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Leishmaniasis, also called leishmaniosis in veterinary writing, is an infection caused by single celled parasites of the genus Leishmania. The species that matters most for dogs is Leishmania infantum. The parasite lives in two forms during its life cycle, one adapted to the sand fly and one that lives inside the dog's own immune cells, where it multiplies and spreads through the body. Dogs are the main reservoir host for this parasite, which means infected dogs, including dogs that look healthy, can pass the parasite on to sand flies that bite them. The infection is also a zoonosis, a disease shared between animals and people, although people are usually infected by sand fly bites rather than directly by contact with a dog.
After infection the parasite can stay quiet for months to years before illness appears, and many infected dogs never become sick. The Merck Veterinary Manual reports that leishmaniosis is endemic in more than 89 countries and that approximately only 10 percent of infected dogs develop clinical signs. When illness does develop it can involve the skin, eyes, joints and internal organs, and the kidneys are a central concern, because immune related kidney damage is believed to be the main cause of death in dogs that become seriously ill. Because signs vary so widely, leishmaniasis is easy to confuse with other conditions, and testing is essential for any dog with a compatible history and travel or import background. Skin changes are often the first thing an owner notices, and they can look deceptively ordinary, like dandruff, thinning hair or a sore that keeps crusting over. The deeper risk is quieter. As infection progresses, immune complexes circulate and settle in the kidneys, joints and blood vessels, which is why a dog can have modest skin signs and serious internal disease at the same time. Dogs imported from endemic regions can carry the parasite into countries where the disease is otherwise rare, so veterinarians in non endemic areas still ask about a dog's origin and travel history. Testing also matters before a dog donates blood or is bred, because both routes can pass the infection to another dog without any sand fly being involved.
Leishmaniasis is caused by Leishmania parasites, most importantly Leishmania infantum in dogs. The usual route of infection is the bite of an infected female sand fly, a tiny biting insect that feeds mainly from dusk to dawn in warm months. The fly deposits the parasite into the skin while feeding, and the dog's immune response then decides whether infection stays silent or progresses to disease. Transmission from a mother dog to her puppies before birth is also confirmed, and spread through blood transfusion or direct contact has been reported. Dogs living in or traveling to endemic regions, dogs imported from those regions and dogs that spend evenings outdoors face the highest exposure.
Breeds and dogs at higher risk: No breed is immune, and risk follows exposure more than breed. Dogs that live in, travel to or are imported from endemic areas of the Mediterranean, the Middle East, and Central and South America are at highest risk. In the United States, Foxhounds have been identified most often, linked to transmission from mother to puppy within kennels.
Diagnosis needs an integrated approach, because no single test answers every case. The veterinarian starts with the history, including travel or import background, and a full examination for skin lesions, lymph node enlargement and eye changes. Routine blood work and urinalysis look for the patterns this disease often produces, such as anemia, high globulin proteins, low albumin and protein in the urine that signals kidney involvement. Specific testing usually combines quantitative antibody testing, which is most sensitive when compatible signs are present, with PCR testing that detects parasite DNA in blood or tissue. Examining lymph node, skin or bone marrow samples under a microscope can sometimes show the parasites directly. Results are interpreted together. A positive antibody test in a healthy dog may show exposure without active illness, while a sick dog with low antibody levels may still need PCR or tissue sampling. Kidney staging is part of the same workup because it strongly influences treatment choices.
Treatment controls the parasite and the damage it causes, but it rarely removes every parasite from the body. The Merck Veterinary Manual states that treated dogs can remain carriers of infection and can relapse, so treatment is best understood as long term control rather than a guaranteed cure. Standard protocols combine an antiprotozoal medication, such as meglumine antimoniate or miltefosine where available, with allopurinol, a medication that interferes with parasite growth and is often continued for many months. Kidney disease, the most serious complication, is staged and managed alongside parasite treatment with diet changes, fluids and medication chosen for the individual dog. Other care can include treatment for skin and eye lesions, pain relief for sore joints and management of bleeding problems. Response is monitored with repeat examinations, blood work, urine protein checks and antibody levels. Drugs for this disease have meaningful side effects, including effects on the kidneys, so dosing and monitoring must stay under veterinary direction. Availability of some medications differs by country, and your veterinarian will explain which protocol is legal and practical where you live. Owners should be prepared for a long course of care. Improvement often comes gradually over weeks, kidney values are rechecked on a set schedule, and stopping medication early because a dog looks better is a common route to relapse, so any change should be agreed with the veterinary team first.
Living with leishmaniasis means steady monitoring and protection against sand flies. Keep every recheck appointment, since blood and urine tests track kidney function and treatment response even when your dog looks well. Give long term medication exactly as prescribed and do not stop it because signs have faded. Use a veterinarian approved sand fly repellent insecticide, especially in endemic areas, and keep your dog indoors from dusk to dawn during sand fly season when practical. Watch for returning skin sores, nosebleeds, appetite change or increased drinking, and report them early. An infected dog should not be used as a blood donor or for breeding, because both routes can pass the parasite on.
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Most cases involve living in, traveling to or being imported from an endemic region. However, puppies can be infected before birth by an infected mother, and infection has also been reported after blood transfusion. In the United States, kennel Foxhounds have carried infection without sand fly spread, so a travel history is helpful but not the only route to consider.
Leishmaniasis is a zoonosis, but people are usually infected by the bite of an infected sand fly, not by touching or living with a dog. Infected dogs matter because sand flies that bite them can pick up the parasite and later bite people. Sand fly control around the home protects both dogs and people in endemic areas.
Treatment can bring strong improvement and long periods of good health, but it usually does not eliminate every parasite. The Merck Veterinary Manual notes that treated dogs can remain carriers and can relapse months to years later. Ongoing monitoring, long term medication when advised and sand fly protection are therefore part of care even after signs resolve.
Prevention centers on stopping sand fly bites. Veterinarian approved repellent insecticides, including certain collars and spot on products, reduce bites in endemic areas. Keeping dogs indoors from dusk to dawn during the sand fly season also helps. Vaccines against this disease are marketed in some countries, such as parts of Europe and Brazil, but availability and licensing vary by country.
The immune response to the parasite produces complexes that lodge in the kidneys and cause glomerulonephritis, a form of kidney inflammation. Kidney damage develops in many infected dogs and severe kidney failure is believed to be the main cause of death from this disease. Urine protein checks and kidney values are therefore monitored from diagnosis onward.
This page is general information drawn from the published guidance of the organizations listed under Sources below. It is not veterinary advice, and it does not replace your own veterinarian, who knows your dog. If your dog may have eaten something toxic, contact your veterinarian, the ASPCA Animal Poison Control Center on (888) 426-4435, or the Pet Poison Helpline on (855) 764-7661 straight away. A consultation fee may apply on the helplines. If your dog is struggling to breathe, has collapsed, is having a seizure that will not stop, or has a swollen belly with retching that brings nothing up, go to an emergency veterinarian now and do not wait to finish reading.
Last updated: November 2026. Facts on this page were checked against the sources listed above. How we work: our methodology.