Heartworm Treatment Side Effects

Heartworm infections in dogs and cats have become a problem around the world. Although there are improved preventive measures, many pets still are diagnosed with heartworm each year, and they require further treatment. Dog and cats have varying side effects and rates of success with treatment.

  1. Heartworm

    • Heartworm is an infection passed to dogs and cats by mosquitoes that have bitten an animal that was infected. Mosquitoes carry heartworm larvae that enter an animal through the bite wound. Typically an animal shows no immediate signs; it takes an average of more than six months for heartworms to grow to adult size inside of a dog or cat. Heartworm can be a cause of death for a pet, but an animal can survive with the infection for an extended period of time.

    Canine Treatment

    • Although about 30 species of animals can become infected with heartworm, dogs are the pets most often seen with the condition. There are a few different drugs that can be administered. These medications are classified as adulticides and microfilaricides. Adulticides target adult heartworms, while microfilaricides kill any remaining larvae and immature heartworms. These drugs are given typically in two injections at varying intervals, depending on the severity of the infection.

    Basic Side Effects

    • The most common and side effects of heartworm treatment in dogs include: coughing (sometimes with blood), lack of appetite, fever, pain or swelling at the drug injection site, vomiting, excessive drooling, diarrhea, depression and abnormal heart rhythms. The amount and severity of side effects are directly related to how far the heartworm infection has progressed.

    Severe Side Effects

    • The severity of the infection can vary greatly from case to case. Heartworms can live in a dog for five to seven years. With a severe infestation, there is a greater chance of more complications. Animals can experience restricted blood flow in the pulmonary arteries if damage has occurred from the worms, or if the amount of dead worms simply clogs the area. This type of complication is extremely serious and could cause sudden death. It is important to restrict physical activity of any pet for four to six weeks after treatment, to prevent serious side effects. In cases of severe heartworm infestation, surgery to remove the worms could be used as a last resort.

    Felines

    • Heartworm infections are much less common in cats than in dogs. Often cats that become infected with heartworm get better on their own, without any additional help. There are currently no approved drugs to be administered to cats to aid in the killing of heartworms, due to the high risk of complications. Felines typically are given time to recuperate on their own, but can be aided by some therapies, rest and common antibiotics.