against other parasites, such as heartworms, intestinal parasites, mites and ticks. Please ask us which flea control product best suits your pets needs.


Products recommended for dogs:

K9 Advantix:


Advantage Multi:




Products recommended for cats:


Advantage Multi:




If you would like some answers to commonly asked questions about rabies, please see: