AHL LabNote 61-Brucella Canis Resources and Information for Veterinarians

With the current interest in this testing at AHL please see below a brief review of testing and some resources for more in depth information.

Test offered at AHL is the RSAT Brucella canis test. (code bcarsat)

0.5 mL serum.

Collect in red-top vacutainer tube or equivalent.

Ship in insulated container with freezer packs. TAT 1-7 days.

The D-TEC® CB Canine Brucellosis Antibody Test Kit is a Rapid Slide Agglutination Test (RSAT)

RSAT:

  • Screening test with a high sensitivity but the potential for false positives.
  • High sensitivity in animals infected >1 month prior to testing.
  • May become positive 1-4 weeks after exposure          

2ME-RSAT:

  • More specific test used on samples that are RSAT positive
  • Positive results are strongly supportive of infection

Please note the RSAT testing offered at AHL is a two step process. If the RSAT is reactive then the 2ME-RSAT is done as part of the same testing procedure and cost.

Further confirmation can be done by AGID, PCR or culture. This is most valuable to confirm positive results.

AGID (send out)

  • Another confirmatory test that can be used on RSAT positive samples.
  • High specificity. As with 2ME-RSAT, positive results are strongly supportive of brucellosis

PCR (send out)

  • Can be performed from blood (EDTA), vaginal swabs, preputial swabs or urine
  • Positive results are confirmatory. Negative results do not rule out brucellosis so it should not be used as a screening test.

Culture

  • Can be performed from blood (specific blood culture vials are required – whole blood or EDTA blood will be rejected) , vaginal swabs, preputial swabs or urine
  • Blood cultures are best performed in a series of three, collected at least 24 hours apart preferably while the animal is febrile, to determine if the animal is bacteremic.
  • Positive results are confirmatory. Negative results do not rule out brucellosis so it should not be used as a screening test.
  • Sample handling is critical to reduce false negatives. Please contact AHL ahlinfo@uoguelph.ca or 519-824-4120 et 54530 for further information before sending samples.

Please note – both PCR and culture on blood may only be positive during the initial acute febrile stage of the disease.

Because the organism can be sequestered in the body, dogs can exhibit a range of serological reactions over time, potentially alternating positive and negative results. In cases of chronic infection, serology is not a useful tool to monitor response to therapy.

Resources:

Dr Scott Weese - Worms and Germs Blog

https://www.wormsandgermsblog.com/2019/03/articles/animals/dogs/brucella-canis-in-imported-dogs-ontario/

https://www.wormsandgermsblog.com/2019/03/articles/animals/dogs/brucella-canis-ontario/

CDC Emerging and Infectious Disease article

https://wwwnc.cdc.gov/eid/article/24/8/17-1171_article

Brucella canis factsheet (Center for Food Security and Public Health)

Best Practices for Brucella canis Prevention and Control in Dog 

Jim Fairles

Client Services Veterinarian

Animal Health Lab, University of Guelph ahlinfo@uoguelph.ca 519-824-4120 ext 54530