Can I Skip Heartworm Medicine in the Winter?

Heartworms are transmitted by mosquitoes. When the weather turns cold and you don’t see many mosquitoes, it is tempting to skip heartworm prevention medicine. Keeping your pets on heartworm prevention medicine all year long is an easy and important way you can keep them healthy.

Can i skip heartworm medicine in the winter? Heartworms are transmitted by mosquitoes. When the weather turns cold and you don't see many mosquitoes, it is tempting to skip heartworm prevention medicine. Keeping your pets on heartworm prevention medicine all year long is an easy and important way you can keep them healthy.

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Can I Skip Heartworm Medicine in the Winter?

We strongly encourage all pet owners to continue giving heartworm prevention medicines to their dogs and cats all year long. We do see dogs and cats with heartworm disease in our practice every year. These incidence maps from the American Heartworm Society show that we are in an area with a high number of cases of heartworm disease.

We have our share of strange weather here in Indiana. We might have a high of 65 degrees one day, and a low of 30 degrees two nights later. With weather swings like this, it is very difficult to predict what the mosquito population will do. It doesn’t take many days of warm weather for mosquitoes to be out and about again. Any time there are mosquitoes around, it is important to have your pets on a regular heartworm prevention medicine.

Even if you do live in an area that gets – and stays – cold for the winter months, traveling to a warmer area with your pet means that you should continue to give him heartworm prevention medicines. We are worried about what the mosquitoes are doing where your dog or cat is right now, not where he lives for most of the year.

We talk about heartworm prevention medicines as if they prevent your dog from getting heartworms. That’s sort of true… but not exactly. Your dog can be bitten by a mosquito at any time. If that mosquito is infected with heartworms, it will pass heartworms to your dog. The heartworm “prevention” medicine that you give your dog will kill the heartworms before they have a chance to develop into adults and cause problems in your dog’s heart and lungs. So the prevention medicine doesn’t exactly prevent your dog (or cat) from getting heartworms, but it does prevent her from getting heartworm disease.

If you give your dog her dose of heartworm prevention on October 1, and she gets bitten by a mosquito on October 10, but you don’t plan to give her another dose of heartworm prevention until April 1, she could very easily get sick with heartworm disease over the winter.

Most heartworm prevention medicines don’t just protect your dog (or cat) from heartworms. Some are also flea and tick prevention, and many protect against other intestinal parasites. Depending on the weather, these bugs and worms can be around in the environment all year long. Keeping up your dog’s protection against intestinal parasites (worms) is an important part of keeping him healthy.

Most companies that make heartworm prevention medicines will guarantee their medicines. If you have given your dog heartworm prevention every month – and you have purchased the medicine from your veterinarian – the manufacturer will pay for the cost of heartworm treatment if your dog does develop heartworm disease. If you or your veterinarian can only show that you purchased 10 doses of prevention over the last 12 months, the company will not cover the cost of treatment.

Remember, heartworm prevention is not only for dogs and cats who spend time outside. Mosquitoes can fit through screens or get in through open doors. When the weather turns cold, they are looking for ways to get warm! Make sure that your inside pets are protected, too.

Do you want even more information about heartworms? Check out our heartworm resource page. If you have a question that isn’t answered there, call us or come in. Our veterinary technicians and veterinarians will be happy to talk to you about heartworm disease, heartworm prevention, and the right prevention choice for your pets.

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