CONDITION
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.
Why this matters now
Leishmaniasis tends to be seen in dogs that have travelled to or lived in endemic regions, particularly southern Europe, the Mediterranean basin, and parts of South America and Asia. The infection can occur at any age, though signs often appear months to years after exposure, as the incubation period is highly variable. Dogs that have spent time in areas where sandflies are active—typically warm months in endemic zones—carry the highest risk. There is no strong breed predisposition, though some research suggests certain breeds may be more susceptible to developing severe disease once infected.
The progression of leishmaniasis varies widely between individual dogs. Some animals remain without visible signs for extended periods, whilst others develop skin changes, weight loss, or signs of organ involvement within months of infection. The infection may progress slowly over years, with periods where signs appear stable or even improve, followed by deterioration. In some cases, signs emerge suddenly after a long silent phase, often triggered by stress, illness, or other factors that affect immune function.
Signals & patterns
Early signals
Patchy hair loss and scaling
Owners may notice areas where the coat becomes thin, particularly around the face, ears, or pressure points like elbows. The skin underneath often appears dry, with fine silvery scales that do not resolve with routine care.
Slow-healing sores or crusts
Small wounds, scratches, or areas of skin irritation may fail to heal at the expected rate, sometimes developing crusts or thickened patches. These changes can appear on the ears, muzzle, paw pads, or other areas and may persist for weeks.
Gradual weight loss
A dog may lose weight steadily over weeks or months, even when appetite remains relatively normal. The change can be subtle at first, becoming more apparent when comparing the dog's condition to previous months.
Reduced energy or stamina
A previously active dog may show less interest in walks, play, or activity. The change often develops gradually, and owners may initially attribute it to ageing or seasonal variation.
Overgrown or brittle nails
The nails may grow more quickly than usual or become thickened, curved, and prone to splitting. This change can affect one or several paws and may be noticed during routine nail trimming.
Later signals
Swelling around the eyes or face
Some dogs develop a subtle puffiness or swelling around the eyelids, muzzle, or head. This can give the face a slightly altered appearance and may be accompanied by redness or thickening of the skin.
Nosebleeds or nasal discharge
Bleeding from one or both nostrils may occur spontaneously or after minor activity. The discharge may be clear, blood-tinged, or contain small clots, and it can be intermittent or persistent.
Limping or joint stiffness
A dog may develop lameness in one or more legs, or show reluctance to move after rest. The stiffness can shift between limbs and may be accompanied by swelling around joints or bones.
Increased thirst and urination
Owners may notice the dog drinking more water than usual and needing to urinate more frequently. This pattern can develop gradually and may signal involvement of the kidneys, which are sometimes affected in later stages.
Click to read about the biological mechanisms
How this is usually investigated
Options & trade-offs
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