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Why Should I Care About Heartworm Disease?

Why Should I Care About Heartworm Disease?

               April is Heartworm Awareness Month.  Let’s learn some myths and facts about this potentially fatal illness and why you should protect your pet year-round.

               First of all, what is heartworm disease?  Heartworms are blood parasites that start out as small, microscopic larvae in the bloodstream. Heartworm disease is spread by mosquitos. A mosquito bites an infected animal and sucks up the larvae (called microfilaria) as it feeds.  Dogs aren’t the only animals affected—cats and ferrets can also be infected and wild animals like fox and coyotes are carriers and act as reservoirs for the disease. Microfilariae mature inside the mosquito’s gut in about two weeks. Mature larvae are injected into a new host when the mosquito bites another animal to feed. These larvae grow into adult worms up to a foot long that live within the heart and large blood vessels in the heart and lungs. It takes about seven months for the larvae to grow into adult worms and they can live inside the heart for many years causing serious damage.

               Mosquito season in Pennsylvania tends to be seasonal as opposed to, say, Florida,  But, with warmer winters, mosquitos may be present periodically throughout the year.  Travel with pets, visiting beaches, lakes, and campgrounds can mean increased exposure to mosquitos. Pennsylvania, Maryland and surrounding states like New Jersey and Delaware have a similar incidence of about 1 in 200 dogs being infected with heartworm disease.  In 2022, York County had 175 heartworm positive dogs and there have been 30 dogs diagnosed so far in 2023.  The incidence may be even higher as many cases go unreported.  By comparison, in North Carolina, one in fifty dogs are infected and there were a whopping 14, 673 cases last year.

               Indoor pets are not exempt from exposure.  Surely, we have all seen mosquitos in our homes. Cats and ferrets can also be infected with heartworms, and, there is no treatment available.  They can develop severe respiratory disease which can impact quality of life and may cause sudden death. Early in the course of disease, there may be no symptoms, but, as worms mature and damage the heart and lungs, dogs may develop a cough, exercise intolerance and weight loss.  Over time, congestive heart failure may develop.             

               So, what can you do to protect your pet from heartworms? Many effective heartworm preventatives exist for dogs and cats. These drugs do not prevent exposure, but they work by killing larvae before they mature.  Larvae mature in as little as 51 days into a stage not killed by preventatives.  Monthly chewable or topical products are great, but missed doses can lead to breakthrough and heartworm infection.  An injectable product called Proheart 12 (dogs only) provides a continuous full year of heartworm protection with a single injection under the skin. Periodic blood tests are also needed to ensure products are working to protect your pet.

               Heartworm disease is easy to prevent, but difficult to treat once infected.  There is no approved treatment for cats who often develop severe lung disease. Cats are not the normal host for heartworms, so even one or two adult worms do significant damage to the cat’s heart and lungs.  Dogs can be treated, but the treatment is harsh, lengthy, and costly.  Dogs must start antibiotic and steroid treatment then undergo a series of deep intramuscular injections to kill the worms.  While this treatment is often successful, it does have risks including pain, allergic reaction and even death, especially in dogs with more advanced disease.  The drugs used to prevent heartworm disease are very safe and are not poisons unlike melarsomine, the treatment for heartworm disease which is, in fact, an arsenic-like compound.

               Please make sure your pets are protected against heartworm disease. Talk to our staff and vets about which preventative is right for your pet.

               This blog brought to you by the Patton Veterinary Hospital serving Red Lion, York and the surrounding communities.