Brucella suis is a zoonotic disease of feral pigs that also affects pig hunting dogs, pig hunters, veterinarians and veterinary staff. In recent years the incidence of B. suis in the eastern Australian states of New South Wales (NSW) and Queensland (QLD) has increased. A cross-sectional study was conducted to document the seroprevalence, geographical extent and risk factors for B. suis in dogs at-risk of contracting the disease. Eligible dogs were those that were known to hunt or consume feral pig meat. Dogs were enrolled through private veterinary clinics and/or directly by District Veterinarians in six regions of NSW and QLD. Blood was collected by venepuncture and tested for B. suis antibodies using the Rose Bengal Test (RBT) followed by a Complement Fixation Test (CFT) if they returned a positive RBT. Owners were invited to complete a questionnaire on the dogs' signalment, husbandry including hunting practices and locations, and any clinical signs referable to brucellosis. Of the 317 dogs included in the prevalence survey, 21 were seropositive returning a survey-adjusted true seroprevalence of 9.3 (95% CI 0.45 to 18) B. suis positive dogs per 100 dogs at-risk. True seroprevalence ranged from 0 to 24 B. suis positive dogs per 100 across eastern Australia, with the highest prevalence in central west NSW and southern QLD. Adjusted for other factors, dogs that shared a household with other seropositive dogs and those that traveled away from their home regions to hunt were more likely to be seropositive. Clinical signs at presentation were not predictive of serostatus, with seropositive and seronegative dogs equally likely to present with signs consistent with brucellosis. The results obtained from this study show that B. suis exposure is relatively common in dogs that have contact with feral pigs, with one in 10 testing seropositive. Further studies are needed to understand the progression and risk of transmission from seropositive dogs.

Brucella suis is an emerging, zoonotic disease predominantly affecting dogs and humans that engage in feral pig hunting in Australia and other countries. Although B. suis infection in dogs shares some clinical similarities to the host-adapted species (B. canis), B. suis remains an incompletely understood pathogen in dogs with limited published data on its pathogenesis and clinical features. This case series describes the presentations, diagnosis, and clinical management of B. suis infection in three dogs: (1) a bitch with dystocia, abortion and mastitis; (2) an entire male dog with septic arthritis and presumptive osteomyelitis; and (3) a castrated male dog with lymphadenitis. Unique features of these cases are reported including the first documented detection of B. suis from milk and isolation from lymph nodes of canine patients, as well as the follow-up of pups born to a B. suis-infected bitch. Consistent with previous reports, all three dogs showed a favourable clinical response to combination antibiotic therapy with rifampicin and doxycycline. Individually tailored drug regimens were required based on the clinical presentation and other factors, including owner expectations and compliance with therapy as well as a zoonotic risk assessment (generally considered low, except around time of whelping). The authors include their recommendations for the clinical management of dogs that are at-risk or seropositive for B. suis with or without clinical signs or laboratory-confirmed infection.

Background: Brucellosis in dogs caused by Brucella suis is an emerging zoonotic disease. Objectives: To document clinical characteristics, serology, microbiology, and clinical response to treatment in B. suis-seropositive dogs. Animals: Longitudinal study of 27 privately-owned dogs. Dogs that tested positive by serology, culture, or real-time polymerase chain reaction (qPCR) were included in the study. Methods: Clinical (physical examination and imaging) and laboratory (serology, hematology, serum biochemistry, and qPCR or culture) assessments were made at baseline and after approximately 3, 6, 12, and 18 months. Results: Dogs were followed for 10 895 dog days, with 17/27 dogs completing the 18-month follow-up. Ten dogs had signs consistent with brucellosis before enrollment (n = 4), at baseline (n = 2) or during follow-up (n = 6), with 2 dogs experiencing relapse of historical signs. Antibody titers persisted for the duration of follow-up in 15/17 dogs (88%). Radiographic (n = 5) and ultrasound (n = 11) findings, of variable clinical relevance, were observed. Brucella DNA and organisms were detected in 3 dogs, all of which had clinical signs, including in the milk of a bitch around the time of whelping. Brucella DNA was not detected in blood (n = 92 samples), urine (n = 80), saliva (n = 95) or preputial swabs (n = 78) at any time during follow-up. Six dogs underwent treatment, all of which achieved clinical remission although remission was not reflected by decreasing antibody titers. Conclusions and Clinical Importance: Most dogs with B. suis infections have subclinical infections. Serology is poorly associated with clinical disease. Excretion of