Does My Dog Have Heartworm? Signs, Treatment, Prevention

Heartworm in dogs is a terrible, but preventable disease. Learn more about the signs, causes, and treatments of heartworm in dogs to protect your pet.

Brittany Leitner

Updated December 16, 2022 • Published June 25, 2021

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Does My Dog Have Heartworm? Signs, Treatment, Prevention

For most of my life, I was hoping the term “heartworm” was just a cleverly coined term that referred to anything else but an actual parasitic worm squirming its way into your pet’s organs. Unfortunately, the latter is true. 

Heartworms in dogs are caused by parasitic worms that make their way into your pet’s flesh via a mosquito bite and is a serious disease that can cause health complications if left untreated. Luckily, there are ways to cure heartworm if it’s found at your vet’s office. Here is everything you need to know if you suspect your dog might have heartworm and how you can recognize the signs so you can take action faster if it’s ever discovered. Catherine Lenox, DVM, DACVN and regulatory veterinary manager at Royal Canin explains what you need to know: 

What is heartworm in dogs?

To put it simply, heartworm disease “is caused by a worm that can live in the blood vessels, heart, and lungs of cats and dogs,” explains Dr. Lenox. Although it can be found in both dogs and cats, it manifests differently between the two species. “The number of worms present in the dog can get very high,” says Dr. Lenox. Dogs may also not show signs of heartworm as much as cats do, making it more difficult to catch and diagnose. 

 How does a dog get heartworm?

 “Dogs get heartworm infections from mosquito bites. The mosquito transfers the infection from one dog to another,” says Dr. Lenox. 

Is heartworm in dogs contagious?

Luckily, your dog cannot catch heartworm at the dog park from other dogs, but it can catch it from mosquitos present at the park itself. So you don’t need to worry about your dog catching it at any other space where multiple dogs are present, like doggy daycare or the groomers. 

“Heartworm disease is more common in dogs living in hot areas, especially those near bodies of water that allow the mosquito population to grow,” explains Dr. Lenox. “However, it’s a common misconception that dogs living in different parts of the U.S., especially colder areas, can be off of preventative [medications] for certain parts of the year. All 50 states had pets contract heartworm disease in 2019, so even though heartworm disease is more common in certain areas, it’s helpful to keep your dog on heartworm preventative year-round regardless of where you live,” she says. 

Signs your dog has heartworm

As mentioned previously, dogs are less likely to show signs/symptoms of heartworm, so it’s important to get them on preventative medicine and screened at every vet appointment. But, if your dog does show signs, they may include:

  • Coughing

  • A reluctance or inability to exercise

  • Fatigue

  • Decreased appetite

  • Weight loss

How heartworm in dogs affects life expectancy

Heartworm is a progressive disease, so it will be more dangerous if left untreated. “If the disease is caught on routine testing, and there are no signs at the time of detection, it may be possible to treat the disease,” says Dr. Lenox. “However, some dogs and many cats may have lifelong breathing or heart difficulties.”

How to diagnose heartworm in dogs

Vets use blood tests to test for heartworm. The only way to truly diagnose the disease is at a vet’s office. 

How to treat heartworm in dogs

It’s important to know that heartworm is preventable, so talk to your vet about getting your dog on prevention medicine as soon as possible. Your vet can also give an injection to help kill heartworm already present in the dog. Other helpful products to help with heartworm in dogs include:

  • Collars: Wearable collars won’t prevent heartworm but it will keep other bugs, like fleas and ticks away from your pet. 

  • All natural drops: There are some homeopathic ways to curb heartworm available on the market, but make sure to talk to your vet and see if they recommend this option.

  • Lightweight clothing: Covering up your dog may help reduce the risk of mosquito bites, but during the summer, this might not be the best option for your pup who’s already covered in fur.

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