Heartworm Disease in Dogs

Heartworm disease is a serious, potentially fatal condition caused by the parasitic worm Dirofilaria immitis. These worms inhabit a dog’s heart, lungs, and blood vessels, causing long‑term damage and, in severe cases, death.

Rising Incidence

According to the American Heartworm Society, heartworm cases have been increasing nationwide. The most recent incidence map from 2022 highlights elevated infection rates—especially in the southern U.S.—driven by warmer weather, low compliance with preventives, and movement of infected dogs.

How It’s Transmitted

• Infected dogs, foxes, and wolves release microscopic larvae (microfilariae) into their bloodstream.
• Mosquitoes bite these animals, ingest the larvae, and allow them to mature over 10–14 days.
• When those mosquitoes bite healthy pets, they transmit infective larvae, which develop into adults over 6 months.

Recognizing the Symptoms

Symptoms often go unnoticed in the early stages:

• Mild persistent cough
• Tiring quickly with exercise
• Reluctance to move
• Loss of appetite and weight

As the disease progresses, signs may include:

• Difficulty breathing
• Fluid buildup in the abdomen
• Collapse, pale gums, or dark urine (a sign of caval syndrome, a life-threatening blockage)

The Importance of Prevention

Prevention is vastly safer and more effective than treating an established infection:

• Monthly preventives (like ivermectin, milbemycin, moxidectin, etc.) kill early-stage larvae before they mature
• Yearly heartworm testing is vital—even pets on prevention should be tested annually
• Reducing exposure to mosquitoes—by avoiding peak mosquito hours and using repellents—also helps.

With spring and summer mosquitoes returning, now is the perfect time to remind yourself that heartworm disease is not just dangerous, it’s preventable with consistent preventive treatments, annual testing, and mosquito control.

Let us know if you’d like help choosing preventive medication or tips to reduce mosquito exposure for your pet!

Source:

What is Heartworm Disease? Available at: https: //www.heartwormsociety.org/pet-owner-resources/heartworm-basics?utm

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