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heartworm disease in dogs and cats
Heartworm is a life-threatening blood-borne parasite. Without prevention, this disease can sicken and kill pets.
Here’s how to spot the symptoms and what to do to help prevent and treat heartworms in dogs and cats.
Early clinical signs of heartworm
- Reluctance to exercise
- Decreased appetite
- Weight loss
Emergency clinical signs of heartworm
- Persistent fatigue
- Persistent coughing
- Sudden labored breathing
- Fainting
- Pale gums from anemia
Treating heartworm in dogs and cats
Treatment for pets that already have heartworm has improved tremendously over the last 30 years, but it’s still expensive and difficult on the pet. Prevention is a far safer, more effective, and less expensive option than treating your pet after they’ve become infected.
- Oral or injected medications
- Advanced cases need additional care
- Strictly limited activity during treatment
Help prevent heartworm
Heartworm prevention is the standard and recommended way to deal with heartworms. Prevention is safe, easy, and far less expensive than treating a pet that’s already infected with heartworms. Keep your pet on heartworm prevention year-round.
- Consult your veterinary team for the best prevention for your pet
- Parasite control that helps prevent heartworm (and other worms) year-round
All about heartworm in the United States
Heartworm is a potential pet health threat in all 50 states. Dogs and cats are equally susceptible, although it's more difficult to diagnose in cats and is more commonly seen in dogs.
Heartworm and mosquito bites
Heartworm, or Dirofilaria immitis, is a parasitic worm that lives and grows within the arteries of the lungs and the heart. An untreated infestation can cause long-term organ damage and death.
Heartworm disease is life-threatening. Heartworms cause inflammation and damage to the vessel walls. The increased debris of clots and worms themselves can actively block blood flow and damage the heart and lungs.
Pets catch heartworm from the bite of a contagious mosquito. A mosquito that picks up heartworm larvae, or microfilaria, from an animal with heartworm can then spread larvae to new hosts with each bite.
Once inside the bloodstream, heartworms take about six months to mature into their adult form. Mature worms look like cooked rice noodles or angel hair pasta and can be anywhere from five to 12 inches long. Each one can release millions of new microfilaria into your pet’s bloodstream.
Even a small heartworm infestation can damage your pet’s heart. A bigger infestation — which can be hundreds of worms — can be fatal.
Many kinds of regular parasite prevention can also help protect your pet against heartworm (and other kinds of worms). Ask your veterinary team what we recommend for your unique pet!
How can I tell if my pet has heartworm?
Because heartworm larvae need about six months to mature in the bloodstream, active heartworm disease is typically only seen in pets over six months old. Infected puppies and kittens seldom show symptoms until heartworms are in their mature form.
Dogs are not the only hosts for heartworm. Cats may also suffer heart damage and develop a syndrome called heartworm associated respiratory disease (HARD) after being infected. Cats don’t typically get the large infections that dogs do, so their symptoms may be more subtle. Any change in health such as decreased energy or vomiting may be an indication of heartworm infection in cats.
Quick veterinary action can make a big difference in health outcomes for a heartworm infestation. If you suspect your pet has heartworm, please see your veterinary team ASAP. And if you do NOT suspect heartworm in your pet, make sure they are on prevention NOW.
Coughing and trouble breathing:
Heartworm often causes congestion in the lungs. Your pet may wheeze, have trouble breathing, or develop a distinctive low, dry cough.
Weakness and lethargy:
Pets with heartworm may not be getting enough body fuel or oxygen. This can lead to reduced stamina and panting, fainting, or confusion after exercise.
Reduced appetite or weight loss:
Pets that don’t feel well may eat less than usual. In general, it’s always worth investigating if a previously happy eater is suddenly refusing their meals.
Humans and heartworm
Heartworm in humans is extremely rare but possible. About two to three cases are reported each year.
Don’t let heartworm go untreated!
An active heartworm infestation needs quick veterinary care. Delaying treatment can lead to severe organ damage and congestive heart failure, which can be fatal.
If your pet has a chronic cough, lethargy, or weight loss, please see your vet.
If your pet isn’t already on a preventive for heartworm, get them started NOW.
Can I treat heartworm at home without a vet?
Pets with active heartworm infestations need veterinary care as soon as possible. Your vet will run blood tests and take chest X-rays to help confirm your dog’s infection and determine the extent of the damage. Then they’ll establish a course of treatment designed to help your pet.
Treatment for heartworm depends on how advanced the infection has become. In some cases, pets may have some damage that can't be reversed.
Pets with less advanced cases of heartworm
Pets with less advanced cases of heartworm are treated with multiple rounds of specific deworming medications plus an antibiotic.
Pets undergoing this treatment often need to be kept very calm and quiet to avoid causing complications with their heart. Follow all veterinary instructions carefully to help your pet as the medications work to fight off the parasite.
Pets with more advanced cases of heartworm
Pets with advanced heartworm disease may have long-term organ damage. Even after successful heartworm treatment, these pets often need lifelong support for chronic heart disease and other concerns.
To avoid having to treat your pet for heartworm, start them on heartworm prevention NOW.
Preventing heartworm infection in cats and dogs
Ask your veterinary team about year-round veterinary parasite control that includes protection against heartworm! Many kinds of parasite prevention can help guard against different problems, including fleas, ticks, heartworm, and even intestinal worms like tapeworm, roundworm, and more.
Heartworm prevention can be dangerous if a pet takes it when they have an active heartworm infestation. It’s very important that you see your veterinarian for proper testing before we prescribe medication for your pet.
Heartworm prevention needs to be taken on a strict schedule to be effective. Just to be on the safe side, always reach out to your veterinary team if your pet has any symptoms that worry you — even if your pet is on regular parasite control.
An Optimum Wellness Plan is a smart way to prevent pests
Our Optimum Wellness Plans® are affordable yearlong packages of essential preventive care. They're designed for different needs, ages, and lifestyles, and most include a yearly heartworm test that can also detect a number of tick-borne diseases.
It’s a simple way to tell if your pet has been exposed to any of these potentially dangerous diseases. Talk to your Banfield vet to find out what package is best for your pup or cat.
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