Cat News You Can Use

Two CatsYears ago when I adopted my first cats, my veterinarian told me that unlike dogs, cats do not get heartworms, so I didn’t need to give my cats any preventive medicine for them.

However, fast forward about 20 years and now veterinarians know that cats, too, can become infected with heartworm. In fact, recently, the number of feline heartworm cases was thought to be on the decline. However, over the past few years, the number of feline heartworm infections seems to be increasing. The jury is still out on if the increase in the number of cases is the result of an increased number of infections, or if veterinarians have become better at diagnosing heartworm in cats as they have learned more about the problem.

So what is heartworm? According to a recent report in the November 2012 issue of “Catnip,” a newsletter published by the Cummings School of Veterinary Medicine at Tufts University, heartworm is caused by an infection of a parasitic worm named Dirfilia immitis. As it turns out, the disease is most commonly found in warm, muggy climates that are inhabited by mosquitoes that carry the heartworm larvae. As the mosquito flies from one animal to another, it bites and transfers the larvae to the animal, infecting it. The larva then develops and matures over a period of several months into worms that can grow to be nearly a foot long.

Eventually, the worms take up residence in the cat’s pulmonary arteries; these are the blood vessels that carry the blood from the heart to the lungs. In an advanced heartworm infection, the mature worms usually cause damage to the walls of the pulmonary arteries and also slow down the blood flow. This can cause abnormal strain on the cat’s heart with potentially fatal results.

Just like in dogs, heartworm is difficult to treat in cats and the treatment can be fatal. However, heartworm can be prevented. The key to prevention is to provide your cat year-round protection by giving them preventive medications such as selamectin, milbermycin, or ivermectin to all the cats you own. This is very important in our area because of our mosquito population.

If you have any questions about heartworms and your cat, please contact your local veterinarian for answers and advice. As always, before you give any kind of medication to your cat, check with your veterinarian for recommendations on the best products, dosage, and treatment schedule for your pet.

Wishing you, your family, and pets a Safe & Healthy 2013!!


“Short Takes – Heartworm On the Rise,” in ‘Catnip, The Newsletter for Caring Cat Owners:’ written by Cummings School of Veterinary Medicine at Tufts University. November 2012, Vol. 20, No. 11

(Bill Mahan is a FL Sea Grant Agent and Director of the Franklin UF-IFAS Extension Program. Contact him on Facebook:, via e-mail at, or at (850) 653-9337, 697-2112 x 360.)




Posted: February 4, 2013

Category: Work & Life
Tags: Cats, Health And Safety, Heartworm, January-March 2013, Panhandle-livingwell

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