What is Leishmaniasis?

Visceral leishmaniasis is caused by the protozoan Leishmania infantum and transmitted by the bite of infected sand flies (Phlebotomine sand flies, most active at dusk and at night). It is considered a zoonosis because the same parasite can infect humans, although dogs do not transmit the disease directly to people — the sand fly is the necessary link in transmission. The disease is endemic in parts of southern Europe, Latin America, Asia, Africa, and the Middle East.

Signs in dogs tend to be progressive and varied: weight loss despite a normal appetite, excessive nail growth (onychogryphosis), skin lesions and scaling (especially around the eyes and ears), hair loss, non-healing sores, enlarged lymph nodes and spleen, and, in advanced stages, kidney failure. Many infected dogs remain asymptomatic for months or years.

There is no definitive cure — treatment controls symptoms and reduces the parasite load, but the dog usually remains a carrier. That is why prevention with sand fly repellent collars and topical products is essential in endemic areas. See a veterinarian for evaluation and blood testing if a dog living in or having traveled to an endemic region has progressive weight loss, persistent skin lesions, or unusually long nails.