Canine Leishmaniasis

Worldwide about 12 million people have leishmaniasis and about 350 million are at risk of acquiring it. Leishmaniasis is caused by numerous species of protozoan parasites in the genus Leishmania.

Two Forms of Leishmaniasis

Leishmaniasis occurs in two principal clinical forms, known as cutaneous leishmaniasis and visceral leishmaniasis. While a given species of Leishmania typically produces one or the other clinical form, some can produce both.

Cutaneous Leishmaniasis

In cutaneous leishmaniasis, multiple skin lesions can develop at sites of multiple bites. Lesions can remain nodular or can develop into ulcers that discharge necrotic material. New areas of the body become involved by extension of the existing lesions or spreading of the parasite through blood and lymph. Cutaneous leishmaniasis can be transmitted from animals to humans.

Visceral Leishmaniasis

Visceral leishmaniasis is also known as kala-azar ("black fever") and dumdum fever. This chronic from of leishmaniasis is usually fatal, if untreated. Visceral leishmaniasis can be transmitted to animals and humans via sand fly bite.

The tiny elongated protozoa eneter the body from the saliva of a sand fly (Phlebotomus sp.) bite. The parasites live inside the host's white blood cells and some other target cells and tissues.

Veterinary forms of leishmaniasis are canine leishmaniasis and feline leishmaniasis. Both domestic dogs and cats are susceptible to cutaneous leishmaniasis.

Signs of Leishmaniasis

The signs vary, from a single, hard nodule in the skin to severe internal damage, particularly to the liver (which can be fatal). Symptoms of leishmaniasis include skin lesions, nosebleeds, swollen lymph nodes, weight loss, seizures, swollen limbs and joints and loss of coat. Canine leishmaniasis is a common cause of nosebleeds in dogs residing in areas where the disease is permanently present. Nosebleeds appear to be the result of multiple and variable pathogenetic factors, including ulceration of the inner lining of the nose (mucosa).

The lesions usually occur on the nose and ears. Dogs are also susceptible to visceral leishmaniasis and may be important reservoirs, but cats are rarely infected and usually do not show signs of disease. The incubation period may be months or years.

Beginning in 1999 an outbreak of visceral leishmaniasis occurred among foxhounds in foxhound club in New York, eventually resulting in 20 fatalities.

The disease is chronic and generally is characterized by emaciation and debility usually ending in death within a few years. Mortality is 70 to 90 percent in untreated animals. The disease can be controlled when properly diagnosed. With treatment a 90% recovery may be expected. A special diagnostic test for canine leishmaniasis is available.

References:
1. Akita-Treasure of Japan (Volume II)
2. A Handbook of Veterinary Parasitology: Domestic Animals of North America Henry Joseph Griffiths, Medical and Veterinary Entomology Gary Mullen, Lance Durden