When Should I Start Treating My Dog With Preventative Heartworm Medicine?

By lexutor Sep18,2022

When Should I Start Treating My Dog With Preventative Heartworm Medicine?

The parasite

Heartworms are big parasites that can infest your animal, especially dogs, but sometimes cats as well. These very large parasites can measure up to 14 inches long! These worms, once they reach their adult lives, heartworms migrate to the heart and pulmonary arteries of the animal. Although some animals will leave with heartworms with no to little symptoms, most animals will show symptoms such as loss of appetite, coughing, difficulty to breath, shock, vomiting, diarrhea and in the worst cases, a heartworm infection can lead to the sudden death of the animal.

The infection

Worm go through an intermediate life stage which usually occur in the mosquito. The larvae infects a mosquito when it bites an infected animal. After a 2-week development, the larvae is ready to infect a new animal, which occurs when the mosquito bites another animal. It can take up to 6 to 7 months for the worm to fully develop and infect the heart of the animal.


Prevention is always best when it comes to heartworm medicine. Of course, it is possible to treat your dog after it has been infected, but preventive treatments are usually much more convenient and affordable. There are many ways to prevent heartworm infection: chewables, tablets, topical treatments (normally every month) and vaccines (generally every 6 months).

When should you start prevention treatment

This will depend largely on where you live. If you live in warm and humid area, where you mosquitoes are ready to bite all year-round, it is preferable to treat your dog year-round. If you live in a region where winters are cold, you can either decide to treat your animal throughout the whole year or start the treatment slightly before mosquito season starts.

Heartworm preventative medicine are also often good to fight other parasites (roundworms, ticks, fleas, etc).

By lexutor

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