Leptospirosis in dogs


  • Leptospirosis is a disease caused by bacteria that damage vital organs such as the liver and kidneys.
  • Leptospirosis is very serious disease, that is sadly, often fatal.
  • Leptospirosis is spread by infected dogs, mice, rats and cows but can also be caught from infected water.
  • Your dog is at higher risk of catching leptospirosis if they live on a farm, regularly kill rodents, or spend a lot of time swimming.
  • Leptospirosis can infect humans and is commonly known as Weil’s disease.
  • Protect your dog by vaccinating them against leptospirosis.

What is Leptospirosis?

Leptospirosis (often shortened to lepto), is a bacterial disease that causes serious illness by damaging vital organs such as the liver and kidneys. Leptospirosis bacteria can spread in urine, and can enter the body through the mouth, nose or wounds.

Dogs can catch leptospirosis from:

  • Another infected dog
  • Sniffing/licking the ground where an infected dog has urinated
  • Urine from an infected cow, pig or rodent (i.e. if they spend a lot of time on farms)
  • Infected wet ground or fresh water (rivers / lakes) - lepto can live in wet ground and freshwater for several months.

There are a few different types of leptospirosis bacteria and each one is slightly different.

Fortunately, we can vaccinate against the types of lepto bacteria commonly found in the UK.

Can humans get lepto from dogs?

Leptospirosis can pass to humans cause serious illness. Lepto in people is also known as Weil’s disease. If you have concerns that you or someone you know may have leptospirosis, it is best to contact your doctor or the NHS for advice.


Symptoms of lepto vary a lot but can include:

When to contact your vet

Contact your vet if you see any symptoms of lepto in your dog, especially if they aren’t up to date with their vaccinations. 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.


If your dog has a mild case of lepto, your vet may be able to use antibiotics, a fluid drip and other medicines to help fight the disease. Sadly, if your dog becomes seriously ill with leptospirosis, you may need to consider putting them to sleep to stop them suffering.

Dogs with lepto must be treated in isolation to prevent them spreading it to other pets or hospital staff. Even after they’ve recovered, dogs with lepto can keep spreading the bacteria in their urine and remain a risk to other pets and people for some time.


Leptospirosis is a very serious disease. Some dogs with mild symptoms, recover if they get veterinary help quickly, but dogs with more severe symptoms often die during the early stages of the disease or become so poorly that they need to be put to sleep (even with veterinary treatment).


Fortunately, we can vaccinate against leptospirosis. There are a few different types of leptospirosis bacteria, so there are there are several different lepto vaccinations available. Speak to your vet about which lepto vaccination will give your dog the best protection. Vaccinate your dog against leptospirosis every year.

Taking an unvaccinated puppy outside

An unvaccinated puppy, or a puppy that has only had their first injection has no protection against leptospirosis or the other diseases we vaccinate against. Your puppy will be safe to go out for a walk and meet other dogs 1-2 weeks after they complete their first vaccination course. Until then:

  • Home and garden. Your puppy is safe to go into your garden as long as no unvaccinated dogs have visited recently.
  • Public places. You can take your puppy out into public but make sure you carry them and don’t put them on the ground.
  • Farms and fresh water. It’s especially important to avoid farms and fresh water until your puppy is fully protected from leptospirosis.
  • Puppy classes. As long as your puppy is healthy, it’s okay to enrol them in a puppy class. The benefits far outweigh the very small risk of catching distemper from another puppy.


Treatment for a dog with leptospirosis is likely to be expensive and unexpected. It’s 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.

Consider taking out dog insurance as soon as you bring your dog home, before any signs of illness start. This will give you peace of mind that you have some financial support if they ever become unwell. 

Published: April 2020

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