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Brucellosis
Erin E. Runcan, DVM, DACVT and Marco A. Coutinho da Silva, DVM, MS, PhD, DACT

Department of Veterinary Clinical Sciences, Ohio State University, Columbus, OH, USA

Etiology/Pathophysiology Epidemiology

Canine brucellosis is caused by the aerobic, gram‐nega- Canine brucellosis is widespread in domestic and feral
tive, coccobacillus species Brucella. The most clinically dog populations throughout the southern United States,
relevant infection in dogs is caused by Brucella canis, in Central and Southern America, and Asia. It is unclear
although reports exist of infection with B. abortus, how important wild canids or stray dog populations
B. melitensis, and B. suis in individual animals. The bac- are in disease transmission. Sporadic cases have been
terium is highly contagious, and often spreads rapidly in reported in Europe. Recently, the disease has become
breeding kennels. Transmission is also possible via fro- more prevalent in breeding kennels due to their growing
zen semen and artificial insemination as the bacterium is number, ease of buying/selling and trading infected dogs,
resistant to cryopreservation. and increased international semen shipment.
The organism is best known for being venereally
transmitted via vaginal and seminal secretions in sexu-
ally mature animals. Transmission also occurs in utero, Signalment
at parturition, or during abortion through oronasal,
conjunctival, or transdermal contact of aborted fetal tis- There are no current recognized breed or age predisposi-
sues, placental tissues, urine, milk, or vulvar discharge. tions. As venereal transmission is most significant, sexually
Aborted tissues are highly infectious, containing high intact, reproductively mature dogs are most likely to become
numbers of organisms, and abortion often results in per- infected, but the disease has been readily identified in both
sistent vaginal discharge that can last for 4–6 weeks. neutered and intact individuals. There has been a case report
Infection can also occur via artificial insemination with of a child becoming infected as a result of contact with an
infected semen, and via fomites such as contaminated infected 8‐week‐old puppy and thus, the disease is zoonotic,
food and water bowls, equipment, and clothing. The especially in immunocompromised individuals.
bacterium is highly stable and can survive for months in
moist soil in the environment.
Following contact, invading bacteria are able to survive History and Clinical Signs
phagocytosis and are taken up by lymphatic and genital
organs where they rapidly reproduce. Bacteremia occurs The majority of individuals infected with B. canis are
1–4 weeks post infection and can persist for up to six asymptomatic. Fever is uncommon and there are no clin-
months. Bacteria can be intermittently detected in tis- ical signs that are pathognomonic. The classic clinical
sues and secretions for up to 64 months post infection. sign is late‐term abortion in bitches, with abortion
While the bacteria reproduce best in reproductive occurring at 45–55 days gestation. Deceased pups are
tissues, a variety of clinical signs can manifest as a result often autolysed, and surviving pups are often weak,
of hematogenous transmission to the eye, kidneys, and have peripheral lymphadenopathy, and may die months
vertebrae. later as a result of bacteremia. A greenish‐gray vulvar

Clinical Small Animal Internal Medicine Volume II, First Edition. Edited by David S. Bruyette.
© 2020 John Wiley & Sons, Inc. Published 2020 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/bruyette/clinical