Clinical Features That Increase Suspicion of Brucella canis Infection in Dogs With Discospondylitis: A Multicenter Case–Control Study

Abstract

Background: Brucella canis is an important cause of discospondylitis in dogs, and brucellosis can be challenging to diagnose. Early recognition could aid in early implementation of precautions to limit zoonotic transmission. Hypothesis/Objectives: To determine whether specific clinical features exist that differentiate Brucella canis infection from other causes of discospondylitis in dogs. Animals: Fifteen dogs with Brucella canis discospondylitis (cases) and 25 dogs with non-Brucella discospondylitis (controls) evaluated between 2010 and 2021. Methods: Multi-institutional retrospective case–control study. Clinical features in cases were compared to those in temporally matched controls using conditional logistic regression analysis. Neurologic examination findings and radiographic findings were documented by a board-certified neurologist and radiologist who were masked to group identity. Results: No case had a history of being bred or kennel housing. Cases were younger (median, 2.6 years) than controls (median, 5.7 years) (95% confidence interval [CI] 0.66–1.00). There were no differences in sex or breed. Compared to controls, cases had a lower odds of neurologic deficits (odds ratio [OR] = 0.03; 95% CI 0.00–0.85), higher odds of C2-C5 involvement (OR = 13.0; 95% CI 1.6–106.7), and higher odds of multiple disc site involvement (OR = 12.0, 95% CI 1.5–95.8). They had a lower odds of neutrophilia (OR = 0.11, 95% CI 0.01–0.92), a higher median hematocrit (50.6% versus 43.7%; OR = 1.49, 95% CI 1.09–2.03), and a higher median lymphocyte count (1.8 × 1000/μL vs. 1.1 × 1000/μL; OR = 2.39, 95% CI 1.05–5.45). There was no difference in the radiographic appearance of lesions between groups. Conclusions and Clinical Importance: Brucella canis infection should still be considered in cases of discospondylitis regardless of neuter status, sex, and breeding history. Clinical features exist that should increase suspicion for brucellosis.