How Heartworms are Transmitted

Heartworms can be indirectly transmitted from one pet to another through mosquitoes. When a mosquito bites an animal with heartworms, that mosquito becomes a carrier of the parasite. If it subsequently bites another animal, it can infect it with heartworms. Humans can even get heartworms from a mosquito bit, but they usually do not circulate to the heart in humans as they do with pets. For humans, the problem is infection of the lungs or eyes, though this is still a rare occurrence.



Heartworm Medications and Side Effects

For the most part, pets can use heartworm medication without a problem. In normal dosages, heartworm medication effectively kills off developing heartworm larvae without harming your pet. If you give your pet more than the recommended dosage, however, your pet can become ill. Certain breeds, such as Australian shepherds, shelties, collies, and border collies are particularly susceptible to illness from medication. For the most part, you would need to give your pet 10 to 20 times the recommended dosage in order to see negative effects.

Certain heartworm medications should be avoided with dogs with collie breeding, particularly medication intended to kill intestinal parasites in horses and cattle. Heartworm medications combined with intestinal worm medications, however, are safe if they are made for use with dogs. On the other hand, some pets can be allergic to chewable heartworm medication. The flavoring agents in the medicine often cause these allergies. Therefore, unflavored chewable heartworm medication is the best alternative.



How to Handle a Missed Dose

Missing a dose of heartworm medication, even for a couple months, leaves your pet susceptible to infection. If you do happen to miss two months of medication, you should resume your normal schedule. Then, you need to have your pet tested about seven months later, which is the amount of time it takes the worm to mature and to produce the special antigens your veterinarian will test for.

Pets living in areas with cold winters can skip medication during the cold winter months. It is, however, best to simply continue the medication throughout the year in order to prevent the possibility of missing a month. If you do choose to skip, be sure your pet receiving medication from June through November.