Dog Leptospirosis: Kidney and Liver Warning Signs

Leptospirosis is a potentially fatal bacterial infection that attacks the kidneys and liver in dogs — and it can spread to humans. Early signs are easily confused with a minor illness, but rapid deterioration can follow within days if treatment is not started promptly.

Last reviewed: June 2026

What Is Leptospirosis and How Do Dogs Get It?

Leptospirosis is caused by spirochete bacteria of the genus Leptospira, transmitted through the urine of infected wildlife — most commonly raccoons, rats, opossums, deer, and skunks. Dogs typically become infected by:

• Drinking from or swimming in contaminated water (puddles, ponds, streams, or flooded areas where infected wildlife have urinated)
• Direct contact with infected soil or mud, particularly in wet environments
• Contact with infected urine from other dogs or wildlife

The bacteria enter through mucous membranes (mouth, nose, eyes) or broken skin. After infection, leptospires spread through the bloodstream and localize primarily in the kidneys and liver, where they cause acute inflammation and cell death. Leptospirosis is a zoonotic disease — it can spread from dogs to humans through contact with infected urine or tissues.

Geographic risk is highest in warm, humid climates and after heavy rainfall or flooding, but cases occur throughout North America. Urban dogs with access to rodent-contaminated areas and rural dogs with wildlife exposure are both at significant risk. As described in Greene's Infectious Diseases of the Dog and Cat, the serovars most commonly identified in North American clinical cases include L. pomona, L. grippotyphosa, L. canicola, and L. icterohaemorrhagiae.

Kidney and Liver Warning Signs

Leptospirosis produces a spectrum of disease severity. Mild or subclinical infections occur but are not recognized; clinically affected dogs typically develop signs within 5–14 days of infection:

Early signs (first 1–3 days) — easy to miss:

• Sudden fever, lethargy, and loss of appetite
• Muscle pain and reluctance to move — dogs may seem stiff or sore
• Vomiting (often the first noticed sign)
• Shivering

Kidney damage signs (acute kidney injury — AKI):

• Decreased urination or no urination at all (oliguria/anuria) — kidney failure causing urine production to drop
• OR — paradoxically — markedly increased urination in the early phase as kidneys lose concentrating ability
• Painful or swollen kidneys — the dog may resist being touched over the back/flanks
• Increased thirst followed by decreased intake as nausea worsens
• Oral ulcers in severe uremia

Liver damage signs (hepatitis/jaundice):

• Yellow tint to the whites of the eyes, gums, or skin (icterus/jaundice)
• Orange-tinged urine
• Vomiting and diarrhea
• Abdominal pain — the dog may be reluctant to lie down or cry when the abdomen is touched
• Bleeding tendencies — bruising, bloody vomit or stools, petechiae (tiny red dots) on skin or gums

Signs of severe or fatal disease:

• Respiratory distress — leptospirosis can cause severe pulmonary hemorrhage, a rapidly fatal complication
• Bleeding from nose, gums, or skin
• Collapse and shock

Any dog with acute vomiting, fever, and increased thirst following recent outdoor activity in high-risk environments should have leptospirosis included in the differential — especially if jaundice or decreased urine output develops (AAHA Canine Vaccination Guidelines, 2022).

Diagnosis

Leptospirosis mimics other causes of acute kidney injury and hepatitis, making specific testing essential:

• Serology (MAT — microscopic agglutination test) — the gold standard for diagnosis; requires paired samples (acute and convalescent 2–4 weeks apart) for definitive interpretation; a single high titer (≥1:800) in a sick, unvaccinated dog is strongly suggestive
• PCR (blood and urine) — detects bacterial DNA directly; most sensitive in the first week of illness before antibiotics; preferred for early rapid diagnosis
• Chemistry panel — elevated BUN, creatinine (kidney damage), elevated ALT and bilirubin (liver damage); these findings prompt immediate supportive care even before serology results return
• Complete blood count — thrombocytopenia (low platelets), leukocytosis; thrombocytopenia raises bleeding risk
• Urinalysis — protein, casts, blood; urine sediment shows active renal tubular damage

Treatment and Prognosis

Leptospirosis is treatable if caught early. Treatment has two components:

Antibiotic therapy:

• Doxycycline — the drug of choice for treating leptospirosis and eliminating the carrier state; started as soon as the diagnosis is suspected, before confirmation
• Ampicillin or penicillin — used in hospital for the first phase if doxycycline cannot be given orally (vomiting dogs)

Supportive care (often requires hospitalization):

• IV fluid therapy — critical for flushing kidneys, maintaining hydration, and correcting electrolyte abnormalities; $200–500 per day
• Anti-nausea medications — maropitant, ondansetron
• Nutritional support — feeding tubes if vomiting persists
• Dialysis — for severe, dialysis-requiring AKI at specialty centers

Dogs that receive early treatment often recover full or near-full kidney and liver function. Dogs with severe AKI requiring dialysis have variable outcomes — some recover, others progress to permanent kidney disease. Pulmonary hemorrhage syndrome (LPHS), when it occurs, carries a poor prognosis.

Infection control: dogs being treated for leptospirosis shed bacteria in urine. Hospital staff handle these patients with protective equipment, and owners should avoid contact with urine without gloves. Household members should notify their physician if the dog is diagnosed with leptospirosis.

As noted in the AAHA Canine Vaccination Guidelines, 2022, the quadrivalent leptospirosis vaccine is classified as a non-core vaccine recommended based on geographic risk and lifestyle. Dogs with outdoor exposure to wildlife or water sources should discuss vaccination with their veterinarian.

When to See a Vet

Call your vet today if:

• Your dog has sudden fever, lethargy, and vomiting following outdoor activity
• Your dog is drinking and urinating dramatically more than usual, or suddenly very little
• You notice yellow tint to the eyes or gums
• Your dog is muscle-sore or reluctant to move after a hike near water

Go to the ER immediately if:

• Your dog has not urinated in more than 12 hours
• Your dog is vomiting blood or has bloody diarrhea
• Your dog is breathing rapidly or with difficulty — possible pulmonary hemorrhage
• Gums are pale, yellow, or your dog collapses
• Known leptospirosis exposure and rapid deterioration occurs

Frequently Asked Questions

Can humans get leptospirosis from an infected dog? Yes — leptospirosis is a zoonotic disease. Humans can become infected through contact with infected dog urine or tissues, particularly via mucous membranes or cuts in the skin. People in contact with a dog diagnosed with leptospirosis should use gloves when handling the dog, avoid contact with urine, wash hands thoroughly, and notify their physician about the exposure. The human illness (Weil's disease in severe cases) can involve kidney failure and liver disease.

Is the leptospirosis vaccine effective? The current 4-serovar leptospirosis vaccines provide good protection against the most common disease-causing serovars in North America. Vaccinated dogs that are infected may develop milder illness than unvaccinated dogs. The vaccine does not protect against all serovars, but it significantly reduces risk in dogs with outdoor exposure. Annual booster vaccination is required to maintain protective immunity per the AAHA Canine Vaccination Guidelines, 2022.

How much does treating leptospirosis cost? Initial workup including exam, chemistry panel, CBC, urinalysis, and leptospirosis PCR or serology runs $400–900. Hospitalization with IV fluids, antibiotics, and supportive care typically costs $1,000–3,000 for moderate cases over 3–5 days. Severe cases requiring dialysis at a specialty internal medicine facility cost $3,000–8,000 or more. Dogs that recover from AKI may require long-term kidney disease monitoring and management.

What environments put dogs at highest risk for leptospirosis? Highest-risk environments include ponds, rivers, and streams — especially slow-moving or stagnant water frequented by wildlife; muddy terrain after rainfall; areas with known rodent activity (farms, urban alleys, construction sites); and regions with recent flooding. Rural dogs, hunting dogs, and sporting dogs that frequent these environments are at highest risk. Urban dogs in rodent-dense environments are also at meaningful risk.

Can leptospirosis cause permanent kidney damage in dogs? Yes. While many dogs that receive early treatment recover full kidney function, dogs that develop severe acute kidney injury — especially those requiring dialysis — have a higher risk of chronic kidney disease (CKD) as a sequela. Regular kidney function monitoring (chemistry panel with BUN and creatinine) every 3–6 months is recommended for at least a year after leptospirosis recovery to detect any developing CKD.

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