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The important points, first
- Sand flies bite mainly after sunset. In risk areas they are usually active from April to November, and all year round in some places.
- Repellent pyrethroid collars and spot-ons reduce bites and new infections. Your veterinarian decides which to use and how often to renew it.
- During the risk season, keep your dog indoors at dusk and dawn if you can.
- An infected dog can look healthy for months or years. Weight loss, skin problems and overgrown nails should be checked.
- Some pyrethroid parasite products registered for dogs only are toxic to cats.
How it spreads and why it matters in Italy
In Europe, canine leishmaniosis is caused mainly by Leishmania infantum. It is transmitted by female sand flies of several species when they bite to feed on blood. According to the ESCCAP guidelines these insects are active at temperatures of at least 15 °C and look for hosts mostly after sunset. By day they hide in dark, humid places such as cracks in walls, woodpiles, stables and cellars. Dogs are the main reservoir of the parasite, which can also infect humans.
Until a few decades ago the disease was considered typical of central and southern Italy and the islands. An Italian study analysed more than 80,000 leishmaniosis tests performed between 2009 and 2019 by two reference laboratories. Positive results were found in 21.6% of samples from the north, 29.6% from the centre and 28.2% from the south and islands. The authors conclude that leishmaniosis is now endemic in some northern areas too, and that prevention is needed even where few cases have been seen so far.13
How long the risk season lasts
The sand fly season varies from year to year and from place to place. In endemic areas it usually runs from April to November. ESCCAP adds that in some Mediterranean countries, including Italy, dogs may need protection all year round.
The protection period should therefore be decided with your veterinarian, based on where your dog lives and travels. A dog spending its holidays in an endemic area is at higher risk even if it lives elsewhere. Dogs living outdoors, hunting dogs, strays and dogs adopted from shelters in risk areas are also more exposed.1
Signs not to overlook
Between infection and disease there can be anything from three months to several years, and in endemic areas many infected dogs look healthy. The first sign, when noticed, is often a small lesion at the bite site, usually on the ears, nose or belly. It heals by itself within a few weeks and is easily mistaken for a tick or other insect bite.
As the infection spreads, dogs may develop enlarged lymph nodes, weight loss, poor appetite and weakness. The skin may show hair loss and scaling, usually without itching, and the nails may grow abnormally. Other possible signs are nosebleeds, lameness, eye problems and, when the kidneys are involved, more thirst and more urine. Without treatment the disease can be fatal. For diagnosis the veterinarian uses blood tests and specific tests; antibodies usually appear three to five months after infection.1
How to protect your dog
According to ESCCAP, the most promising strategy is preventing bites with repellent products. The World Association for Veterinary Dermatology guidelines, based on the available clinical trials, recommend certain pyrethroid collars and a spot-on in endemic areas, as they reduce new infections. Duration varies a lot between products: a collar can protect for months, a spot-on for a few weeks. Intervals and use should be agreed with your veterinarian and checked on the product leaflet. Take care in homes with cats, because some pyrethroids for dogs are toxic to cats.
During the risk season ESCCAP also advises keeping dogs indoors at dusk and dawn, fitting fine-mesh screens to doors and windows and removing rubbish and organic material near the home. There is also a vaccine for seronegative dogs over six months of age, with a yearly booster; ESCCAP considers repellents and vaccination together the best way to control the disease. If your dog tests positive, tests and treatment are for the veterinarian to assess, and in Italy veterinarians must report new cases to the authorities.124
Sources and checks
Numbers in the text lead to the exact source. Commercial blogs and social posts are not used as evidence.
- 1Veterinary guideline
ESCCAP Guideline 05: Control of Vector-Borne Diseases in Dogs and Cats (5th edition, 2024)
European Scientific Counsel Companion Animal Parasites (ESCCAP) · Sand fly biology, April–November or year-round season, most exposed dogs, travel, clinical signs, diagnosis, repellents, vaccine, reporting obligation in Italy.
Link checked on 16 Sept 2026 - 2Veterinary guideline
World Association for Veterinary Dermatology Consensus Statement for Diagnosis, and Evidence-Based Clinical Practice Guidelines for Treatment and Prevention of Canine Leishmaniosis
Veterinary Dermatology (2025) · PubMed PMID 40745695 · Guidelines based on clinical trials: two pyrethroid collars and one spot-on recommended in endemic areas; role of vaccines. Authors declare industry relationships.
Link checked on 16 Sept 2026 - 3Peer-reviewed research article
Leishmania infantum and Dirofilaria immitis infections in Italy, 2009–2019: changing distribution patterns
Parasites & Vectors (2020) · PubMed PMID 32293524 · Over 90,000 serological tests, more than 80,000 for leishmaniosis: disease endemic in parts of northern Italy too; positive test rates by macro-area. One author is employed by a pharmaceutical company.
Link checked on 16 Sept 2026 - 4Veterinary guideline
ESCCAP Guideline 03: Control of Ectoparasites in Dogs and Cats (7th edition, 2022)
European Scientific Counsel Companion Animal Parasites (ESCCAP) · Warning: some concentrated pyrethroids registered for dogs are toxic to cats.
Link checked on 16 Sept 2026
This guide does not recommend products or doses and cannot replace an examination. Choice of protection, tests and any treatment is for your veterinarian.