Leptospirosis
Also called Weil's disease, Lepto
A bacterial disease spread in the urine of infected animals, mainly rats and livestock. It can cause kidney and liver failure and bleeding in dogs, and abortion in cattle and pigs. People can catch it too.
Cause and spread
- Cause
- Bacteria of the genus Leptospira, with many types (serovars) adapted to different animals.
- How it spreads
- Through urine of carrier animals, directly or through water and soil. The bacteria enter through the lining of the mouth, eyes and nose and through broken or long-soaked skin.
- People
- People are infected through contact with urine, contaminated water or tissue from infected animals. Wear gloves and boots, and wash hands.
Signs to watch for
- Dogs: fever, depression, vomiting, stiffness and muscle pain
- Dogs: increased thirst and urination, kidney failure, jaundice and bleeding
- Cattle and pigs: abortion, stillbirth and weak young
- Calves: fever, jaundice and red urine
- Many infections cause mild or no signs
Many diseases look alike. Only a laboratory test can tell them apart, so please see a veterinarian for any sick animal.
How it is diagnosed
The bacteria or their genes are looked for in blood in acute infection, and in urine, milk or tissue. PCR is widely used. Antibody tests are also used but need careful reading: vaccination, early illness and chronic infection can all change the result, so pairs of samples are preferred.
- Usually the first testLeptospirosis IgM Rapid TestA quick antibody test for recent infection in dogs.
- Confirms the diseaseLeptospirosis PCRDetects Leptospira genes in blood or urine.
- Supports the diagnosisKidney Function Test (KFT) - BasicShows kidney damage.
- Supports the diagnosisLiver Function Test (LFT) - BasicShows liver damage.
- Supports the diagnosisComplete Blood Count (CBC)Shows anaemia and infection.
Prevention and control
- Vaccinate dogs against the types common in your area; ask your veterinarian
- Control rats and mice
- Avoid letting animals drink from or swim in stagnant water that may be contaminated
- Wear protective clothing when handling aborted tissue or urine
Where this information comes from
- Leptospirosis (factsheet) · Center for Food Security and Public Health, Iowa State University
General information for animal owners and veterinarians, last checked October 2026. It does not replace the advice of your veterinarian, who should decide which tests and treatment your animal needs.