In the last few years, cases of canine Brucellosis in the UK have been on the rise. Whilst this remains an uncommon disease in the UK; there is a need for The VPG to address our approach to the handling of samples in patients at increased risk of infection, as this is a zoonosis and poses a potential risk to our laboratory staff. The vast majority of infection is seen in dogs that have originated abroad. Currently there is no specific guidance for testing of dogs from Ireland but in order to minimise risks to our colleagues in our Irish lab, we would ask that relevant travel history is indicated at the time of sample submission.

What is Brucella canis:

Brucella canis, the primary cause of canine brucellosis, is an intracellular Gram negative bacterium. Dogs and other wild canids are the natural reservoir host, but it poses a zoonotic risk to owners, veterinary staff and laboratory personnel. Canine Brucellosis can lead to a variety of symptoms including reproductive tract signs (orchitis, epididymitis, abortion, vulval/preputial discharge, testicular atrophy, infertility) but also discospondylitis, uveitis, polyarthritis, and eningoencephalitis. However, most infected dogs are subclinical yet can remain a vehicle of disease transmission.

The predominant route of dog-to-dog transmission is through coitus and by vertical transmission from dam to offspring. However, the organism is shed in all body secretions and infection can arise from direct contact between mucocutaneous sites and the secretions, excretions and tissues of infected dogs (including urine and milk).

Submission of samples to VPG from dogs with a travel history

If the patient has a travel history outside the UK or was initially imported from a foreign country, please tick the relevant box on the submission form. If known, give details of the countries involved and import dates where possible. This highlights the potential risk to our laboratory personnel and extra precautions can be adopted when handling these samples.

Ideally, travelled dogs will have been previously screened for Brucellosis using the APHA serology tests. Test results can then be included on the VPG submission form allowing samples to be handled as normal. We ask where possible to state the test method used.

• Biochemistry/Haematology/ Endocrinology/Serology: We are able to perform routine biochemistry, haematology, endocrinology, serology etc on samples from travelled dogs. Please still mark the submission form as a travelled dog as extra precautions and additional PPE are adopted when handling these samples.

• Cytology/Histopathology: We are able to perform cytology and histology on samples from travelled dogs. Most histopathology samples with a zoonotic risk (such as Brucella) will be fixed for a further 24 hours upon receipt at the laboratory. Please still mark the submission form as a travelled dog as extra precautions and additional PPE are adopted when handling these samples.

•  Microbiology: For health and safety reasons, bacterial culture may not be possible on certain samples as potential multiplication of Brucella organisms during the culture process poses the biggest risk to laboratory personnel.

Our aim is to limit disruption to the service we offer our clients on samples with minimum risk, whilst maximising safety for our staff when handling high risk samples.

Routine urinalysis, faecal analysis, and skin scrapes can be performed using extra precautions but bacterial culture will depend on the site:

Very high risk samples: Reproductive swabs/fluids (e.g. prostatic wash, vulval/preputial discharge, aborted material) from patients with a travel history will NOT be cultured at the VPG unless the patient has a combined negative Brucella canis SAT and iELISA test (VPG code: BRUCSI) from the APHA (takes 7-10 days). If a culture is required, we can forward the sample to the APHA for culture but this can take a variable amount of time to obtain a result.

High risk samples: Other sites which can be associated with clinical disease (e.g. CSF, synovial fluid, intervertebral disc material, blood). Samples from these sites in patients with a travel history will only be cultured by the VPG when the patient has either a negative Brucella SAT and/or iELISA from the APHA (takes 7-10 days), or a negative FASTest (same day turnaround), which we can run at the VPG provided a serum sample is submitted. (VPG codes: see below).

Medium risk: Sites where bacteria may be found (e.g. Urine, milk). These will be cultured by the VPG if the patient has either a negative Brucella SAT and/or iELISA from the APHA (takes 7-10 days), or a negative FASTest (same day turnaround) which we can run at the VPG provided a serum sample is submitted, or the patient can be downgraded to a low risk category on the basis of history (e.g. a pet dog bred in the UK which is neutered and only travels on holiday with an owner where it is walked on a lead versus an imported dog with unknown history that was only castrated on arrival into the UK). (VPG codes: see below).

Low risk (but not no risk): Sites where the bacteria is unlikely to be found (e.g. faeces, body cavity fluids, BAL, skin/ear/eye swabs, wounds etc). These samples will be cultured by the VPG using precautions.

Serology testing of imported dogs:

The most recent (February 2023) recommendation from the APHA for serology testing of imported dogs is to run a combination of 2 serology tests to increase the sensitivity of detecting disease.

They recommend both the Brucella canis SAT (serum agglutination test) and Brucella canis iELISA (indirect enzyme-linked immunosorbent assay) (VPG code : BRUCSI)

If either test is positive, the sample is considered serologically positive. If both tests are negative, then the sample is considered serologically negative. Using this approach gives an estimated sensitivity of 90% and specificity of 99%.

The 2 tests work well in tandem as the SAT is more sensitive to IgM antibodies which are abundant during early stages of infection whilst the ELISA detects IgG antibodies which are more abundant after the early stages of infection and during chronic infection.

Antibodies are typically produced within 2 weeks of infection but, some dogs take up to 3 months to seroconvert. If screening serology is negative (particularly if clinical signs are suspicious of Brucellosis) and the dog has only recently been imported, then serology should be repeated 3 months from when the dog last had potential exposure to disease.

Samples can either be sent directly to the APHA or submitted to the VPG as usual and we will forward them on to the APHA for testing.

Turnaround time: 7 to 10 days. Sample requirement: 2ml serum.

Which dogs to test:

In 2020/21 there was an increase in cases of Brucellosis in UK dogs most of which had been imported from Romania and Eastern Europe or had close contact with dogs that had travelled to these areas. Routine testing was initially only advised for this group. However the increasing numbers of dogs being imported into the UK (Western Europe generally), free movement of dogs within Europe (often with a lack of movement history), and the occurrence of the disease in large parts of the world (including Middle East, Africa, North and South America, Asia, Mediterranean, Central and Eastern Europe) has meant that most travelled dogs could potentially have been exposed to disease. Patients may present with clinical signs but are often subclinical.

Until more epidemiological data is available to guide recommendations, we advise testing any dog with a travel history outside the UK (with the exception of Australia and NZ which have rigorous testing and quarantine requirements).

VPG test codes:

Brucella canis SAT (VPG code : BRUCAS)

Brucella canis ELISA (VPG code : BRUCEA)

Brucella canis SAT plus Brucella canis ELISA (VPG code : BRUCSI) Recommended

Other tests:

• Brucella canis FASTest (VPG code : BRUF – please call to discuss with our pathology team) – this is a qualitative lateral flow test yielding either a positive or negative result. We are currently using this test to screen for potential disease in travelled dogs where Brucellosis is not suspected clinically but APHA serology has not yet been performed. A negative result will allow us to progress with bacterial culture of certain submitted samples (see high and medium risk samples above).

The test is being performed to reduce the risk to laboratory staff and allow requested tests to be performed in a timely manner. It should not be relied upon as the sole test to determine a dogs serology status and should be followed up with the APHA serology tests mentioned above. There is limited data available to evaluate this test as yet. In dogs with clinical disease it appears reasonably sensitive but can be prone to analytical error.

• Brucella canis RSA (Rapid slide agglutination test) – this is a qualitative test yielding only a positive or negative result. It is run by the APHA and largely superseded by the iELISA.

What to do in the event of a positve result:

Please find a link to the APHA Canine Brucellosis summary sheet. This contains useful information about the disease and the recommended actions in the event of a suspect Brucella canis case or a positive Brucella canis result.

Canine-Brucellosis-Summary.pdf (defra.gov.uk)

We are available to discuss how this may impact your practice, so that you can manage your treatment plans and client expectations. Please contact your local VPG laboratory.

***These recommendations may change as further epidemiological data becomes available ***