Although more than a million pets in the United States have heartworms, this serious and potentially fatal disease that mosquitoes carry is preventable, according to the American Heartworm Society (AHS). Since 1974, this organization has been educating the public about heartworms and furthering scientific research to prevent, diagnose, and treat heartworm disease.

The news that’s not so great is that the battle against heartworm disease is more challenging in central-west Florida than in many other places. Mosquitoes, which play an essential role in the heartworm life cycle, are most active here from May through October. However, these irritating insects can lay their eggs year-round in St. Petersburg’s warm, humid climate. 

Fortunately, our Skyway Animal Hospital team has a full arsenal of preventives with which we can arm your pet against heartworm disease. During your pet’s annual wellness checkup, our team can determine which preventive would be most effective for your furry pal. In the meantime, consider this important information about heartworm disease.

Facts about heartworm disease in pets

Adult female heartworms living in an infected dog or cat produce microfilaria, microscopic baby worms that circulate in the bloodstream. When a mosquito feeds on an infected animal, the insect ingests these baby worms, which develop into infective larvae within the mosquito over 10 to 14 days. When the infected mosquito bites another pet, the insect deposits larvae that enter the new host through the bite wound. 

Larvae inside the host develop into sexually mature adult heartworms in about 6 months. These adult parasites can live 5 to 7 years in dogs and 2 or 3 years in cats, so an infected pet can acquire more heartworms each year.

These foot-long, spaghetti-like worms live in a dog’s or cat’s heart, lungs, and blood vessels, causing severe lung disease, heart failure, and damage to other organs in the body. Heartworm disease affects dogs, cats, ferrets, and wild mammals such as wolves, coyotes, foxes, and sea lions. Heartworm disease rarely affects people. 

Heartworm disease in dogs

The dog is a natural heartworm host, and these parasites can complete their entire life cycle—maturing, mating, and producing offspring—inside your dog. Dogs with untreated heartworm disease have been known to harbor several hundred worms in their bodies. Heartworm disease causes lasting damage to the heart, lungs, and arteries, and can affect a dog’s health and quality of life long after the parasites have been eradicated. For this reason, prevention is the best option, and when treatment is necessary, it should begin as early as possible in the disease process.

Heartworm disease in cats

Heartworm disease often goes undiagnosed in cats, who are atypical heartworm hosts. Most worms in cats do not survive long enough to mature, so cats with adult heartworms typically have just one to three worms, and many cats with heartworms have only larvae. However, immature worms can still damage a cat’s heart through heartworm associated respiratory disease (HARD). Unfortunately, the medication veterinarians use to treat heartworm infections in dogs cannot be used in cats. So, prevention is the only way to protect your whiskered pal from heartworm disease’s damage.

Heartworm prevention in pets

While you may think your indoor cat or dog is safe from mosquito bites, think again. Living indoors doesn’t eliminate a pet’s heartworm disease risk—indoor living only decreases their risk. Mosquitoes can sneak into your home when you open a door, and if your pet gets one infected female mosquito’s bite, they can contract heartworm disease. All cats and dogs need year-round protection against heartworm disease. Preventive types include:

  • Monthly chewable pills
  • Topical medications
  • Injectable medication given every 12 months to dogs or every 6 months to cats

Heartworm diagnosis in pets

Diagnosis can be challenging. Symptoms commonly seen during a cat’s first stage of heartworm disease can mimic feline asthma or allergic bronchitis. Dogs and cats with early heartworm disease have breathing problems and may cough, have little appetite, lose weight, and be lethargic. Cats may also gag or vomit. 

In dogs, signs don’t appear until heartworms start living in the pet’s lungs and heart. Diagnosis includes blood tests, heart ultrasound, and chest X-rays. For cats, diagnosis involves a complete blood count (CBC) and blood chemistry profile, chest X-rays, other tests, and sometimes ultrasound. 

Heartworm treatment in pets

Heartworm treatment for dogs is 98% effective but involves a series of melarsomine injections, the only drug the U.S. Food and Drug Administration (FDA) has approved for this purpose. Six months after the injection series is complete, our veterinarian performs a follow-up test to ensure your dog’s heartworms have been eradicated. 

The outlook is not as good for cats with heartworm disease. Treatment is not available for them because their systems cannot tolerate the strong medication used to treat dogs. However, cats sometimes throw off the infection on their own.

To learn more about heartworm disease or schedule your pet’s annual wellness appointment, contact our Skyway Animal Hospital team.