Leptospirosis

What is leptospirosis?

Leptospirosis is a disease caused by Leptospira bacteria, which attack the kidneys and liver. The bacteria are shed in the urine of infected animals — especially rats, raccoons, skunks, and opossums — and can survive for weeks to months in moist soil, puddles, and standing water.

Leptospirosis is also zoonotic, meaning it can spread from animals to people.

How could my dog be exposed?

A dog does not need to roam to encounter leptospirosis. Common routes of exposure include:

• Drinking from or wading through puddles, gutters, or standing water
• Sniffing or licking ground where wildlife or rodents have urinated
• Stepping in contaminated urine, then licking their paws
• Contact with rats and other wildlife drawn to yards, garages, and trash areas

Even small dogs that live mostly indoors are at risk — a brief potty walk past a spot where rats have urinated can be enough.

What are the signs?

Signs vary widely, and some dogs show very few early on. Watch for:

• Fever, lethargy, and loss of appetite
• Vomiting or diarrhea
• Increased thirst and urination — or, in severe cases, very little urine
• Muscle soreness, stiffness, or reluctance to move
• Yellowing of the eyes, gums, or skin (jaundice)

Untreated, leptospirosis can progress to kidney failure, liver failure, or both.

How is it diagnosed and treated?

Diagnosis typically combines blood and urine testing — bloodwork to assess kidney and liver function, plus specific antibody or DNA (PCR) tests for the bacteria. Because early signs are vague, testing is often run when an otherwise unexplained kidney or liver problem appears.

Treatment centers on antibiotics and supportive care. Milder cases may be managed with oral antibiotics at home, while sicker dogs need hospitalization with intravenous fluids. Dogs treated early usually recover well; advanced kidney or liver damage carries a more guarded outlook.

A note for the humans in the house: while your dog is being treated, avoid contact with their urine, wear gloves when cleaning accidents, wash hands thoroughly, and let your physician know your dog has leptospirosis if anyone in the home develops flu-like symptoms.

How can I prevent it?

Vaccination is the most reliable protection. The leptospirosis vaccine covers the most common bacterial strains and is given as an initial two-dose series followed by an annual booster. We recommend it for most dogs, including small and primarily indoor dogs.

At home, discourage drinking from puddles and standing water, secure trash to avoid attracting rodents and wildlife, and address rat activity around your home promptly. If your dog develops fever, vomiting, or unusual thirst, have them seen promptly — early treatment makes a real difference.