Brucellosis in Dogs


  • Canine brucellosis is an infectious disease in dogs, caused by a bacteria called ‘Brucella canis’.
  • In dogs, it mainly affects the reproductive organs (womb and testicles), causing infertility and abortion, but can also travel to the joints and spine, causing severe lameness and back pain.
  • Until recently, the UK has been free from canine brucellosis but, unfortunately, it’s common in other countries around the world.
  • Vets are seeing an increase in cases due to the rise in dogs being imported and travelling outside the UK.
  • Canine brucellosis is zoonotic, meaning it can also cause illness in humans.
  • It’s important that we control the spread of canine brucellosis to protect both human and animal health.

What is Canine brucellosis?

Canine brucellosis is an infectious disease that affects dogs and is caused by a bacteria called Brucella canis. It mainly affects the reproductive organs (womb and testicles) causing infertility and abortion, but in some dogs it also travels to their joints and spine, causing severe lameness and back pain. Brucella canis can also cause illness in people who have been in contact with infected dogs but, fortunately, this is very rare.

How do dogs catch brucellosis?

Brucella canis travels in semen (sperm), vaginal discharge and birthing/abortion fluids. It also travels in urine, saliva and snot, but in much lower numbers, so these fluids are much less infectious. The most common way for a dog to catch brucellosis is by:

  • Mating with an infected dog.
  • Licking/eating infected birthing/abortion fluids from an infected dog – once an infected dog has given birth or aborted, she will continue to shed large amounts of Brucella bacteria in her vaginal fluids/discharge for 4-6 weeks.
  • Sniffing or licking the genitals of an infected dog, especially female dogs in season.
  • Puppies can catch it in the womb or through contaminated milk if their mother is infected.
  • It is possible for a dog to catch brucellosis from infected urine, saliva or snot, but this is much less common.

How common is brucellosis?

Until very recently the UK has been free from Brucella canis but, unfortunately, it’s endemic (common) in certain parts of Eastern Europe, Asia, Africa and the Americas. Although case numbers are still low in the UK, since 2020 there has been a significant increase in reported cases due to the rise in dogs being imported into the UK, and pet dogs travelling out of the UK with their owners.


Most dogs don’t show any symptoms for months to years after catching brucellosis, but during this time they can be infectious to other dogs and people. Most dogs become poorly at some point and develop symptoms such as:

  • Abortion (usually between day 45-59 of pregnancy)
  • Stillbirth
  • Infertility (not able to get pregnant)
  • Swollen testicles (males)
  • Irritation of the skin around the testicles (males)
  • Infected womb (females)
  • Ongoing vaginal discharge
  • Severe lameness and back pain
  • Swollen lymph nodes
  • A high temperature
  • Weight loss
  • Low energy (lethargy)
  • Eye problems


Brucellosis can be diagnosed with a blood test - there are a few different tests available and your vet may want to run more than one to be sure of the result. If there is a strong chance your dog could have brucellosis, you will need to confine them to your home and garden, away from all other dogs and public spaces while you wait for their results. We also recommend doing this for imported dogs that are awaiting test results.   

After a dog is exposed to brucellosis it can take up to 16 weeks for it to show up in a blood sample, so if it’s been less than that since your dog was at risk, they will need to be retested after 16 weeks.

If your dog is diagnosed with brucellosis, it must be reported to ‘The Animal and Plant Health Agency (APHA)’ by law.


Unfortunately, brucellosis in dogs can’t be cured. Antibiotics can be used to reduce the amount of Brucella bacteria in their body but won’t get rid of all of them. This means that once a dog is infected, they are always infected, and can be infectious to other dogs and people. Even if they don’t have symptoms at the time of diagnosis, they are very likely to become poorly with brucellosis at some point. Sadly, the only way to prevent your dog from suffering with brucellosis, or spreading it to other dogs and people, is to put them to sleep.

If you decide against putting your dog to sleep, you will need to:

  • Keep them away from all other dogs, people and public spaces for the rest of their life – to prevent them from spreading it.
  • Wear gloves, eye protection and a facemask when you clean up their urine or faeces, and wash your hands properly afterwards.
  • Avoid any contact with any discharge from their vagina/penis.
  • Never breed them and have them neutered at a clinic that can do it safely.
  • Give them several, long courses of antibiotics.
  • Have their Brucella antibody levels checked regularly. If levels are rising, this means that their brucellosis is getting worse. If they continue to rise despite a course of antibiotics, you will need to consider putting your dog to sleep before they start to suffer.

None of these measures will cure your dog of brucellosis, and it’s important to consider this decision very carefully. Treatment costs will be high, they will always be an infection risk to you and any other dogs or people they come into contact with, and they are likely to become very unhappy being restricted to just your home and garden.

When to contact your vet

It’s important to contact your vet for advice if:

  • You are considering importing a dog.
  • You own an imported dog that’s never been tested for brucellosis.
  • Your dog has been in contact with a dog with brucellosis.
  • Your dog is showing symptoms of brucellosis, especially if they’re imported or have travelled outside of the UK.

Due to limited charitable resources, PDSA is unable to offer brucellosis screening unless your dog is unwell and highly suspected to have the disease. We recommend contacting a private veterinary practice for routine screening of at-risk dogs.

How do humans catch brucellosis?

The most common way for humans to catch brucellosis is if they come into contact with the birthing fluid, or abortion matter from an infected dog. This includes their vaginal discharge, which remains extremely infectious for 4-6 weeks after giving birth or aborting. People in regular contact with imported dogs, vets and vet nurses, and lab staff that handle bodily fluids are at the highest risk of being exposed. Fortunately, the risk to the general public is extremely low.

What are the symptoms of brucellosis in humans?

Brucellosis usually causes vague flu-like symptoms in humans, such as high temperature, swollen glands, headaches, back pain and generally feeling unwell. However, it can be much more serious in children under five, pregnant women and people with weak immune systems. Symptoms tend to take between a few weeks to several years to develop, can last a long time, or come and go. Fortunately, brucellosis in humans is very rare and unlike in dogs, it is treatable. If you are concerned that you have been exposed to brucellosis, contact your doctor for advice.


Should all imported dogs be screened for brucellosis before entering the UK?

Yes, we strongly recommend that any dog entering the UK from another country is screened for brucellosis before they travel. If you are considering importing a dog from abroad, speak to your vet for advice about testing, and make sure the dog is confirmed negative before they enter the UK. Unfortunately, PDSA is unable to offer brucellosis screening as part of its charitable service.

Is there a vaccine for brucellosis in dogs?

Unfortunately, there isn’t yet a vaccine for brucellosis in dogs.

Is my dog at risk of catching Brucella from other dogs in the UK now?

Despite rising cases, the risk that your dog will catch brucellosis in the UK is still very low, especially if they don’t spend time with untested imported dogs. However, there have been reported cases of transmission between dogs living together in the UK. If you already have a dog and are considering importing another from abroad, make sure they are confirmed negative for brucellosis before they enter the UK.

Published: December 2022


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