Mosquitoes are responsible for transmitting several vector borne illnesses including heartworms. Heartworms are now endemic in North America, and are unfortunately very prevalent in the southern states, including North Carolina. Once transmitted by the infectious larval form by a mosquito, it can take up to 2 years for a heartworm to reach adult size and start reproducing. Heartworms live in the large blood vessels of the lungs, and males can grow up to 6 inches, while female heartworms can grow up to 12 inches. Heartworm disease can cause a cough, weight loss, pulmonary hypertension, pulmonary thromboembolism, kidney disease, congestive heart failure and acute death. Although we have several preventatives that can kill the larval heartworm stages, the only treatment available for a dog infected with adult heartworms is an adulticide containing arsenic. Unfortunately, there is no medical treatment for adult heartworms in cats, and they tend to develop an inflammatory response which affects their lungs and can result in sudden death. The American Heartworm Society and the Companion Animal Parasite council recommend annual heartworm testing for all dogs, as well as year round prevention for all dogs. When dogs are found to be positive for adult heartworms, it is recommended that they are staged (with bloodwork, thoracic radiographs, and microfilaria testing) and treated with adulticides as soon as medically practical. For this reason, your veterinarian will likely recommend that all dogs and cats be given heartworm preventatives year round from the time that they are 6-8 weeks of age and for the rest of their life.

Fortunately, we have several convenient options available to prevent heartworms. Heartworm preventatives for dogs come in injectable or oral form. The injectable form, Proheart, is very convenient as it can last for 6 or 12 months. Many pet owners choose a Proheart injection for their pets for the peace of mind of knowing that their pet is protected and they do not have to remember to give them a monthly pill. If your pet has a history of vaccine reactions, your veterinarian may recommend additional medications such as a diphenhydramine injection at the time of the proheart injection or an alternative form of heartworm preventative.

Combination preventatives are also very convenient. Simparica Trio is a chewable flavored tablet given by mouth that prevents heartworms, fleas, and ticks. It is given once a month and some pet owners like Simparica Trio because they can give their pet one product and know that their pet is protected for an entire month. If you choose to sign up with Zoets, the manufacturer will send you monthly reminders when your pet’s next dose is due.

Finally, there are budget friendly options such as Interceptor Plus. Interceptor Plus is a good option that prevents heartworms and also deworms your dog for hookworms, whipworms, roundworms, and tapeworms every month. This is a good option if your dog has a history of any of these intestinal parasites, or if your pet is exposed regularly by visiting dog parks or other lifestyle risk factors. Regular Interceptor is also approved for heartworm prevention in cats, but it lacks the praziquantel because the dosage is different for cats.

Finally, there are topical versions of heartworm prevention as well. Revolution Plus is a topical product for cats which is applied monthly and prevents heartworms, hookworms, roundworms, and ear mites. It also prevents fleas and ticks, so it is a good option for cats who go outside or who live with other dogs who go outside.

Please call your vet today to ask about heartworm preventatives for your pets! Click here to request an appointment.

By Brittany Holler Barkley, DVM