According to the American Heartworm Society, virtually 100 percent of dogs and up to 90 percent of cats exposed to mosquitoes carrying the infective larvae will become heartworm positive. Fortunately, heartworm prevention can help you protect your pet from the damage heartworms can do.

Treatment of established heartworm disease is not only expensive but also very dangerous to the animal. In cats, the risk of complications is high once heartworm disease is detected. The best solution is heartworm prevention, which is as simple as flea control if you follow the right steps. A monthly dose of heartworm preventive kills the larvae before they can take root in your pet’s heart and lungs.

Here is the truth behind some of the myths surrounding heartworm and why you need to keep your pets safe from this damaging condition:

Fact #1: Pets need heartworm prevention all year round

Although mosquitoes are more active in summer, pets who live in North Carolina can contract heartworm all year long. This risk is higher if you travel with your pet. All it takes is one bite from an infected mosquito. Because of this, the American Heartworm Society (AHS) recommends that pets should receive heartworm preventives every month — even if it’s snowing outside and even if you have an indoor pet.

Fact #2: Cats are not safe from heartworms

Cats are slightly less likely to get heartworms than dogs, but they’re not immune. Between 65 and 90 percent of cats bitten by an infected mosquito will develop heartworm. Many pet owners with indoor-only cats think they don’t need to give monthly heartworm prevention treatment. However, mosquitoes do get inside, and the risk is not zero.

Fact #3: Treatment is difficult and dangerous

Treatment of heartworms requires a series of injections containing an organic arsenical compound. That’s right, arsenic. Treatment can cause pulmonary thromboembolism (blood clots in the lungs) and sometimes sudden death. Treatment of heartworm in dogs costs more than $1,000. Without treatment, however, an infected pet will eventually die of heart problems or kidney or liver failure. There’s no approved treatment for heartworm in cats.

Fact #4: There’s no vaccine against heartworms

Heartworms are a parasite. No vaccination can prevent them. Your pets need to take a monthly heartworm prevention product throughout their entire lives. Stopping or skipping dosages leaves your pet at risk of infection. Most spot-on flea control treatments protect against ticks and fleas. Those products don’t offer protection against heartworm, so if you use topical flea control or flea collars, you need to buy an additional chewable tablet or pill to ensure your pet is protected.

Fact #5: Heartworm is not contagious

If your pet is heartworm positive, you don’t need to isolate him or keep him away from your kids or other pets. A mosquito biting the infected pet will not transmit the disease to humans or other animals. While it might be distressing to find out your pet has heartworm, there’s no need to give him up or keep him away from the family.

Fact #6: Many pets with heartworm have no symptoms

There are four stages of heartworm disease:

  • Stage one: pets have no symptoms at all. A blood test can detect heartworm larvae.
  • Stage two: animals have mild symptoms such as tiring easily or an occasional cough.
  • Stage three: the infection is widespread. Your pet will experience trouble breathing and persistent coughing.
  • Stage four: your pet will show signs of serious illness, including loss of interest in exercise and coughing up blood.

Just because you don’t see any issues doesn’t mean your pet is not infected and in need of emergency treatment.

The most important thing to know is that heartworm prevention is the best course of action. Prevention is not only cheaper than treating the condition, but your pet will live a longer, healthier, happier life if you keep heartworms away.

For more information, read Dr. Simone Lemieux’s article on Heartworm in Dogs and Cats.