Protecting Pets From Heartworm Disease

April is Heartworm Disease Awareness Month. And as temperatures in South Florida begin their seasonal climb, so too does the population of insects responsponsible for the spread of the disease - mosquitoes. In our tropical climate, there’s no better time to reacquaint ourselves with the basic knowledge of heartworm disease, and more importantly, heartworm prevention.

While cats can and do contract heartworm disease, they are not ideal hosts, and rates of infection are only 5%-20% of those compared to dogs in similar areas. Many cats affected by heartworm disease have only several, if any adult worms, as the worms will often die before reaching the adult stage of development. That said, even immature worms can cause profound damage in the form of Heartworm Associated Respiratory Disease. This condition often goes undiagnosed until the cat is gravely ill, and cannot be treated with the same medication used to treat dogs. Since feline heartworm disease is far more common and widespread than previously thought, year round prevention is the key to protecting cats.

Heartworm disease is a far greater threat to dogs, and from 2013 to 2016, diagnosed cases in the Southeast have been on the rise. Additionally, Florida is consistently one of the top ten states with the highest number of new cases every year. Clinical signs of heartworm disease in dogs include exercise intolerance, coughing, decreased appetite, weight loss, and fatigue after moderate physical activity. Left untreated, heartworm disease is usually fatal. To best protect our dogs against this common threat, it’s important to understand how the disease is spread, and how it can be stopped in its tracks.

There are several species of mosquitoes capable of transmitting heartworm disease, all of which thrive in South Florida’s warm, tropical climate. For transmission to occur, a female mosquito must first bite an infected host animal (host animals can include dogs, cats, ferrets, foxes, wolves and raccoons), then move on to feed upon another animal. As she feeds upon the second animal, the parasite is passed from the mosquito to the bloodstream. This is the point at which transmission occurs. Heartworm disease is not contagious, as it is only spread via mosquito bites and cannot be passed directly from one animal to another.

It takes roughly six to seven months from the point of infection for the parasite to develop into an adult heartworm. For this reason, dogs may show no clinical signs of illness until long after infection has occurred.

The best way to protect our pets from the danger of heartworm disease is by keeping them on heartworm prevention throughout the year. In my practice, I recommend products which are given in the form of a monthly pill. These products are palatable, inexpensive, easy to dispense and have proven track records of both efficacy and safety. While heartworm preventatives have traditionally been sold exclusively by veterinary hospitals, today’s veterinary client is drawn to the convenience of purchasing from online pharmacies. Bear in mind, however, that nestled in the fine print of product package inserts is a notice advising clients that these products may lose efficacy if exposed to temperatures over 86 degrees Fahrenheit for extended periods of time. In other words, if a box of heartworm prevention sits in your outdoor, South Floridian mailbox for the duration of your work day, it has likely been reduced to an overpriced cookie. Additionally, many pharmaceutical companies will not stand by their promise of efficacy once they know the product in question was purchased from an online pharmacy.

While I realize it sounds protectionist, it’s important to buy these products directly from your veterinarian in order to avoid the possibility of inadvertently giving your pet an ineffective product. By now, most veterinarians have priced their products similarly to their online competitors, so the difference in price may be less than you think. And if it’s not, don’t be afraid to ask your veterinarian to match the price.