Leptospirosis in Dogs

Written by Shula Berg BVSc CertAVP(GSAS) GPAdvCert(SASTS) MRCVS
Clinically reviewed by Elizabeth McLennan-Green BVM&S CertAVP(SAM) MRCVS

Table of Contents

- Overview
- Symptoms
- Diagnosis
- Treatment
- Outlook

What is Leptospirosis?

Leptospirosis refers to the clinical condition caused by infection with bacteria called Leptospira. Many different strains of the bacteria exist and several cause clinical diseases in dogs. Routine vaccination against leptospirosis is recommended for all dogs, however vaccines only protect against 2-4 different strains, depending on the brand. For this reason, even vaccinated animals can contract leptospirosis, although the risk is much lower than if no vaccines have been given. 

Leptospira bacteria can infect almost all mammals, including wildlife and people. Some animals, such as rats, do not become unwell but can remain infected for years. Bacteria is often shed in the urine of infected animals and new animals obtain infection from direct contact or environmental contamination. Leptospirosis occurs all over the world and, in some areas, is a significant cause of disease in people. 

What are the symptoms of Leptospirosis?

Leptospirosis can cause a wide variety of problems, often making it challenging to diagnose.  

The most common symptoms are: 

  • Lethargy  
  • Loss of appetite 
  • Vomiting 
  • Abdominal pain and increased thirst due to acute kidney failure 
  • Liver disease, which has very similar symptoms to kidney failure 
  • Jaundice (yellow colour of the eyes, mucous membranes and skin) 

Less common symptoms include: 

  • Muscle inflammation (seen as pain, stiffness and weakness) 
  • Bleeding disorders (seen as bruising or blood in vomit) 
  • Uveitis (seen as painful eyes) 
  • Coughing 
  • Diarrhoea 
  • Fever 
  • Discharge from the eyes and nose 
  • Swollen lymph nodes 

Which tests are used to diagnose Leptospirosis?

Any dog can contract leptospirosis, but it is generally considered more likely in dogs who are unvaccinated, or who spend a large amount of time in high-risk areas (such as farmland), or dogs used for shooting. 

Due to the wide variety of symptoms, suspicion of leptospirosis often occurs after blood work is performed. This commonly shows elevation of two markers, known as, urea and creatinine, which show kidney function. This may be accompanied by elevation of liver enzymes or reduced platelet count. 

Several lab tests are available to detect the Leptospira bacteria. None are perfect as some can give a false positive in a vaccinated dog, while others will only read positive if the dog is actively shedding bacteria. It is always recommended to try and confirm the diagnosis, but treatment is often started before the results are available.

How is Leptospirosis treated?

Dogs with leptospirosis need intensive care and will usually need to stay at the vets for several days.  Due to the infectious nature of the virus, patients will typically be housed in an isolation unit. Referral to a practice with suitable facilities may be advised. During the time they are hospitalised, all staff dealing with the dog will be required to wear personal protective equipment (PPE). This is to prevent transmission of the bacteria to people. Leptospira bacteria are killed by most household disinfectants and the home should be thoroughly cleaned before the dog is discharged. 

Treatment of leptospirosis consists of antibiotics to kill the bacteria with supportive care to help the body fight the infection. Typically, this involves: 


A specific antibiotic, doxycycline, is used to treat leptospirosis. This is most often a tablet, so patients who are too unwell to keep oral medication down may be started on intravenous penicillin as well. Antibiotics need to be given for at least 2 weeks, even if the dog seems better. 

Fluid therapy (drip) 

Dogs with leptospirosis can lose large amounts of fluid in vomit or diarrhoea. A drip is used to prevent dehydration and keep blood pressure stable; low blood pressure will cause further damage to the kidneys. 

Assisted nutrition 

Some dogs don’t want to eat but require energy to fight infection. Assisted nutrition can be provided by mouth, or straight into the stomach via a feeding tube.

Other medications 

Dogs with leptospirosis may be given anti-nausea drugs, pain relief, gastro-protectants and liver support. Other treatment will depend on the symptoms of the disease. 

Commonly, dogs will have a urinary catheter placed. This allows urine production to be monitored (as this is an indicator of kidney function) as well as making it easier to prevent contamination of surroundings with infectious urine.

Blood tests may be repeated regularly to monitor for improvement in kidney and/or liver levels, and to check electrolytes and blood glucose. 

What is the outlook for dogs with Leptospirosis?

Due to the wide variety of ways in which leptospirosis can manifest, prognosis can vary. For dogs with severe kidney or liver failure, the outcome is often poor as many patients don’t survive. This is also the case for dogs who have multiple symptoms, especially less common symptoms, such as bleeding disorders. For those who do recover, kidney damage can be permanent and cause chronic renal failure.

Dogs who improve rapidly, and recover without long-term damage, have an excellent prognosis.

Essential annual vaccinations are included in The Healthy Pet Club membership.


Please note that the content made available on this webpage is for general information purposes only. Whilst we try to ensure that at the time of writing all material is up to date and reflects industry standards, we make no representation, warranties or guarantees that the information made available is up to date, accurate or complete. Any reliance placed by yourselves is done so at your own risk.

Page last reviewed: 7th August 2023
Next review due: 7th August 2025

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