What is Heartworm Disease?
Heartworm disease can be a devastating condition, frequently fatal if left untreated. The disease is caused by a microscopic parasite that is carried by infected mosquitoes. The parasites migrate through the bloodstream of your pet, eventually reaching the heart and lungs where they mature to adult “worms.”

Treatment for an infected dog is costly, and not without risk; for cats, unfortunately, there is currently no approved treatment.  However, heartworm disease can be easily prevented, for less than the cost of your favorite daily espresso drink! We recommend that all dogs be given a heartworm preventative medication year ’round: medication should be given once every 30 days, every month, for all twelve months of the year. Cats, while less susceptible to heartworm infection – they are not the parasite’s “ideal host” –  should also receive monthly preventative, especially if they spend any time at all outdoors. There are several brands and types (oral or topical) of preventative available, and most of them protect against a range of intestinal and/or external parasites in addition to protecting your pet against heartworm.¹

All dogs must be tested yearly for heartworm, prior to starting or continuing any preventative medication.² The antigen test requires just a small blood sample, and can be completed in our hospital in as little as 15 minutes. Heartworm infection in cats is harder to detect than in dogs, because cats are much less likely than dogs to have adult heartworms; the preferred method for screening cats includes the use of both an antigen and an antibody test, which detects exposure to heartworm larvae.

Dissected heart showing heartworm infestation

Is Heartworm Really a Big Deal in Nebraska?

Heartworm disease has been diagnosed in all 50 states, and risk factors are virtually impossible to predict. Multiple variables, from climate variations to the presence of wildlife carriers, cause rates of infections to vary dramatically from year to year – even within communities. Even if heartworms do not seem to be a problem locally, your community may have a greater incidence of heartworm disease than you realize – or you may travel with your pet to an area where heartworms are more common, unbeknownst to you. Another big risk factor is other infected dogs or wildlife: most mosquitoes have a range of only about 2 km, so if there is a heartworm-positive dog in your neighborhood, then 33% of the mosquitoes in the area are infective! In addition, heartworm disease is spreading to new regions of the country each year. In the southeastern Nebraska area (Douglas and Sarpy counties,) data from the year 2022 indicates that at least 358 dogs tested positive for heartworm³, according to the Companion Animal Parasite Council.  Of all positive cases in the state of Nebraska in the year 2022, 14% were in Sarpy County, and 42% were in Douglas County.

Why Does My Indoor Dog or Cat Need Heartworm Preventative?

Mosquitoes are tiny and stealthy little devils, and they can (and do) easily enter your home when you open a door or a window, or they can simply crawl in through a screen. They might also hitch a ride on you or another pet, thereby gaining access to your indoor pet. Just one bite from an infected mosquito is all it takes to transmit the heartworm parasites to your pet!

What If I Just Use a Mosquito Repellant On My Pet?

Mosquito repellent is NOT a replacement for heartworm prevention; however, a pet-safe repellant can certainly save your pet from some uncomfortable bites, and potentially minimize the chances of an infected mosquito transmitting the heartworm parasite to your pet.

If you have any questions about heartworm disease, prevention, or treatment, please feel free to contact our veterinarians at any time!

¹It is important to understand that no single product will eliminate all species of internal and external parasites, and you should consult your veterinarian to determine the best product for your pet and your household.

²Annual testing is necessary, even when dogs are on heartworm prevention year-round, to ensure that the prevention program is working. Heartworm medications are highly effective, but dogs can still become infected: if you miss just one dose of a monthly medication, or give it late, your dog could be unprotected. Even if you are vigilant in giving the monthly dose, your dog may spit out or vomit a heartworm pill when you’re not looking. Heartworm preventives are highly effective, but no medication can be considered 100% effective. If you don’t get your dog tested, you won’t know whether or not he’s infected with the parasite!

³ The CAPC estimates that their mapped data represents less than 30% of the activity in the geographic regions, so the total number of positive tests in any particular region may in fact be higher than indicated.