71 - Canine Brucellosis

Abstract

•First Described: Brucella canis was first isolated from dogs by Leland Carmichael in 1966 (United States).•Causes: Most commonly Brucella canis; rarely Brucella abortus, Brucella suis, or Brucella melitensis. Brucella organisms are small (1.0 to 1.5 μm), gram-negative, non–spore-forming aerobic coccobacilli.•Affected Hosts: The Brucella genus is composed of 12 classical species based on host preference, phenotypic characteristics, and genetic analysis: B. abortus (cattle), B. canis (dogs), B. melitensis (goats, sheep), Brucella neotomae (rodents), Brucella ovis (sheep), Brucella pinnipedialis (seals), Brucella ceti (porpoises, dolphins, whale), Brucella microti (voles), Brucella inopinata (unknown host), Brucella papionis (baboons), Brucella vulpis (foxes), and B. suis and its biovars (pigs, cattle, hares, rodents, and wild ungulates). Although most Brucella, with the exception of the biovars of B. suis, show host preference, they can also infect other host species. Brucella canis has a limited host range; only dogs and wild Canidae have been found to be susceptible. Rural dogs are susceptible to clinical infection with B. abortus, B. suis, and B. melitensis.•Geographic Distribution: Worldwide, but infections are most often reported from the southwestern United States, Central and South America, China, and Japan. Sporadic reports have occurred in Canada and throughout Europe. Australia and New Zealand appear to be free of the disease.•Route of Transmission: Direct mucosal exposure (oral, nasal, conjunctival, venereal) to contaminated body fluids (semen, vaginal discharge, urine, aborted fetuses, and their placentas).•Major Clinical Signs: Most commonly infertility, abortion, scrotal enlargement secondary to epididymitis/orchitis, scrotal dermatitis, eventual testicular atrophy, lymphadenomegaly, splenomegaly, signs related to discospondylitis (spinal pain, pelvic limb paresis, or paralysis), uveitis, chorioretinitis, rarely osteomyelitis and meningoencephalitis. No signs may be present.•Differential Diagnoses: Herpesvirus infection, bartonellosis, mycobacterial infections, chronic vector-borne diseases associated with splenomegaly such as ehrlichiosis and babesiosis, coxiellosis, other bacterial and fungal causes of metritis, orchitis/epididymitis, and discospondylitis, intervertebral disc disease, hemic neoplasia (such as lymphoma or multiple myeloma). Additional differential diagnoses for dogs with ophthalmitis include deep mycoses, rickettsial diseases, leptospirosis, and toxoplasmosis.•Human Health Significance: Brucella canis can be transmitted to humans and most often causes mild, influenza-like illness.