Heartworm Disease in Dogs and Cats

Mississippi, with its warm, humid summers that breed mosquitoes in droves, is heartworm territory. Mississippi veterinary clinics treat more heartworm disease cases than clinics in almost all other states. Read on to learn the facts about protecting your pet from heartworm disease.

What is heartworm disease?

Heartworms, or Dirofilaria immitis, are parasitic worms that complete their life cycle inside a canine host. Once inside a dog’s body, the heartworm larvae migrate to the heart and the blood vessels of the lungs where they mature into full-grown worms, which can be as long as 12 inches, and reproduce. The immature worms, called microfilariae, also reproduce as they mature, so the number of worms grows dangerously high and can cause a number of problems:

  • The presence of foreign organisms incites inflammation in the blood vessels and surrounding tissue.
  • The worms impede blood flow through the heart.
  • The inflammation and insufficient circulation can cause fluid build-up in the lungs.

As worms accumulate and obstruct blood flow, dogs develop congestive heart failure, which will progress to death without treatment.

How can my pet get heartworm disease?

Heartworms are transmitted by mosquitoes. When a mosquito bites a dog with heartworm disease, it ingests microscopic larvae along with the dog’s blood. The larvae are then transmitted from one dog to another when the mosquito bites another dog and passes on some larvae.

Although dogs are the intended hosts for heartworms, cats can also be affected. Mosquitoes are less likely to bite indoor cats, but these cats are still at risk from infected mosquitoes that can get into your home. Larval worms in the cat can migrate to the heart and lungs and mature to adulthood, but they cannot reproduce and multiply. However, just a few worms can cause inflammation and other clinical symptoms.

How do I know if my pet has heartworm disease?

If your dog develops heartworm disease, the worms in the heart and lungs will eventually cause these symptoms:

  • Lethargy
  • Weakness
  • Tiring more easily
  • Coughing
  • Vomiting

In cats, because the worms do not multiply, there is no obstruction of blood flow. However, the heartworms trigger inflammation that can cause severe disease, with coughing and wheezing the most likely signs. Unfortunately, some cats show no signs, but die suddenly.

Performing a blood test during your pet’s annual wellness visit is the best way to screen for heartworm disease. A heartworm test requires only a few drops of blood and can be administered quickly and easily.

How is heartworm disease treated?

Heartworm disease in dogs is treated with medications that kill the adult worms and circulating microfilariae and reduce the inflammation caused by dying and dead worms. During treatment, which typically takes several months, dogs are restricted from all activity except short leash walks. The dead, disintegrating worms can lodge in blood vessels and cause a pulmonary embolism, and the best way to prevent this potentially deadly complication is keeping dogs calm during treatment.

There are no medications that can safely be used to kill adult heartworms in cats, so treatment is aimed at reducing the inflammation and other problems caused by the worms.

How can I protect my pet from heartworm disease?

The saying, “An ounce of prevention is worth a pound of cure,” definitely applies to deadly heartworm disease. Treatment is also risky, so prevention is critical. The good news is that heartworm disease is easily prevented. Many prescription products will prevent your pet from suffering the effects of this deadly parasite. Heartworm prevention medication should be given monthly and administered year-round. Most products are flavored, so pets think they are a special treat.

If your dog or cat is not currently on a heartworm preventive, let’s get started. Our veterinary team will first run a heartworm test to be sure your pet is heartworm-free and then suggest the best preventive product.

Do you have questions about heartworm disease? Contact our office today!