What is leptospirosis?
Updated By PetymFacts checked against official sources on
Quick answer
Leptospirosis is a bacterial disease spread through the urine of infected animals, especially rats. Dogs catch it from contaminated water, soil, wounds or damaged skin, and cases rise in India's monsoon. It mostly damages the kidneys or liver and can pass to people. A yearly vaccine, started as two doses a few weeks apart, reduces the risk.
Also called lepto, Leptospira, rat fever, Weil's disease.
Key facts
- Dogs catch it through contaminated urine or water, bite wounds or damaged skin, or by eating infected meat; the bacteria survive a long time in surface water. Merck Veterinary Manual
- Kidney trouble is the most common pattern; liver failure can turn the gums, skin and eyes yellow. Merck Veterinary Manual
- An infected dog can shed the bacteria in its urine for weeks or months, and it can spread to people. Merck Veterinary Manual
- The Health Ministry's 2026 pre-monsoon advisory asks pet owners to keep pet areas clean and rodent-free and to consider vaccinating. Ministry of Health and Family Welfare
- WSAVA calls the vaccine core where the disease occurs, the types are known and suitable vaccines exist; it is given yearly. WSAVAstudy
- ACVIM's 2023 consensus advises yearly vaccination for all dogs. ACVIM (Journal of Veterinary Internal Medicine, 2023)study
How do dogs get leptospirosis in India?
Rats and other animals carry Leptospira bacteria in their kidneys and pass them in urine. In the monsoon, that urine washes into puddles, drains and flooded streets, where the bacteria survive a long time. A dog wading through floodwater, drinking from a puddle, or with a cut or soft, wet skin on its paws can be infected. Eating a dead rat is another route.
Cases rise in the monsoon in people as well as dogs: India's National Centre for Disease Control runs a programme for it, and outbreaks in people followed the Kerala floods. A city dog that lives in a flat is not out of reach: its walks can pass the same drains, puddles and garbage points that rats use (Petym's practical note).
What are the signs of leptospirosis in a dog?
Signs can be mild or sudden and severe. After floodwater or a rat encounter, watch closely.
If Sluggishness, loss of appetite, vomiting
See a vet the same day, and say if the dog walked through floodwater. Merck Veterinary Manual
If Drinking and urinating a lot more, or passing very little urine
Urgent: these point to kidney damage. Merck Veterinary Manual
If Yellow gums, skin or whites of the eyes
Emergency: a sign of liver failure. Merck Veterinary Manual
If Dehydration or a painful back
See a vet urgently. Merck Veterinary Manual
Can people catch leptospirosis from a dog?
Yes. It is a zoonosis: a disease that passes between animals and people. An infected dog can shed the bacteria in its urine for weeks or months. Wear gloves to clean up urine, wash your hands well, keep children away from the dog's urine, and see your own doctor if you feel unwell after caring for a sick dog. The US CDC's advice for pet owners covers the same steps.
Should my dog have the leptospirosis vaccine?
WSAVA's 2024 guidelines moved it from non-core to core wherever the disease occurs, the disease-causing types are known and a suitable vaccine is available. In India the types have not been firmly established: most Indian studies measured antibodies, which show exposure but cannot reliably tell which types cause disease. ACVIM advises yearly vaccination for all dogs, ICAR-IVRI advises it yearly in high-risk areas, and the Health Ministry asks owners to consider it.
The first course is two doses 2 to 4 weeks apart, then a booster every year; vaccines carry one to four types, and L4 on a card means four. If 18 months or more have passed since the last dose, WSAVA advises restarting with two doses. Time the booster before the monsoon.
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Questions owners ask
How do dogs get leptospirosis in the monsoon?
- From water or soil contaminated with the urine of infected animals such as rats, through cuts or damaged skin, or by drinking it. In India's monsoon the bacteria wash into puddles and floodwater and survive there a long time, so cases rise in dogs and in people during the rains.
Can my dog give me leptospirosis?
- Yes. An infected dog can shed the bacteria in its urine for weeks or months. Wear gloves to clean up urine, wash your hands well, keep children away, and see your own doctor if you feel unwell after caring for a sick dog, mentioning the dog's illness.
Is the leptospirosis vaccine given every year?
- Yes. It protects for a shorter time than the core viral vaccines, so it is repeated yearly after a first course of two doses 2 to 4 weeks apart. If 18 months or more pass without a booster, WSAVA advises starting again with two doses, so book it before the monsoon.
Can a vaccinated dog get leptospirosis?
- It is possible. There are many types of Leptospira, and each vaccine covers one to four of them; in India the types causing disease have not been firmly established. The vaccine still lowers the risk. Avoiding floodwater and rats matters as much as the vaccine.
Keep reading
Related terms
More in vaccines and parasites
- BabesiosisBabesiosis is a disease of dogs caused by Babesia, tiny parasites that live in and destroy red blood cells. It is spread mainly by ticks, and in India one species, Babesia gibsoni, also spreads through dog fights and blood transfusions. Signs are anaemia with pale gums, weakness, jaundice and red or brown urine. Dogs that recover can relapse.
- Booster vaccineA booster is a repeat dose of a vaccine that tops up or confirms a pet's protection. Puppies and kittens get a booster at about 26 weeks after their first course. After that, modern core vaccines for distemper, parvovirus and panleukopenia protect for years, while leptospirosis, kennel cough and most killed vaccines need a booster every year.
- Brown dog tickThe brown dog tick, Rhipicephalus sanguineus, is the most common tick on dogs in the tropics, including India. Unlike most ticks it lives and breeds indoors, in homes and kennels, as well as outdoors. It spreads ehrlichiosis and one form of babesiosis, the infections Indian owners call tick fever, so tick control is needed all year.
- Core vaccinesCore vaccines are the vaccines every dog or cat should have, wherever it lives, because they protect against widespread, serious diseases. For dogs they cover distemper, adenovirus and parvovirus; for cats, panleukopenia, herpesvirus and calicivirus. In India rabies is core for both, and WSAVA also treats leptospirosis vaccine as core for dogs where the disease is endemic.
- DewormingDeworming is giving a pet medicine, chosen by your vet, to kill intestinal worms such as roundworms, hookworms and tapeworms. Puppies can be born with roundworms and catch more from their mother's milk, so deworming starts in the first weeks of life. Some dog and cat worms can infect people, especially children, so regular deworming protects the family too.
- DHPPi vaccineDHPPi is the combined core vaccine for dogs printed on many Indian vaccine cards. The letters stand for distemper (D), hepatitis from canine adenovirus (H), parvovirus (P) and parainfluenza (Pi). DHPPiL adds leptospirosis (L). It is the same vaccine group that US cards call DHPP or DA2PP, and puppies start it at 6 to 8 weeks.
- EhrlichiosisEhrlichiosis is a disease of dogs caused by Ehrlichia canis, a bacterium carried by the brown dog tick. Signs appear 1 to 3 weeks after infection: fever, dullness, bleeding such as nosebleeds or bruising, and enlarged lymph nodes. Some dogs seem to recover but carry the infection silently and later develop a severe chronic form.
- Flea and tick preventionFlea and tick prevention means regularly protecting a pet from these parasites with a product your vet recommends, plus checking the coat and treating the home. Tropical guidelines say dogs and cats in places like India should be protected all year, including indoor pets. Use products licensed for the species, and never put a dog product on a cat.
- FleasFleas are small, wingless, blood-feeding insects. The cat flea, Ctenocephalides felis, is the most common flea on dogs and cats worldwide, and the main flea on dogs studied in India. Fleas cause itching, flea allergy, tapeworm and, in heavy infestations, anaemia in puppies and kittens. Most of the flea life cycle happens in the home.
- FVRCP vaccineFVRCP is the core combined vaccine for cats. It protects against feline viral rhinotracheitis (herpesvirus), calicivirus and panleukopenia. Indian cards often show a brand name from the vial sticker instead, such as Tricat. Kittens start at 6 to 8 weeks, with doses every 2 to 4 weeks until 16 weeks or older, then a booster at about 26 weeks.
Keep exploring
Sources
Each source was opened and read on the date shown. How Petym checks its sources
- Merck Veterinary Manual: Leptospirosis in dogs (opens in a new tab)
- Ministry of Health and Family Welfare: Pre-monsoon leptospirosis advisory (23 June 2026) (opens in a new tab)
- Merck Veterinary Manual: Leptospirosis in dogs (opens in a new tab)
- National Centre for Disease Control: Programme for Prevention and Control of Leptospirosis (opens in a new tab)
- Cornell University College of Veterinary Medicine: Canine leptospirosis (Riney Canine Health Center) (opens in a new tab)
- US Centers for Disease Control and Prevention: Leptospirosis in animals (opens in a new tab)
Show all 13 sourcesShow fewer
- World Health Organization: Leptospirosis: fact sheet (2009) (opens in a new tab)
- ICAR-IVRI: Vaccination of dogs and cats (Hindi leaflet, 2020) (opens in a new tab)
- WSAVA: 2024 guidelines for the vaccination of dogs and cats (WSAVA Vaccination Guidelines Group, Journal of Small Animal Practice) (opens in a new tab)
- ACVIM (Journal of Veterinary Internal Medicine, 2023): Updated ACVIM consensus statement on leptospirosis in dogs (opens in a new tab)
- BMC Infectious Diseases (2026): Leptospirosis and its co-infections in India: prevalence, distribution and clinical implications (opens in a new tab)
- International Journal of Health Geographics (2024): Leptospirosis outbreaks after floods in Kerala (opens in a new tab)
- Journal of Veterinary Medicine (2013), TANUVAS Namakkal: Seroprevalence of leptospiral antibodies in dogs in and around Namakkal (abstract read) (opens in a new tab)