Leishmaniasis

Leishmaniasis is an infection caused by a microscopic parasite called Leishmania, transmitted through the bite of certain sandflies. The parasite can spread through the body and may affect the skin, internal organs, or both, depending on how the immune system responds. It is most commonly seen in dogs that have travelled to or lived in regions where these sandflies are present, particularly southern Europe and parts of the Mediterranean. Owners often first notice skin changes — such as hair loss, scaling, or sores that do not heal — or more general signs like weight loss, lethargy, or changes in appetite. Some dogs show few or no signs for months or even years after exposure, while others develop a range of problems relatively quickly. The signs can be subtle and may develop gradually, which sometimes makes the picture unclear at first. This page explores the patterns that may raise the possibility of leishmaniasis, what is happening inside the body when the parasite is present, how the infection is investigated through blood tests and other methods, and the range of approaches that exist for managing it over time.