Introduction

• Cause: systemic bacterial infection caused by a Gram-negative, intracellular, aerobic coccobacillus bacteria, Brucella canis. Brucella abortus, Brucella melitensis and Brucella suis have occasionally caused canine infections, but comparatively rare.
• Signs:
  • Female - abortion, infertility.
  • Male - epididymitis, orchitis, prostatitis, testicular atrophy, infertility.
  • Non-specific signs: back pain (due to diskospondylitis, lymph node enlargement). 
  • Infection can be asymptomatic. 
• Treatment:
  • Not recommended by Public Health agencies in the UK. Some countries, eg USA, Italy may consider antibiotics as a first line treatment. Antibiotics historically unrewarding at eliminating infection. May reduce antibody titers, without clearing the infection. Failure and relapses occur. No clear way of determining if treatment successful. 
  • Euthanasia: the only way to eliminate the risk of disease transmission. May be the only way to alleviate suffering from clinical signs.  

While not considered to be endemic in dogs in the UK, since summer 2020 there has been a marked increase in the number of dogs identified as being infected with B. canis, mostly in dogs directly imported into the UK from Eastern Europe. This may reflect the higher number of commercial imports from these countries compared to other parts of Europe / internationally. Further information on the risk of Brucella canis infection in imported dogs from endemic countries can be found at: www.bva.co.uk/news-and-blog/blog-article/brucella-canis-what-vets-need-to-know/;
assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/960013/20210210_Brucella_canis_statement.pdf; APHA Canine Brucellosis: Summary Information Sheet.Print off the owner factsheet on Brucellosis infection in dogs to give to your client.
 

Pathogenesis

Etiology

• Causal organism: Brucella canis Brucella canis - gram-negative coccobacillus.
• Brucella abortus, Brucella melitensis and Brucella suis have occasionally caused canine infections.
• The UK is Officially Brucella Free (OBF) of Brucella abortus, Brucella melitensis and Brucella suis. 

Pathophysiology

• Bacteria → mucous membranes (mostly digestive / respiratory mucosa) → lymphatic/genital tract tissue. May also spread to non-reproductive tissues, eg intervertebral disks, eyes, kidneys.
• Highest number of organisms is found in aborted material, urine and semen.

Ingestion or oral contact with

• Aborted fetal or placental tissue.
• Vaginal discharge/female genitalia.
• Mammary secretions.
• Urine.

Mucosal transmission

• Can be transmitted without copulation.

Venereal transmission

• Most common route of infection.
• Semen.
• Prostatic fluid.
• Chronically infected dogs may be serologically negative but organisms persist in urine, prostate, epididymis, within macrophages, leukocytes 'carrier state'.

Timecourse

• Organisms shed for 4-6 weeks following abortion in female.
• Brucella canis may be recovered from an infected male for 7-60 weeks.
• Prolonged bacteremia of 1-2 years not uncommon in non-genital form of disease.
• Pups may be bacteremic for at least 2 months after birth.
• Those that survive may be a source of human infection and in maintaining the bacteria in the canine population.

Epidemiology

• Transmitted via mucous membranes: ingestion/oral, venereal, congenital.

Diagnosis

Treatment

Prevention

Outcomes