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
Investigation of leishmaniasis typically begins with a detailed travel and residence history, as exposure to endemic regions is central to assessing likelihood. Physical examination may reveal patterns of skin changes, lymph node enlargement, or other signs that raise the possibility, though many findings are non-specific. Blood tests and parasite detection methods are used to confirm the presence of infection and assess how the body is responding, with the choice of tests influenced by the signs observed and the individual animal's circumstances.
Serological antibody testing
Cytology and parasite detection
PCR (polymerase chain reaction) testing
Blood biochemistry and urinalysis
Complete blood count
Options & trade-offs
Management of leishmaniasis is usually tailored to the individual dog and the pattern of signs present, with the aim of controlling parasite numbers, supporting immune function, and addressing organ-related problems. Approaches are often combined and adjusted over time as the response becomes clearer. What works well for one dog may be less practical or effective for another, depending on the severity of signs, the presence of kidney or other organ involvement, and the owner's circumstances.
Antiparasitic medication
Drugs such as allopurinol, miltefosine, and meglumine antimoniate target the Leishmania parasite and aim to reduce parasite numbers in the body. Allopurinol is typically given long-term, often for many months or years. Miltefosine, given orally alongside allopurinol, is now the first-line combination in most European treatment protocols. Meglumine antimoniate, given by injection over a period of weeks, remains an alternative, particularly where miltefosine is unsuitable or unavailable, and is sometimes used together with allopurinol in more severe cases or when initial responses are limited.
Trade-offs: Allopurinol is generally well tolerated but requires ongoing commitment and regular monitoring of kidney function and urine for crystal formation, which can occur as a side effect. Miltefosine is given orally, which some owners find easier than repeated injections, but it can cause gastrointestinal upset and is not used in pregnant or breeding animals. Meglumine antimoniate involves repeated injections, which some dogs tolerate less well, and can cause kidney or liver changes that need monitoring. None of these medications reliably eliminates the parasite completely, and relapses can occur after treatment is stopped or reduced.
Dietary protein modification
In dogs with kidney involvement or those receiving long-term allopurinol, adjusting the protein content and type in the diet can reduce the formation of certain crystals and support kidney function. This often involves feeding a diet that is moderately restricted in purines, which are metabolised to substances that can form crystals or worsen kidney disease.
Trade-offs: Dietary changes can be straightforward for some owners and dogs, whilst others find it difficult to maintain, particularly if the dog is selective about food or if multiple animals in the household are fed differently. The evidence for benefit is clearest in dogs with existing kidney compromise, and the approach is less relevant in those without organ involvement.
Immune modulation
Certain supplements and medications aim to support or shift the immune response towards a cell-mediated pattern, which tends to control Leishmania infection more effectively. Products containing nucleotides, probiotics, or other immune-active compounds are sometimes used alongside antiparasitic treatment, though the evidence base varies between products.
Trade-offs: The degree of benefit from immune modulation is not consistent across all dogs, and the mechanisms are not fully understood. Some products are expensive or require long-term use, and the response may be difficult to measure objectively. This approach is generally considered alongside rather than instead of antiparasitic medication.
Monitoring and supportive care
Regular blood tests, urine checks, and physical examinations help track disease activity, assess organ function, and detect complications early. Supportive measures such as managing skin lesions, maintaining hydration, and addressing secondary infections are adjusted according to the individual dog's needs over time.
Trade-offs: Monitoring requires repeated visits and tests, which can be time-consuming and costly, particularly as leishmaniasis is often a long-term condition. The frequency of testing may need to be higher during treatment initiation or if signs change. Some dogs remain stable with infrequent checks, whilst others require closer observation.
Topical insect repellents and environmental measures
For dogs living in or travelling to endemic areas, products such as permethrin-impregnated collars or spot-on treatments can reduce sandfly bites and lower the risk of new infections or reinfection. Keeping dogs indoors during peak sandfly activity times—typically dusk and dawn in warm months—may also reduce exposure.
Trade-offs: These measures are more relevant for prevention or for dogs at ongoing risk of exposure, and less so for those already infected and living outside endemic zones. Some products are not suitable for households with cats, as permethrin can be toxic to them. The protective effect is not absolute, and infected dogs can still develop or progress in disease despite precautions.
Common misconceptions
"A positive leishmaniasis test means the dog will definitely become ill or cannot live a normal life."
Many dogs that test positive for Leishmania infection remain without clinical signs for years or even their entire lives, particularly those with low antibody levels and no organ involvement. The presence of antibodies or parasite DNA indicates exposure and infection but does not predict the course in an individual dog. Some dogs require little or no treatment and continue normal activity, whilst others develop signs that need ongoing management.
"Leishmaniasis can be cured completely with medication."
Current treatments aim to control parasite numbers and manage signs rather than eliminate the infection entirely. Most dogs that respond to treatment show improvement or stabilisation, but the parasite often persists at low levels in the body. Relapses can occur, particularly if treatment is stopped or if the immune system is compromised by other illness or stress. Long-term or intermittent treatment is common.
"Dogs with leishmaniasis are a direct risk to other dogs or to people in the household."
Leishmaniasis is not transmitted directly from dog to dog or from dog to person through ordinary contact. Transmission requires a sandfly vector, which is not present in most non-endemic regions. Infected dogs living in areas without the appropriate sandfly species pose negligible risk to other animals or people. Rare cases of non-vector transmission have been documented—such as through blood transfusion or from mother to puppy—but these are uncommon and not part of everyday risk.
Related conditions
Ehrlichiosis
Ehrlichiosis is another tick-borne infection that can produce overlapping signs with leishmaniasis, including weight loss, lethargy, and changes in blood cell counts. In regions where both parasites circulate, dogs may occasionally carry both infections at once, and the clinical picture can be difficult to separate without specific testing.
Babesiosis
Babesiosis shares the pattern of a blood-borne parasitic infection transmitted by vectors, and both conditions can lead to anaemia, lethargy, and immune-mediated complications. Dogs travelling to or living in endemic areas may be exposed to multiple parasitic infections simultaneously, which can complicate the interpretation of signs and test results.
Glomerulonephritis
Leishmaniasis can trigger glomerulonephritis—inflammation of the kidney's filtering units—through immune complex deposition, leading to protein loss in the urine and progressive kidney dysfunction. This kidney involvement is one of the more serious complications that can develop in dogs with chronic or poorly controlled leishmanial infection.
Immune-Mediated Polyarthritis
Immune-mediated polyarthritis can develop in some dogs with leishmaniasis, as the immune response to the parasite may generate inflammation in multiple joints. Joint pain, stiffness, or lameness in a dog with other features consistent with leishmaniasis may reflect this immune-mediated component rather than direct parasitic invasion of the joints.
If the pattern of signs or test results raises the possibility of leishmaniasis, understanding the broader context of immune and inflammatory responses can be useful. The Immune & Inflammatory Health section explores how the body responds to chronic infections and how those responses shape the signs seen over time. For dogs with kidney involvement, the pages on kidney function and protein loss may offer additional context. Travel history and future plans may also be worth revisiting, particularly if ongoing exposure to endemic regions is possible.