Heartworms are caused by the parasite Dirofilaria immitis, and affect cats, dogs, and other pets, like ferrets. Heartworms are transmitted to pets when they are bitten by an infected mosquito. The larvae move through the bloodstream to the pet’s heart and lungs, where the larvae mature into adult heartworms, which can grow up to 14 inches long in the heart chambers. An infected pet may have difficulty breathing or lack energy, and heart failure can result in severe cases. Protect your pet from heartworms by following these six tips.

#1: Use heartworm prevention year-round

In some parts of the country, including California, heartworms are endemic, meaning heartworm disease is a year-round problem that doesn’t disappear in colder weather. That means your dog or cat should receive a heartworm preventive year-round, whether or not they live exclusively indoors. Although only a few mosquitoes may get into your home, a single bite from an infected mosquito is all that is needed to cause heartworm disease. Year-round prevention ensures that doesn’t happen.

 #2: Have your pets tested for heartworm before giving preventives

Some heartworm preventives, if administered to an already infected dog or cat, can cause anaphylaxis, and lead to sudden death. An animal who doesn’t show signs is not necessarily uninfected. Heartworm is a progressive disease, and many cats and dogs may show only minimal signs, or none at all, in the early stages. Only if left untreated do more severe signs occur. A rapid blood test performed in our hospital can provide an immediate answer about your pet’s possible infection.

A heartworm test is recommended if your dog or cat is not receiving year-round heartworm preventive, or if administration has had breaks or delays. New household pets with an unknown heartworm prevention history should also be tested, as should puppies and kittens more than 6 months of age. Testing earlier isn’t useful, because the worms take approximately six months to develop to a point where the test recognizes them. Additionally, resistant heartworm strains have been identified in the Mississippi River Delta. If you and your pets have traveled to this area during the past year, talk to us about the necessity of heartworm testing, including for pets on a preventive.  

#3: Maintain a mosquito-free environment

Since the only way heartworm disease can be transmitted is through mosquitoes, eradicating these pesky insects provides a second protection layer for your dog and cat. Removing standing water from your yard, keeping pets away from slow moving streams or ponds where mosquitoes breed and bite, and using mosquito netting or pet-safe repellents will not only help protect against heartworm disease, but also against other mosquito-transmitted diseases and the itchy discomfort from bites.

#4: Choose a heartworm preventive that makes compliance easy

Multiple, safe, and effective heartworm prevention formulations are available for your pet. Does a monthly chewable fit with your busy schedule? Would a topical medication release you from the horror of pilling your cat? Why don’t you visit us every six months for a heartworm preventive injection? Keeping your pet protected requires diligence to keep them on a medication schedule, so choose a system that works for you both.

 #5: Don’t forget the cat

Cats get heartworm disease, too, but unlike dogs, infected cats are more likely to demonstrate respiratory disease signs. For reasons not yet entirely understood, the heartworm larvae that live in the circulatory system typically cause disease in cats, rather than the adult worms that invade the heart. Cats in our area should receive year-round heartworm preventive, but be aware that not all heartworm preventives are safe for cats. Talk to our Colony Veterinary Hospital team to ensure you’re using an appropriate formulation for your cat and, as with dogs, test your cat for heartworm infection before starting any medication.

#6: Discuss treatment options if your pet tests heartworm positive

Thinking about adopting a heartworm-positive pet? Surprised that your pet’s current test was positive? Heartworm disease can usually be treated, although the process is lengthy and not easy on your pet. Success is dependent on the number of worms living in the heart, the worms’ development stage, and whether the pet is already showing signs. Several diagnostics, such as X-rays, are generally needed before starting treatment to determine the course of therapy. Usually, treatment for your pet requires a few weeks of different medications followed by one month of strict indoor rest. In more advanced cases, open-heart surgery may be required to physically remove large numbers of worms. In these situations, recovery can be prolonged.

During your next wellness visit to Colony Veterinary Hospital, we will be happy to discuss the heartworm preventive products we carry that help you keep your furry family members safe.