Leptospirosis is a bacterial infection dogs can contract from contaminated water, soil, or wildlife urine. It can cause acute kidney and liver failure — and it is one of the few serious dog diseases that can also spread to humans.
Last reviewed: June 2026
What Is Leptospirosis in Dogs?
Leptospirosis is caused by Leptospira bacteria, which survive in standing water, mud, and moist soil — especially in warm climates or after heavy rain. Dogs are infected by contact with contaminated water or the urine of infected wildlife (raccoons, skunks, deer, rats). The bacteria enter through mucous membranes, eyes, or small skin abrasions.
Leptospirosis can cause a spectrum of illness from subclinical infection to acute renal and hepatic failure and pulmonary hemorrhage syndrome. The serovars most commonly affecting US dogs include Canicola, Icterohaemorrhagiae, Grippotyphosa, and Pomona. As described in Greene's Infectious Diseases of the Dog and Cat, clinical disease often appears 5–14 days after exposure.
Any dog can be infected, but outdoor dogs, hunting dogs, dogs near wildlife habitat, and dogs in flood-prone areas face higher risk. Approximately 1,000–1,500 cases of canine leptospirosis are confirmed annually in the US, though the true number is substantially higher given underdiagnosis.
Signs of Leptospirosis in Dogs
Early signs (days 1–5):
- Sudden fever (103–104°F / 39.4–40°C), shivering
- Muscle pain — reluctance to move, arched back, sensitivity to touch
- Lethargy, anorexia
- Vomiting, diarrhea (sometimes bloody)
As the disease progresses (acute kidney/liver involvement):
- Markedly increased or decreased urination (renal dysfunction)
- Jaundice — yellow-tinged whites of the eyes, gums, or skin (hepatic involvement)
- Abdominal pain — hunched posture, reluctance to have belly touched
- Dehydration, sunken eyes, dry gums
- Vomiting worsening
Severe/late disease:
- Oliguria or anuria (little or no urine — severe acute kidney injury)
- Hemorrhage — bloody urine, nosebleed, coughing blood (rare but serious)
- Collapse, respiratory distress (pulmonary hemorrhage syndrome — rapidly fatal)
The AAHA Canine Vaccination Guidelines, 2022 classify leptospirosis vaccination as "lifestyle-based" — recommended for dogs with outdoor or water exposure, not universally required.
Diagnosis and Treatment
Diagnosis requires specific testing: MAT (microscopic agglutination test) — the gold standard — or PCR on blood/urine (best in the acute phase, before antibiotics). Standard blood chemistry shows elevated creatinine/BUN (kidney) and elevated liver enzymes. Urinalysis reveals casts, protein, and sometimes renal tubular cells.
Treatment:
- IV fluids — the cornerstone of acute renal failure management; most dogs require 1–5 days of hospitalization
- Antibiotics: initial doxycycline or ampicillin to eliminate bacteremia; doxycycline for a full 14-day oral course to eliminate renal shedding
- Supportive care: anti-nausea medications, appetite stimulants, electrolyte management
Most dogs with mild-to-moderate disease recover fully with prompt treatment. Dogs with severe acute kidney injury may require dialysis at a specialty center. Overall mortality in treated dogs is approximately 5–15%; severe pulmonary involvement carries much higher mortality.
Treatment costs: emergency hospitalization runs $800–2,500 for typical cases; severe kidney or liver failure requiring intensive care can cost $3,000–7,000 or more.
Preventing Leptospirosis
The 4-serovar leptospirosis vaccine effectively reduces the risk of disease from the most common infecting strains. It requires an initial 2-dose series and annual boosters. As noted in the AAHA Canine Vaccination Guidelines, 2022, dogs with outdoor exposure, water access, or wildlife contact should receive leptospirosis vaccination.
Additional prevention: avoid letting dogs drink from ponds, puddles, or standing water; reduce wildlife food sources around the home.
Zoonotic Risk
Leptospirosis is a significant zoonotic disease — infected dogs can shed bacteria in urine for weeks. Use gloves when handling urine from a suspected leptospirosis dog; wash hands thoroughly; avoid contact between dog urine and open skin wounds or mucous membranes. The risk of human infection from a treated household dog is low but not zero.
When to See a Vet
Call your vet today if:
- Your dog has sudden fever, muscle soreness, and is not eating after outdoor water exposure
- You notice jaundice (yellow tinge to eyes or gums) combined with lethargy
- Your dog is vomiting repeatedly and seems painful when touched on the abdomen
- Your dog's urination pattern has changed dramatically (much more or much less)
Go to the ER immediately if:
- Your dog is collapsed, extremely weak, or unresponsive
- You see bloody urine, bloody stool, or your dog is coughing up blood
- Your dog is not urinating at all (anuria — a kidney emergency)
- Difficulty breathing develops in combination with the above signs
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Frequently Asked Questions
Is leptospirosis contagious from dogs to humans? Yes — leptospirosis is a zoonotic disease. Infected dogs shed bacteria in urine. Human infection occurs through contact with infected urine or contaminated water. Wear gloves when cleaning up after a leptospirosis-positive dog and wash hands thoroughly. Seek medical attention if you develop flu-like symptoms after exposure.
How much does leptospirosis treatment cost for a dog? Hospitalization for typical leptospirosis with IV fluids, antibiotics, and supportive care runs $800–2,500. Severe cases with acute kidney injury, dialysis needs, or pulmonary involvement can cost $3,000–7,000 or more. Early treatment dramatically improves outcomes and reduces total cost.
Should my dog be vaccinated against leptospirosis? Leptospirosis vaccine is recommended for dogs with outdoor exposure, water access, or wildlife contact. It requires a 2-dose initial series and annual boosters. The vaccine protects against the 4 most common US serovars. Discuss with your vet whether your dog's lifestyle makes vaccination appropriate.
Can leptospirosis cause permanent kidney damage? Yes — dogs that survive severe acute kidney injury may have residual chronic kidney disease. The degree of permanent damage depends on how early treatment was started and how severe the initial injury was. Most dogs treated promptly recover normal or near-normal kidney function.
What water sources are most dangerous for leptospirosis? Standing water, puddles, ponds, slow-moving streams, and flooded areas are highest risk — especially in warm, humid climates or after heavy rain. Leptospira bacteria survive longest in warm, wet environments and are spread through infected wildlife urine draining into these water sources.
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