Levamisole in Dogs

Levamisole is a drug with both human and veterinary uses. It is sold commercially in two forms, as a phosphate and as a hydrochloride. In humans, it is generally used as immune system stimulant during treatment for cancer, while in animals such as cattle and swine, it is used to kill certain parasitic worms. In dogs, it is used as it is in humans--as part of treatment for some kinds of cancer. It is also used as it is in other animals, to kill parasites, but specifically to treat infections of one parasitic worm in particular, Dirofilaria immitis.

  1. Levamisole and Dirofilaria immitis

    • In dogs, levamisole is used as a microfilaricide against Dirofilaria immitis, the parasite more commonly known as heartworm. This parasite, which can grow to be as much as 14 inches long, lives in the heart and blood vessels of dogs and cats. Larvae of this parasite are transmitted among animals by mosquitos, who pick them up from the blood stream while biting the animals. Levamisole, as a microfilaricide, attacks the larval form of this parasite that may be living in the body of the dog.

    Microfilaricide Mechanism of Action

    • Levamisole is effective against certain kinds of parasites because it stimulates the nervous system (parasympathetic and sympathetic ganglia) of the worms, while simultaneously interfering with carbohydrate metabolism, the processing of sugar from which the parasites derive their energy. As a result, the worms suffer paralysis and can then be removed from the body alive.

    Immunostimulating Mechanism of Action

    • According to Elephant Care International, a website that provides extensive, expert information on veterinary medicine, "Levamisole's mechanism of action for its immunostimulating effects are not well under­stood." It may work by restoring the function of certain T-lymphocytes, a type of immune system cell, and stimulating other cells, specifically monocytes, to better function with regard to their ability to engulf foreign, potentially harmful substances in the body.

    Adverse Effects

    • In dogs, possible negative side effects include vomiting, diarrhea, panting, shaking, agitation or other behavioral changes and lethargy. Other, more serious adverse effects may include agranulocy­tosis, dyspnea, pulmonary edema, erythroedema, ery­thema multiforme and toxic epidermal necrolysis.

    Precautions

    • Levamisole is not approved for use in lactating animals. It should be used cautiously in animals with severe debilitations, impaired kidneys or impaired livers.