canis - Articles
Brucellosis
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.
Presenting signs
Female
- Reproductive failure Infectious infertility in the female:
- Abortion Abortion/stillbirth.
- Apparent failure of conception.
- Early embryonic death.
- Generalized lymphadenopathy Lymphadenopathy.
- Lameness, pain.
- Usually afebrile.
- Lethargy.
Male
- Genital disease:
- Epididymitis Orchitis / epididymitis.
- Orchitis.
- Prostatitis Acute prostatitis.
- Scrotal/testicular swelling +/- moist scrotal dermatitis.
- General:
- Generalized lymphadenopathy.
- Often afebrile.
- Infertility Infertility: male - overview.
- Splenomegaly.
- Lameness, pain.
- Subclinical.
Geographic incidence
- USA increased incidence in southernmost states of the USA, Mexico, Central and South America, The People’s Republic of China, and Japan. Sporadic reports in Canada and throughout Europe. Australia and New Zealand appear to be free of the disease.
Public health considerations
- Sporadic cases of human infection reported most commonly following contact with aborting bitches and from canine genital secretions - relatively mild infections (headaches, fatigue, lymphadenopathy, mild pyrexia). Laboratory workers at significant risk - humans relatively resistant unless immunocompromised. Owners should be advised to consult physician.
- May be reportable disease in certain jurisdictions. Infected dogs and bitches should be removed from breeding programs. Eradication in kennel situations has not been successful without removal (euthanasia) of all current or historically affected dogs. In some situations, euthanasia of affected dogs has been advised.
Cost considerations
- Long course of antibiotics required, often unsuccessful.
- Frequent repeat treatments may be required.
- Numerous screening tests expensive.
- Can be devastating in a breeding colony.
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
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Ahmed-Bentley J, Roman S, Mirzanejad Y et al (2021) Laboratory exposures from an unsuspected case of human infection with Brucella canis. Emerg Infect Dis 27, 2489-2491.
- Santos R L, Souza T D, Mol J P S et al (2021) Canine brucellosis: An update. Front Vet Sci 8, 594291 Frontiers.
- Jacobson R H (1996) Laboratory diagnosis of infectious diseases. Semin Vet Med Surg (Small Anim) 11 (3), 133-197 VetMedResource.
- Mateu-de-Antonio E M, Martin M & Casal J (1994) Comparison of serologic tests used in canine brucellosis diagnosis. J Vet Diag Invest 6 (2), 257-259 PubMed.
Other sources of information
- Boyden P (2024) Brucella Canis: What Vets Need to Know. BVA, UK. Website: www.bva.co.uk.
- Barker E & BSAVA Scientific Committee (2023) Brucella Canis. In: BSAVA Scientific Information Documents. Website: www.bsavalibrary.com.
- UK Health Security Agency (2023) Brucella Canis: Information for the Public and Dog Owners. Website: www.gov.uk.
- Public Health England: Human Animal Infection and Risk Surveillance Group (2021) Risk Review and Statement on the Risk Brucella Canis Presents to the UK Human Population. Website: www.assets.publishing.service.gov.uk (pdf download).
- Animal Plant and Health Agency (2023) Canine Brucellosis: Summary Information Sheet for Veterinary Staff. Website: www.apha.defra.gov.uk (pdf download).
- Davidson A P & Sykes J E (2013) Canine Brucellosis. In: Canine and Feline Infectious diseases. Ed: Sykes J E. Elsevier, USA. pp 512-519.
- Farstad Wenche (2004) Infectious Causes of Pregnancy Loss in Dogs. In: Proc American College of Theriogenology Annual Conference. pp 225-230.
- Greene C E (2000) Bacterial Diseases. In: Textbook of Veterinary Internal Medicine. 5th edn. Eds: Ettinger S J & Feldman E C. W B Saunders, USA. pp 183-186.
- Nelson R W & Couto C G (1992) Genital Infections and Transmissible Venereal Tumors. In: Essentials of Small Animal Internal Medicine. Mosby Year Book, USA.