With heartworm disease prevention, what you don’t know can hurt your pet. Heartworm disease is a serious and potentially life-threatening condition that can damage your pet’s heart, lungs, and other organs. Your knowledge about the disease and effective prevention is essential to protecting your pet. Read our Tamberly Animal Hospital team’s guide to safeguarding your pet from heartworm disease.
The heartworm life cycle
When a mosquito infected with Dirofilaria immitis bites your pet, they can transmit heartworm disease, which infects a variety of mammals. Learn about the heartworm’s complex life cycle:
- Mosquito bites infected host — The heartworm life cycle begins when a mosquito bites an infected host (e.g., domestic dogs, wolves, foxes, raccoons), ingesting the microfilariae (i.e., immature worms).
- Microfilariae develop within the infected mosquito — After the microfilariae develop for 10 to 30 days within an infected mosquito’s body, they become infective larvae—and a serious risk to pets—including dogs, cats, and ferrets.
- Infected mosquito transmits the parasites into a new host — The infected mosquito transmits the infective larvae to a new host when they bite another animal, who then becomes a host for other mosquitos. As the infected mosquito feeds, immature heartworms migrate into your pet, traveling to the blood vessels surrounding their heart and lungs.
- Immature heartworms mature — Without routine heartworm prevention, these immature heartworms create serious damage as they travel through your pet’s body to reach their heart and adjacent blood vessels. Here, heartworms mature into adults—growing up to 12 inches in length—mating, and reproducing microfilariae within 6 to 7 months.
Heartworms damage your pet’s cardiovascular system
Adult heartworms clog an infected pet’s heart and major blood vessels leading from the heart, including the pulmonary artery. These parasites also interfere with the function of the valves within the heart. When the main blood vessels are clogged, the blood supply to other organs of the body is reduced, particularly blood flow to the lungs, liver, and kidneys. Decreased blood flow and decreased oxygen delivery can cause these organs to malfunction.
Heartworms affect cats differently than dogs
Feline heartworm disease presents differently than the canine type. Unlike dogs, cats are atypical heartworm hosts, and most worms in cats do not survive to the adult stage. As a result, infected cats typically have very few adult heartworms—usually one to three. However, the immature worms inside a cat can cause serious damage by causing the lung condition heartworm associated respiratory disease (HARD). When the parasites die off, they can cause an inflammatory response in the smaller lung blood vessels, the airways, and the lung tissue, which can lead to severe breathing difficulties and sometimes sudden death.
Heartworm signs are not always obvious in pets
Most infected pets are asymptomatic until the worms have reached maturity inside the heart and major lung vessels. Dogs’ heartworm disease signs include:
- Exercise intolerance
- Decreased appetite
- Weight loss
- Abdominal fluid accumulation
Cats with heartworm disease typically develop HARD. These signs include:
- Asthma-like attacks
- Periodic vomiting
- Weight loss
- Difficulty walking
- Abdominal fluid accumulation
If your cat contracts heartworm disease, they may not show signs until the worms have clogged their blood vessels. Unfortunately, one of the first feline heartworm disease signs can be sudden collapse or death.
All pets require regular heartworm tests
Even if your pet takes year-round preventives, their veterinarian should test them annually for heartworm infection. You leave your pet open to infection if you inadvertently forget to give them one dose of their monthly medication. Regular heartworm tests enable your veterinarian to detect infection early, giving your pet the best chance for a full recovery. Your veterinarian can perform two main tests for detecting heartworm infection:
- Testing for adult worms — This blood test is designed to detect a protein (i.e., antigen) on adult female heartworms, or heartworm antibodies’ presence.
- Testing for microfilariae — The Amercian Heartworm Society also recommends testing their blood to check for microscopic larvae (i.e., microfilariae), which are more commonly found in dogs, rather than in cats.
Heartworm treatment is costly and complex for pets
Heartworm treatment—only available for dogs—is a costly multistep process that takes several months and involves a series of deep intramuscular injections that kill off circulating adult heartworms. Because no heartworm treatment is available for cats, prevention is the only means of protecting your feline friend from this life-threatening disease.
Heartworm prevention is necessary year-round
Year-round prevention is the only way to keep your pet safe from heartworm disease. Fortunately, many heartworm preventive varieties are available, including topical, oral, and injectable forms. Your veterinarian can customize a prevention program for your pet.
With heartworm disease prevention, what you don’t know can hurt your pet. Learn all you can about heartworm disease and prevention to help keep your pet from contracting this deadly parasitic infection. Contact our Tamberly Animal Hospital team to perform your pet’s heartworm testing and establish their unique parasite prevention plan.