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Leptospirosis in dogs: signs, blood work and testing

Leptospirosis is a bacterial infection spread in the urine of infected animals, often through standing water, mud or wet soil. It can damage the kidneys, liver, lungs and blood clotting. It is also a zoonosis: an infected dog can pass it to people through its urine.

Written by the AI DiagAnimals editorial teamReviewed by the AI DiagAnimals TeamUpdated Our editorial policy

The essentials

The first signs are vague: poor appetite, lethargy, vomiting, thirst and fever. Blood work very often shows a raised creatinine and urea, and sometimes a high bilirubin and low platelets; the urine can contain glucose even though blood glucose is normal. Diagnosis relies on PCR of blood and urine early on, and on two MAT antibody tests a few weeks apart. Wear gloves when handling the dog’s urine.

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The signs

Incubation lasts about 2 to 14 days. Early signs are nonspecific: poor appetite, lethargy, vomiting, increased thirst and urination, fever. The disease can then affect the kidneys (acute kidney injury), the liver (jaundice), the lungs (bleeding into the lungs) and clotting (small bruises, nosebleeds, black stools) [1].

It is not only a disease of farm or hunting dogs: small-breed city dogs, puppies as young as 11 weeks, older dogs and unvaccinated dogs are all affected [1].

What the tests show

Frequencies reported across the studies cited by the 2023 ACVIM consensus statement [1].
FindingHow often it is abnormalTo know
High creatinine55–100%Kidney injury; urea rises too [1].
High bilirubin15–94%Often without other signs of liver failure [1].
Low platelets14–73%Often better within a week of treatment [1].
Glucose in the urine18–83%With normal blood glucose: a sign of damage to the kidney tubules [1].
PotassiumLow or highHigh mainly when the dog produces little or no urine [1].

How to read the creatinine line

Here is an example line from a dog with leptospirosis.

An annotated line from a lab report · Illustrative example
AbbreviationResultUnitLaboratory intervalFlag
CREA Creatinine4.8mg/dL0.5–1.7H
  1. Abbreviation CREA or creatinine.
  2. Result 4.8 mg/dL in this illustrative line: clearly high.
  3. Unit mg/dL in the US; µmol/L elsewhere (mg/dL × 88.4).
  4. Laboratory interval An illustrative dog interval; each laboratory sets its own.
  5. Flag H: above the interval. With a high bilirubin or low platelets, it points towards leptospirosis. In dogs that recover, kidney values often return to normal within 10 to 14 days [1].

Unit converter

Equivalent values

  • Creatinine, µmol/L–
  • Creatinine, mg/L–

Conversion only changes the unit. Compare the result with the interval printed by the laboratory that measured it.

Confirming leptospirosis

  • PCR on blood and urine: useful very early, before antibodies appear. In one study it detected 25% of cases in blood and 69% in urine. Samples are ideally taken before antibiotics [1].
  • MAT antibody test: the reference test uses two samples a few weeks apart. A single titre is conclusive only when very high, because vaccination also raises titres [1].
  • In-clinic rapid tests: convenient, but some also detect vaccine antibodies [1].

Protecting your family

An infected dog sheds the bacteria in its urine. The guidelines recommend gloves when handling urine, protection for pregnant people, and disinfecting soiled surfaces, for example with diluted bleach [1]. A dog that has been treated and sent home poses a low risk [1]. See a doctor if you develop a fever after contact.

Related articles

Urinalysis in dogs and cats

Specific gravity, glucose and protein in the urine.

Read the article

En français : la leptospirose du chien.

Questions to ask your veterinarian

  1. Are the creatinine, urea and bilirubin raised?
  2. Are the platelets low?
  3. Should we run PCR on blood and urine, and a second antibody test?
  4. What precautions should we take at home with the urine?
  5. When will we recheck the kidney values after treatment?
YOUR PET’S FULL REPORT

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Frequently asked questions

What are the first warning signs of leptospirosis?

Poor appetite, lethargy, vomiting, thirst and fever, then sometimes jaundice, bleeding and reduced urine output [1].

Can leptospirosis be cured?

Yes, with antibiotics and supportive care. Kidney values often return to normal in 10 to 14 days, but some dogs are left with chronic kidney disease [1].

Can my dog get Lepto from my backyard?

Yes, if wildlife such as rodents contaminates it with urine. Small city dogs are also affected, not only dogs that roam in the countryside [1].

Is the Lepto vaccine for dogs necessary?

The ACVIM consensus recommends routine vaccination of pet dogs, partly to reduce the risk of transmission to people. Unvaccinated dogs, and dogs vaccinated against only 2 serovars, are among those affected [1].

Can humans catch leptospirosis from dogs?

Yes, through contact with an infected dog’s urine. Dog-to-child transmission has been documented [1].

Sources

  1. Sykes JE et al. Updated ACVIM consensus statement on leptospirosis in dogs. J Vet Intern Med. 2023;37(6):1966-1982. doi.org/10.1111/jvim.16903

Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.

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