84 | Canine brucella infection: what’s the REAL risk to vet nurses?

PodcastInfectious diseaseCanine medicine
Written By Laura Jones

This week, we’re chatting about a rare but often controversial disease - canine brucellosis.

 

WEven if you’re not seeing brucella cases, there’s a good chance you’ll be testing for it. It’s a disease gaining more and more attention in veterinary medicine, particularly with the rise of travelling dogs and international adoption from endemic countries.

And if you see a positive result on your in-house test, it comes with a very long list of clinical, legal, ethical, and personal considerations, which can be really challenging to deal with.

So in this episode, we’re going to cover:

  • What brucellosis is and how it affects our patients

  • Where the current evidence stands on testing and treatment

  • The real risks to human health

  • What you need to do when you suspect or are managing a brucellosis patient

  • And how to advocate for safety while still giving great care

So let’s waste no more time and dive straight into the episode.

First things first - what REALLY is brucellosis?

Brucellosis is an infectious and zoonotic disease primarily caused by Brucella spp. Bacteria - small, gram-negative, intracellular bacteria. There are many species of Brucella; dogs are the preferred host for Brucella canis, though exposure to other Brucella species can also occur, usually via exposure to infected large animals.

Brucellosis primarily affects the reproductive organs, including the testicles, prostate, epididymis, uterus and placenta - though systemic infection is also possible.

So how does brucellosis spread?

Dogs become infected via mating, or contact with infected reproductive secretions, urine, or placenta/abortive material. 

Indirect infection usually occurs through ingestion of or exposure to infected material, aerosolised transmission, or fomites. Conjunctival, oronasal, and broken skin exposure is a common route of entry for bacteria into the susceptible host.

Once the new host picks up the bacteria, the pathogen enters macrophages and other immune system cells, where it spreads to the lymph nodes, liver, and spleen. Here, the bacteria reproduce and begin to enter the bloodstream around 1-4 weeks after initial exposure.

The bacteria generally remain in the bloodstream for 3-4 months (though bacteraemia for up to 18 months is reported in some cases), and infection can wax and wane for years.

Antibodies against Brucella are usually present after around 2-4 weeks, but they can take up to 2-3 months to develop in some cases.

Ok, so that’s what Brucella is and how it’s spread - but what does it do?

One of the biggest challenges with brucellosis is that many infected dogs appear healthy or have very vague, chronic signs that we can easily mistake for more common conditions.

Some dogs will be asymptomatic carriers, whilst others can develop longer-term complications that can be easy to miss if you’re not looking.

Most patients with brucellosis are entire dogs, who present with urogenital signs, including infertility, abortion (usually late-term between 45 and 55 days), stillbirth, vaginal discharge, metritis or placentitis. Males commonly present with orchitis or prostatitis.

Alongside these reproductive signs, nonspecific signs such as lethargy, lymphadenopathy, pyrexia and weight loss/poor coat quality are reported.

In neutered dogs, the signs are often vague and may be mild. These include evidence of blepharospasm, miosis and uveitis; arthritis; and discospondylitis, caused by the immune system reacting to Brucella antigens/antibodies, resulting in inflammation.

Who’s at risk, and why is this increasing?

Brucellosis has been gaining attention in the veterinary news for the past few years, and there remain lots of misconceptions and a lack of evidence surrounding the disease and its risk to veterinary staff.

Let’s start with the risks to our patients.

Historically, brucellosis was mainly confined to breeding kennels, rural regions, and certain parts of the US, Eastern Europe, and South America.

However, with the increasing importation of dogs from countries where Brucella is endemic, coupled with inadequate regulation and testing before importation in some regions, we are witnessing a rise in positive cases in the UK and Western Europe, including among rehomed rescue dogs.

Dogs most at risk include:

  • Dogs from at-risk countries, including Romania, the Balkans, Turkey, Eastern Europe, and some parts of Asia, Africa, North and South America

  • Rescued street dogs or ex-breeding dogs

  • Dogs used in illegal or unregulated breeding

  • Any entire dog from an untested source

Some estimates suggest a 5-8% prevalence in imported dogs from high-risk areas. In the UK, the number of dogs diagnosed with Brucella canis was three before 2020, compared with 143 between 2020 and 2022, and 134 in 2023. Most of these cases have been imported dogs, or patients linked to imported dogs (eg their puppies, or dogs who have had contact with the birthing materials of an infected dog).

That being said, a recent DEFRA report examined dog-to-dog cross-infection risks and noted that they were negligible to very low, provided the dogs were neutered and living in ‘normal’ pet dog settings. Cross-infection risks increased in entire dogs living in close proximity.

It’s important to note that the figures I’m quoting here are based on dogs testing positive, and just like our other infectious diseases, testing isn’t failsafe. We’ll chat more about diagnosing Brucellosis later in the episode.

What about the risk to human health?

Brucella canis is zoonotic, but not as aggressively zoonotic as some of the other Brucella species which affect livestock. That being said, Brucella canis infection has been documented in a small number of people in the UK.

The government’s HAIRS (human-animal infection and risk surveillance group) investigation has shown the risk of infection in the general population is very low, but higher in Immunocompromised people, pregnant women, children, and elderly individuals, as well as those who care for infected or at-risk dogs.

Like dogs, people who become infected with Brucella canis do not always develop obvious signs. Many symptoms take weeks to years to develop, and, when seen, include:

  • Pyrexia

  • Inappetence and weight loss

  • Headaches

  • Fatigue

  • Muscle and joint pain

  • Recurrent or chronic infection

We lack sufficient evidence to fully understand the human health risks posed by Brucella canis infection during pregnancy. However, infection with other types of Brucella bacteria has been associated with higher complication rates.

Infection with Brucella canis is rarely fatal in humans, and most people will recover fully with antibiotics - though untreated brucellosis can cause longer-term complications like endocarditis and meningitis, as the immune system reacts to the infection.

So, is there a risk with Brucella? Yes, there is - but it’s probably lower than you think. Identifying at-risk patients, barrier nursing them until they’re tested, and taking precautions to protect yourself are essential.

OK, so that’s what brucellosis is and the risks it poses. How will we identify it?

Diagnosing Brucella canis infection isn’t straightforward, and like our other infectious diseases, testing isn’t always 100% accurate. 

In the clinic, we’ll perform a lateral flow test - an initial screening test to look for serum antibodies against Brucella canis, similar to our ‘SNAP’ tests for things like FIV, parvo, and lepto. These provide rapid results in around 10-15 minutes, but aren’t always trustworthy.

Like our other antibody tests, false negative and false positive results can occur. False positive results should be confirmed with external testing, using more sensitive testing methods, including slide agglutination testing (SAT) and ELISA. Again, I want to point out that no testing method - external or in-house - is 100% accurate. And given that most decisions regarding euthanasia are made based on a positive test result, we need to bear that in mind.

Culture or PCR testing may also be performed for definitive diagnosis, depending on local guidance and the individual case. This is useful in the earlier stages of infection, particularly since PCR is more sensitive and can confirm a false-negative result in a clinically suspicious patient.

Whilst most of our diagnostic tests are performed on serum samples, cultures and PCRs can also be performed on urine, semen, and tissue samples.

And, on the topic of urine, if you’re submitting ANY sample to an external laboratory (even a routine urine analysis in a patient with an unrelated disease) from a travelling patient, we must inform the lab of their travel history, and any brucella results we’ve collected from in-house testing. Most laboratories in the UK, at least, will not process urine from dogs without this information, and some will not culture urine from travelling dogs due to the risk to their staff.

Before we move on to treatment, one last tip from me when it comes to diagnosing these patients: Always wear full PPE when collecting or handling samples from a suspected case. That includes gloves, a gown, and eye protection, especially if dealing with blood, urine, or reproductive fluids. Ideally, limit your patient to a consulting room while their in-house test runs. Once you receive a negative result, you can lift your barrier nursing precautions.

And if you’re faced with a true positive result? Well, treatment is tough.

Brucella canis is difficult to eradicate, persists for long periods in the tissue, and patients are prone to relapse, even after treatment. Because of this, and the zoonotic potential of the disease, treatment is usually discouraged. Some countries will recommend euthanasia for confirmed cases, especially in households with vulnerable people, and this comes with real ethical and moral challenges for us as nurses and technicians.

Where clients want to pursue treatment, the options are limited. They usually include neutering entire dogs and administering a combination of antibiotics (for a minimum 2-3 month course) alongside surveillance monitoring protocols and isolation from other dogs.

Even with treatment, the bacteria can persist, and shedding can continue. Though low, the risk to people does not go away, and all people - clients and veterinary staff - need to take appropriate precautions when handling positive or at-risk patients.

So treatment is limited - but what about nursing? Where do we come into things?

There are a few things we need to consider, including infection control, client support and education. 

These patients require isolation and strict barrier nursing, including gloves, a gown, and eye protection. Handle the patient’s body fluids and environment with particular care, especially urine and any reproductive fluids.

We may also be asked by clients about the zoonotic risk or treatment, especially in clients rescuing dogs from endemic countries. Stay factual and defer specific advice to the vet in charge of the case, but also support the client emotionally. This is a really tough situation and a lot to handle.

Caring for a positive dog in the hospital is a difficult situation, and only you’ll know whether you feel comfortable with it. You may feel conflicted between caring for your patients and protecting yourself and others, but hopefully, you’ll feel comforted by the stats we’ve chatted through in this episode, and the fact that the transmission risk is very low in most patients.

Tips for managing suspected brucellosis cases as a VN

I want to leave you with a few tips when caring for at-risk cases:

First, know who’s at high risk

Speak to clients about travel history, origin (imported or rescue dogs), neutering and testing status, and clinical signs.

Then, barrier nurse them from the start.

Starting in the consult until you’ve got a negative test - taking extra care with urine, any reproductive secretions, waste and soiled bedding

Consider the facts

We know that transmission rates are low, and diagnostic results aren’t always 100% accurate.

Take care of yourself.

If you’re caring for a positive patient or you’re having to support end-of-life decisions, it can be really emotionally tough - so get support for you. Speak to your colleagues, debrief with them, and remember that ethical and moral dilemmas are very real in veterinary medicine - and they affect us as nurses and technicians, too.

So that’s it for this episode, all about canine brucellosis. It’s challenging to diagnose, even more challenging to treat, and ethically difficult. And as nurses and technicians, we need to:

  • Understand the disease

  • Know who’s at risk

  • Barrier nurse appropriately

  • Protect ourselves and others

  • And provide support - for our patients, our teams, and our clients

One last thing from me - I’m very aware that this is a controversial and emotionally-charged topic, and I’ve really tried to cover it in an evidence-based way with the information out there. If you want more details on brucellosis, I’d advise speaking with Louise Buckley, aka the Brucella Canis RVN. She has far more experience with this disease than any other nurse I know, and is all about evidence-based nursing, so you’ll be in good hands with her!

That’s it for this week’s episode - thank you so much for learning with me today! I hope you never find yourself in the situation where you’re nursing a brucella patient, but if you are, I hope this episode has left you feeling more aware of the facts and more confident in caring for them.

Did you enjoy this episode? If so, I’d love to hear what you think. Take a screenshot and tag me on Instagram (@vetinternalmedicinenursing) so I can give you a shout-out and share it with a colleague who’d find it helpful!

Thanks for learning with me this week, and I’ll see you next time!


References and Further Reading

Laura Jones
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