Leishmaniasis, caused by the protozoan Leishmania, affects not only dogs but humans and rodents too. This chronic disease has symptoms such as anemia, severe weight loss and lesions on the skin. It may result in lymph node disease and kidney failure too. Leishmaniasis is widespread in certain geographic regions such as Asia, the Middle East and the Mediterranean. It occurs in Central and South America too. Dogs in other areas may develop it if they have been to the disease-prone areas. In North America, Leishmaniasis mainly occurs in foxhounds.
Dogs can spread this infection to humans too. However, most cases of human infection originate from biting insects like sand flies. When they bite a person after biting infected animals or other people with the disease, the protozoa gets transferred. Incidence of Leishmaniasis, in both humans and animals, is rare in the United States, but there are about 500,000 visceral leishmaniasis cases reported worldwide every year, the bulk of it from Asian countries like Bangladesh, India and Nepal. Brazil and Sudan are the other high incidence countries. Over one and half million cases of another type of the disease called cutaneous leishmaniasis also occur world over.
The disease has a long incubation period of 3 months to many years. Among the symptoms of visceral Leishmaniasis, the most obvious is the development of lesions on the skin. In dogs, the characteristic bald patches of skin with shedding of dry skin usually start on the animal’s head and then appear in other parts as well. Chronic ulceration is common in some of the other infected animals. They occur mostly on the heads and the legs. Other symptoms include loss of appetite, anemia, weight loss, eye lesions and disease of the lymph nodes. Dogs may have diarrhea and bleeding from the nose. They may become lame too. Kidney and liver failure are two of the serious symptoms of severe disease.
Testing of canine leishmaniasis is done by microscopic examination of the fluid drawn from the lymph nodes, or by bone marrow testing. If the presence of the organism is observed in the above, the diagnosis is confirmed.
There is no vaccine against visceral leishmaniasis. The disease is treated with a long-term drug regimen that may even continue for 6 months. The disease may relapse after the dog recovers from a bout of it. Control measures include controlling sand fly population and stray dogs that may harbor the protozoan. The infected animals should be treated immediately to prevent the organism spreading to others.