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Leptospirosis in dogs

isolated dog


  • Leptospirosis is a nasty disease caused by bacteria.
  • It causes damage to the liver and kidneys and is, sadly, often fatal.
  • Leptospirosis spreads via other infected dogs, mice, rats and cows and can also be caught from infected water.
  • Your dog is at higher risk of catching leptospirosis if they regularly kill rodents, live on a farm or spend a lot of time in water.
  • Leptospirosis can infect people and is commonly known as Weil’s disease.
  • Fortunately, we can vaccinate against leptospirosis – keep your dog protected with regular boosters.

What is Leptospirosis?

Leptospirosis (often shortened to lepto) is an infectious disease caused by bacteria. Dogs can catch lepto by coming into contact with urine from an infected animal or from contaminated water. Rats can carry lepto and are a particular risk for dogs that like hunting and spending time in water. Lepto is a serious, often fatal disease that damages the liver and kidneys. Leptospirosis can also pass to people and make them very poorly.

There are a group of bacteria that cause lepto – each one slightly different. We vaccinate pet dogs against the types of lepto most commonly found in the UK.


If your dog catches lepto, their symptoms will depend on how much immunity (protection) they have, which lepto bacteria they have caught, and which organs it attacks. Symptoms can include:


Lepto bacteria enter the body through the mouth, nose, or wounds. Once inside the body lepto attacks vital organs, particularly the liver and kidneys.


If your dog has a mild case of lepto, your vet may use antibiotics, a fluid drip and other medicines to help fight the disease. In more severe cases, symptoms often start suddenly, cause serious illness and sometimes death. If your dog has a severe form of lepto, you may need to consider putting them to sleep to stop them suffering.

Dogs with lepto must be treated in isolation so that they don’t pass the disease on to other pets or hospital staff. Even after they’ve recovered, dogs can keep spreading lepto germs in their urine and remain a risk to other pets and people for some time.


Lepto is a very serious disease that, sadly, many dogs don’t recover from.

When to contact your vet

Contact your vet for an appointment if you see any symptoms of lepto in your dog, particularly if they’ve never been vaccinated or have missed any booster shots. Your dog is at higher risk of catching lepto if they regularly kill rodents, live on a farm or spend a lot of time in water.

You know your dog best, if they don’t have the symptoms listed above but you are still concerned, always contact your vet.


Vaccinating every year will give your dog protection from lepto and helps to keep your family and other pets safe. Because there are a few different types of lepto bacteria that cause disease, there are a few different lepto vaccinations available. Speak to your vet about which lepto vaccination will give your dog the best protection.


Treatment for a dog with leptospirosis is likely to be expensive and unexpected. Consider insuring your dog as soon as you get them, before any signs of illness start. This will ensure you have all the support you need to care for them.

It’s also very important to speak openly to your vet about your finances, the cost of treatment, as well as what you think is best for your dog.

Published: June 2019

PetWise Pet Health Hub – brought to you thanks to support from players of People’s Postcode Lottery 

Written by vets and vet nurses. This advice is for UK pets only.

Illustrations by Samantha Elmhurst