Leishmaniosis (Visceral Leishmaniasis) in Dogs
Leishmaniosis is a chronic, severe disease of humans, dogs, and certain rodents caused by single-celled protozoa of the genus Leishmania. Visceral leishmaniosis is characterized by skin lesions, disease of the lymph nodes, weight loss, anemia, lameness, and kidney failure. Occasionally, there may be bleeding from the nose or eye lesions.
Infection in dogs is prevalent in Central and South America, the Middle East, Asia, and the Mediterranean region. The disease is found in Foxhounds in North America. Isolated cases are diagnosed around the world in animals that have visited areas where the disease is well established.
Leishmaniosis can be transmitted from dogs to people. Humans most frequently catch this disease when they are bitten by a sand fly or other insect that has previously bitten an infected animal or human. While there are only a very few human or animal cases in the US each year, worldwide there are about 1.5 million cases of cutaneous leishmaniosis and 500,000 cases of visceral leishmaniosis a year. Most human cases of visceral leishmaniosis are reported in India, Bangladesh, Nepal, Sudan, and Brazil.
The incubation period is quite variable, ranging from 3 months to several years. The signs vary but may include skin lesions, weight loss, poor appetite, local or generalized disease of the lymph nodes, eye lesions, kidney failure, nosebleed, lameness, and anemia. Occasionally, some dogs have chronic diarrhea or liver failure. The most common skin lesions are areas of baldness with severe dry skin shedding, usually beginning on the head and extending to the rest of the body. Other animals develop chronic ulceration, located particularly on the head and limbs. The signs invariably progress slowly.
The most reliable diagnostic test for canine leishmaniasis is direct observation of the parasite in bone marrow or lymph node smears. If your veterinarian suspects leishmaniosis, samples of bone marrow or fluid from the lymph nodes will be taken to confirm the diagnosis.
Drug treatment is available for dogs with visceral leishmaniosis and may last up to 6 months. Relapses after treatment are common. In areas where the disease is common, rapid treatment of infected dogs, control of stray and homeless dogs, and control of sand flies are recommended. At present, there is no effective vaccine.