How would my dog catch heartworm?

Your dog can catch heartworms through a mosquito bite. If a mosquito carrying the heartworm bites your dog, the heartworm is transmitted to your pet. The heartworm stays in your dog's muscles for about six months, developing over time. After six months, it migrates through the blood to the heart and lungs, where the adult heartworms form and cause problems.

Dr. Joanne Goodman
Evendale-Blue Ash Pet Hospital

Can dog heartworm be prevented?

Dog heartworm can definitely be prevented. You can use oral chews given every 30 days, monthly, year-round, or a heartworm-preventative injection that can last either six months or 12 months, depending on your choice.

What are the early-stage symptoms of heartworm in dogs?

Unfortunately, some dogs show no signs of heartworm, and the disease is only discovered during an annual preventative blood screening or heartworm test. Early-stage symptoms of heartworm disease can include lethargy, a persistent cough that doesn't go away, and decreased appetite leading to weight loss.

What are the middle to late-stage symptoms of heartworm?

Middle to late-stage symptoms of heartworm can include abnormal sounds when your pet is breathing, a bulging ribcage when breathing due to increased effort, difficulty breathing, an enlarged liver, and a heart murmur. The heart murmur is caused by adult heartworms living in the heart, causing blood flow to back up in the body.

What can be done to stabilize my dog's heartworm disease?

To stabilize your dog's heartworm disease, your veterinarian will first confirm the stage of the disease through blood work, checking for microfilaria (heartworm larvae), and taking x-rays of the heart and lungs. Once the stage is determined, your vet will develop a treatment plan. It's important to restrict your dog's exercise during treatment because the dying heartworms can cause clots, which can lead to sudden death. Treatment involves injections, testing, and starting your dog on heartworm prevention right away. From experience, I can say that treating dog heartworm is not a fun process. The injections can be painful, and it’s tedious trying to keep your pet restricted. After treatment, we will test them again to ensure the treatment worked and we start them on heartworm prevention right away.

When should I bring my dog to see a veterinarian for heartworm prevention?

If your dog is a rescue, bring it to the vet right away, even if the rescue organization has already tested for heartworm because they may have heartworm even if they test negative. For puppies, start them on heartworm prevention immediately. Their first heartworm test should be done at the one-year or one-and-a-half-year mark during their first annual wellness exam, as long as they haven't missed any months of heartworm prevention.

How will a veterinarian diagnose if my dog has heartworm?

Heartworm is diagnosed through blood work. The veterinarian will draw blood from your pet and send it to a lab, which will test for heartworm antigens and microfilaria. The lab will also confirm if the test is truly positive.

Why is early detection and diagnosis of heartworm so important?

Early detection and diagnosis of heartworm are crucial because it minimizes the damage done to the heart and lungs. Catching heartworm in the early stages can prevent sudden death and other complications from late-stage heartworm disease.

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