Leptospirosis Fact Sheet

How can dogs become infected? 

Just like people, dogs most frequently become infected through exposure to bacteria in the environment e.g. by drinking water contaminated with the urine of rats, for example. Direct contact with the urine or blood from an infected animal can also lead to infection.

What are the clinical signs?

They can vary in severity and are often non-specific signs of illness. Most frequently, dogs will develops malaise, lethargy, reduced appetite and vomiting.  The gums may become icteric. The disease can progress rapidly without treatment and can lead to death in some severe cases. Some dogs will have minimal clinical sign or even be asymptomatic but can still spread the disease to other animals or people.

How will I know if my dog is infected?

If your dog becomes ill with suspicious clinical signs of leptospirosis your vet will run blood tests to check organ function.  They may also check for the presence of bacteria in the blood or urine. They may do serology tests – these are blood tests to see if your dog has antibodies against the infection, however, these may not be present in the acute stages of the disease. Sometimes, a definitive diagnosis cannot be made but if suspicious, your vet may decide to start antibiotics.

Are antibiotics effective at treating the disease?

Yes, there are antibiotics that your vet will use to treat the acute stages of the disease. These may be given intravenously, especially if your pet is vomiting and not eating. Your pet may also require intravenous fluids to support his kidneys. Once his condition improves,  oral antibiotics will be given to clear the infection from the kidneys.

Can the infection be passed to other pets or people in the household?

Yes, although the risk is low you should talk to your vets about testing or treating your other pets. If you develop any clinical signs (e.g. fever or flu like symptoms) contact your GP and inform them of your dog’s diagnosis.

Can I prevent my dog from becoming infected?

We have various effective vaccines in the UK. Some vaccines contain two strains of the organisms (L2 vaccines) and other contain four (L4 vaccines). L4 vaccines provide protection to a wider range or Leptospira organisms and we advise use of these vaccines, particularly if you travel abroad with your dog (where different strains of Leptospira are found).

I have read a lot about reactions to Leptospira vaccines – do I need to vaccinate my dog?  We live in an urban environment and my dog does not come in contact with water.

The overall incidence of suspected adverse reactions to both L2 and L4 vaccine products is considered to be rare (according to data from the VMD, the body which gathers all reports of adverse reaction from veterinary surgeons). Their published data show fewer than two adverse reactions for L2, and fewer than seven for L4, for every 10,000 vaccine doses sold.

We would strongly advise that your dog is vaccinated every year for Leptospira even if you live in an urban area as every dog is at risk of exposure. There are exceptional circumstances where a dog does not leave the home environment; even in these cases, gardens can be contaminated from wildlife entering the premises.

We are in lockdown and my dog has missed his booster; should I be worried?

We are not sure how long immunity lasts after vaccination but it is likely to be less than 18 months in the case of Leptospira. For this reason, we advise yearly boosters. If your dog is not able to receive a booster in time then you should try to minimise risk of exposure (i.e. do not take your pet out swimming, discourage drinking from puddles, do not go to busy parks and minimise contact with other dogs or wildlife).

Can cats become infected?

Yes, but it is very rare for them to develop clinical disease. It is possible that they could play a role in spreading the disease through urine but this is not well established.