Heartworm disease, a serious illness that affects dogs, cats, and other animals, is transmitted by mosquitoes that have picked up larval worms from infected dogs. When a mosquito carrying heartworm larvae bites another dog or cat, the worms are injected into that animal’s body, where they begin to make their way to the heart, lungs, and surrounding vessels. The worms stay there as they mature, a process that takes about six months. Once mature, the foot-long worms begin to multiply and accumulate in the heart and blood vessels, clogging important parts of the animal’s body and causing many problems:

  • Inflammation of the blood vessels and surrounding lung tissue compromises the respiratory system
  • Obstruction of blood flow interferes with blood circulation through the heart and lungs
  • Blood clots or pieces of dead worms can lodge in vessels of the lungs and cut off blood supply

Cats can also contract heartworms, but, because they are not natural hosts, heartworms cannot reproduce within them and the disease manifests differently than it does in dogs. When heartworm larvae are passed to a cat from a carrier mosquito, the worms may not even live to maturity, but they can still cause significant inflammation and tissue damage with lifelong consequences for the cat.

Heartworm disease can be acquired at any time

Since mosquitoes are most active in the warm summer months, many people assume that they are not a threat during the winter months.

Mosquitoes can emerge whenever temperatures reach 50 degrees or higher. Since the average daily temperature is above 50 degrees through most of the year, mosquitoes can be found in Tennessee almost all year long. This means that heartworm disease is a year-round threat.

Heartworm disease is deadly

Heartworm disease causes significant damage to the heart and lungs. Inflammation and tissue damage can cause the following symptoms in dogs:

  • Coughing
  • Lethargy
  • Anorexia
  • Weight loss

Unfortunately, dogs often do not show clinical signs until a large population of worms are present and the disease is quite advanced. As heartworms multiply within the body, they obstruct blood flow through vital structures. Blood clots or the worms themselves can lodge within vessels of the lungs, causing pulmonary embolism. Both of these complications are life-threatening. If the disease is not treated, worms will continue to accumulate and will eventually cause death.

Since cats only harbor a few worms, they often do not display symptoms at all. However, the inflammation associated with the presence of the worms can become severe enough to cause dangerous respiratory compromise and even sudden death.

Treatment is risky and costly

There is a treatment for heartworm disease in dogs, however the course of therapy is lengthy, costly, and risky. The medication used kills the adult worms. As worms die, the risk of pulmonary embolism increases, as disintegrating worms can block blood flow to the lungs. During the months of treatment, sudden death is a concern as the body breaks down the dead worms.

Since treatment is a risky endeavor, it is administered over a period of months to give the body time to break down and resorb the dying worms. Medications are also administered to decrease inflammation, kill circulating immature worms, and kill bacteria associated with the worms’ presence.

There is no cure for feline heartworm disease because the medication used to kill heartworms in dogs cannot be used in cats. Treatment in cats is aimed at reducing the inflammation caused by the worms and managing symptoms until the worms die on their own.

As is the case with many diseases, prevention is the best treatment. By giving your pet a monthly preventive, you are ensuring that heartworm disease will never be a concern. The preventives available from your veterinarian are easy to administer—most are flavored, and dogs and cats gobble them up like a treat.

Most heartworm products prevent more than just heartworm disease

Many of the commonly used heartworm preventive products provide protection from other parasites as well. Most protect against intestinal worms, such as roundworms, hookworms, and even whipworms. Picked up from the environment, these gastrointestinal pests can cause vomiting, diarrhea, and even blood loss.

Some products may even provide flea and tick prevention. Fleas and ticks are also a year-round threat here in Tennessee, and both parasites can transmit dangerous disease to both you and your pet.

Does your pet receive a regular heartworm preventive medication? Call us if you need a refill. Never used heartworm prevention before? Missed a few doses? A simple blood test can be performed in our office to confirm your pet is heartworm-free, then we will recommend the best preventive for her lifestyle.