Heartworm disease is a chronic, life-threatening disease that affects dogs, cats, ferrets, as well as other wildlife species. Heartworm disease can cause heart failure, severe lung disease, other organ damage, and ultimately death. It is caused by a parasitic worm called, Dirofilaria immitis, or heartworm. The parasite is spread through the bite of an infected mosquito. Heartworm disease is deadly, but the treatment for it is also life-threatening. The best treatment for heartworm disease is prevention.

Dogs are ideal definitive hosts or organisms that support the maturation and reproduction of a parasite for heartworms. Cats are not as susceptible to a heartworm infection as dogs, as they are considered an atypical host, but it is still possible. Cats will carry a much smaller worm burden or number of worms found in an infected animal; the worms will mature to a shorter length and have a shorter lifespan in comparison to dogs. Each lifecycle of heartworm struggles to survive within a cat but occasionally can. Heartworm typically goes undiagnosed in cats because of this. Ferrets are like dogs in their susceptibility to infection but mimic cats in their symptoms and worm burden. Many wildlife species, such as coyotes, wolves, foxes, and occasionally humans, can be infected with heartworm disease.

Heartworm disease is not contagious. Heartworms are spread by an infected mosquito biting an animal, then continuing the cycle between the infected animal and the mosquito. When the mosquito bites the animal, it passes infective microfilariae, or heartworm larvae, onto the animal’s skin before entering through the bite wound. Heartworms live in the heart, lungs, and associated blood vessels of these organs. It takes approximately 6 to 7 months for microfilariae to mature into adult heartworms. The heartworms then reproduce and release more microfilariae into the bloodstream, completing the lifecycle. A heartworm’s lifespan in a dog is approximately 5 to 7 years, while only 2 to 4 years in cats.

The severity of symptoms is associated with the worm burden and how long the pet has been infected. Pet that have low worm burdens, are relatively inactive, or are recently infected may be asymptomatic. There are four stages of heartworm disease, with 1 being mild to no symptoms and 4, also called Caval Syndrome, being the most severe. Cats suffer from a disease called HARD, Heartworm Associated Respiratory Disease, which occurs when immature heartworms suddenly die within the heart and lungs causing a potentially deadly inflammatory response. Symptoms of heartworm disease are lack of appetite, coughing, activity intolerance, lethargy, difficulty breathing, advanced heart failure symptoms, and death. Diagnostics will often reveal lung and heart changes, as well as liver and kidney damage. Symptoms can vary widely between species.

Testing for heartworm disease is recommended to begin at six months of age and then yearly after that. Dogs can be effectively tested using an antigen test. This test is to reveal any antigens, or proteins, released by adult female heartworms. Antigen tests are generally ineffective in cats because it is uncommon for adult heartworms to be present, particularly female heartworms, which is required for an accurate result. The other blood test that can be used is an antibody test, which tests for the pet’s immune response to circulating microfilaria. This test is often ineffective as well because microfilaria struggles to survive within a cat. The most accurate tests in cats are radiographs and an echocardiogram.

Heartworm prevention can be started at the pet’s first vaccine appointment or at any time before six months of age. Preventative cannot be given to an animal over six months of age because the medication can cause sudden death in adult heartworms, which will cause a severe inflammatory response and possibly death in the pet. Preventative should be given once monthly, year-round. Many preventatives, such as HEARTGARD PLUS and INTERCEPTOR PLUS, protect against heartworm and intestinal parasites, while others, such as HEARTGARD, only protect against heartworm. NEXGARD PLUS protects against heartworms, intestinal parasites, fleas, and ticks. There is a preventative to fit each owner’s budget and pet’s lifestyle.

It is a common misconception among pet owners who do not live in coastal regions that their pets are not at risk for heartworm disease. Heartworm disease has been found in all 50 states, and the number of cases is growing yearly. Treatment for heartworm disease is costly, difficult to endure for the pet, and often deadly. The best treatment for heartworm disease is to provide year-round prevention to each of your pets. Do not wait until it is too late!

Call 775-738-6116 to schedule an appointment for a heartworm test and to find out what preventative is right for your pet.