Leishmaniasis in Dogs: Symptoms, Sand Flies and Prevention

A summer road trip through Spain or southern Italy, a rescue dog adopted from a shelter abroad, or a foxhound from a hunting kennel, and then, months later, a dog that keeps losing weight and has thinning fur. Could it be leishmaniasis? How would your dog have caught it? And how do you protect them?

Leishmaniasis is a parasitic disease spread mainly by the bite of tiny sand flies, common around the Mediterranean. It develops slowly, sometimes over years, and mostly shows up as weight loss, tiredness and skin problems. In the US and the UK, it is mostly seen in dogs that traveled or were imported from endemic countries, and in some foxhound kennels. The parasite is rarely eliminated completely, but most treated dogs recover, and the outlook is good when the disease is caught early.

What is leishmaniasis in dogs?

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Canine leishmaniasis (vets often say “leishmaniosis”) is caused by a microscopic parasite, Leishmania infantum. Its usual carrier is the sand fly, a small insect about a tenth of an inch long. Sand flies bite mostly after sunset and rest during the day in dark, damp spots such as cracks in stone walls, woodpiles, stables and cellars.

Once inside the body, the parasite settles in immune cells and can affect many organs: the skin, lymph nodes, spleen, liver and, most importantly, the kidneys.

Infection does not always mean illness. The LeishVet expert guidelines stress that many infected dogs never show signs, while others become seriously ill. It all depends on how each dog’s immune system responds.

Is leishmaniasis a risk for dogs in the US?

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Yes, but in a specific way. Leishmaniasis made headlines in 1999, when an outbreak hit a foxhunting kennel in New York. A CDC-published investigation later screened more than 12,000 dogs and found infected foxhounds in 18 states and 2 Canadian provinces.

According to the Companion Animal Parasite Council, more than 20% of at-risk foxhounds now test positive, and in North America the parasite spreads mainly from mother to pups and directly between dogs. Sand flies do live in parts of the eastern US, but transmission by sand fly bites has not been confirmed there.

For most pet owners, the main risk comes from travel and adoption. CAPC advises vets to consider leishmaniasis in any dog that has been to an endemic area, which includes the Mediterranean basin and parts of Latin America. If you adopted a dog from southern Europe or South America, or plan to take your dog on a trip there, mention it to your vet.

What about the UK and Europe?

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Around the Mediterranean, leishmaniasis is common: Spain, Portugal, southern France, Italy and Greece are all endemic areas. The ESCCAP guidelines on vector-borne diseases place the sand fly season from April to November in these regions, which means mild fall evenings still carry a risk.

In the UK, sand flies are not currently present, and the UK Health Security Agency rates the risk to the population as very low. Cases are still being diagnosed, though: a study of UK veterinary data counted 368 clinical cases between 2010 and 2022, more than half of them in dogs that had visited, or were rescued from, Spain, Greece, Cyprus or other southern European countries.

Planning a European trip with your dog? Add sand fly protection to your dog travel checklist, along with the pet passport and vaccines.

How is leishmaniasis transmitted?

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In endemic areas, a female sand fly picks up the parasite by biting an infected dog, then passes it to the next dog it bites. Dogs are the main reservoir of the disease.

Other routes exist: from mother to puppies during pregnancy, through transfusion of infected blood, and through mating. These routes explain why cases appear in places without sand flies, such as US kennels or UK homes that took in a rescue dog.

The time between infection and the first signs is unusually long. ESCCAP describes an incubation period ranging from three months to several years. A dog bitten during a summer vacation may not show any sign until the following year.

What are the symptoms of leishmaniasis in dogs?

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Signs vary widely and appear gradually. According to LeishVet, skin problems are the most common, but the disease often affects the dog’s overall condition. Signs to watch for:

• weight loss and loss of appetite;
• weakness and muscle loss;
• hair loss and flaky, peeling skin;
• swollen lymph nodes;
• nails that grow abnormally long;
• nosebleeds;
• red or irritated eyes (eyelids, conjunctivitis);
• drinking and urinating more than usual.

That last one deserves special attention. LeishVet notes that chronic kidney failure is the main cause of death in dogs with leishmaniasis. Unusual thirst can be a sign that the kidneys are already affected.

None of these signs is specific to leishmaniasis on its own. It is the combination, plus a history of travel to or life in an endemic area, that should make you think of it. To tell routine changes from warning signs, keep a list of the dog symptoms you should never ignore.

How do vets diagnose and treat it?

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Your vet will start with a physical exam, then blood tests. Antibody testing (serology) usually comes first, ideally with a quantitative result, and can be completed by a PCR test that looks for the parasite’s DNA. Blood work and a urine test then show how well the kidneys are working and help stage the disease.

Treatment usually combines a drug that acts against the parasite for a few weeks with a second drug, allopurinol, given for several months. Your vet will choose the medications and duration based on the stage of the disease and kidney function. The parasite is rarely eliminated completely and relapses are possible, so treated dogs need checkups, usually every six to twelve months. According to the LeishVet guidelines, most dogs recover after treatment and the outlook is good in the early stages; it becomes guarded to poor once the kidneys are affected.

How to protect your dog from sand flies

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Prevention is about one thing: avoiding sand fly bites. ESCCAP recommends the following throughout the risk season when you live in or travel to an endemic area:

• a parasite-control product with a repellent effect against sand flies (an impregnated collar or a spot-on), chosen with your vet;
• keeping your dog indoors at dusk and dawn throughout the risk season;
• fine-mesh screens on windows and doors.

Not every flea and tick product repels sand flies, so check with your vet before you leave. Ongoing parasite control also protects against ticks that carry babesiosis and other tick-borne diseases.

Is there a vaccine for leishmaniasis?

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In Europe, yes. According to the LeishVet vaccine page, updated in February 2026, the only vaccine currently available there is LetiFend: one injection, then a yearly booster, with an estimated 72% efficacy against clinical disease. It is meant for dogs over six months old that test negative. It adds to repellents but does not replace them. US owners traveling to Europe for a long stay can ask their vet whether it is relevant.

Notice earlier when your dog is losing condition

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What makes leishmaniasis tricky is how slowly it moves. A little weight loss, a dog less eager to go out, longer naps: these changes build up over weeks and are easy to miss day to day.

Because the disease progresses quietly, daily health tracking helps you spot a trend. Worn around the clock, the Invoxia Biotracker records your dog’s activity, sleep, and heart and breathing rates at rest. A drop in activity that settles in, or sleep that keeps getting longer week after week, is worth reporting to your vet, especially after a trip to an endemic area.

The Biotracker does not detect leishmaniasis and never makes a diagnosis. It gives you clear reference points on what is normal for your dog, so you can see your vet sooner and describe exactly what you noticed. On vacation, its GPS works in more than 30 countries (not in Italy or the UK), weighs just 1.3 oz (37 g) and lasts up to 15 days on a charge. To go further, learn how to monitor your dog’s health every day.

FAQ — leishmaniasis in dogs

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Can humans catch leishmaniasis from dogs?

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Leishmania infantum can infect people, but in endemic areas transmission happens through sand fly bites, not through everyday contact with a dog. CAPC notes that no locally acquired human cases of the visceral form have been reported in the US. Protecting your dog from bites also limits the parasite’s spread around your home.

Can an infected dog pass it to other dogs?

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Not through ordinary contact. Direct transmission between dogs is possible through pregnancy, mating or blood transfusion.

How long can a dog live with leishmaniasis?

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It depends on the stage at diagnosis. In the early stages, with healthy kidneys, the outlook is good with treatment and regular checkups. It is guarded to poor once kidney failure is present.

Should I test a dog adopted from Spain or Greece?

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Ask your vet. Because incubation can last months or years, a negative test at adoption does not rule out infection. Your vet will suggest the right test and timing.

Does a repellent collar fully protect my dog?

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A suitable repellent collar greatly reduces the risk of bites if it is put on before exposure and replaced on time. It works best combined with keeping your dog indoors at dusk and dawn and, in Europe, vaccination if your vet recommends it.

In summary

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Leishmaniasis is a parasitic disease spread mainly by sand flies around the Mediterranean, from April to November. In the US and the UK, it mostly affects dogs that traveled or were imported from endemic areas, and some foxhound kennels where it passes from dog to dog. It develops slowly and shows up as weight loss, tiredness, skin lesions and, later, kidney damage. Repellents, keeping your dog indoors at dusk and dawn and, in Europe, vaccination are the best protection. If in doubt, especially after a trip or an adoption from abroad, see your vet: early diagnosis makes treatment more effective.

This article is for information only and does not replace a visit to your veterinarian.