Clinical signs, risk factors, and outcomes associated with bromide toxicosis (bromism) in dogs with idiopathic epilepsy.

OBJECTIVE: To evaluate clinical signs, risk factors, and outcomes associated with bromide toxicosis (bromism) in dogs with idiopathic epilepsy treated with potassium or sodium bromide.
DESIGN: Retrospective case-control study. ANIMALS: 83 clinically ill epileptic dogs with (cases; n = 31) and without (controls; 52) bromism. PROCEDURES: Medical records were reviewed for information regarding signalment, epilepsy history, treatment, diet, clinicopathologic test results, concurrent diseases, clinical signs, and outcome. Case and control dogs were matched by the veterinary hospitals from which they were referred and by month of admission. A presumptive diagnosis of bromism was made in case dogs when treatment for primary clinical signs was limited to induction of diuresis or reduction in the dose of bromide administered, and this diagnosis was supported by serum bromide concentrations. Potential risk factors for bromism were identified via univariate and subsequent multivariate logistic regression analyses.
RESULTS: Common clinical signs of bromism included alterations in consciousness, ataxia, and upper and lower motor neuron tetraparesis and paraparesis. The multivariate analysis identified bromide dose at admission to the hospital as the only factor significantly associated with bromism. In all dogs with bromism, treatment via dose reduction or facilitated renal excretion of bromide resulted in rapid clinical improvement, although breakthrough seizures happened during treatment in 8 of 31 (26%) dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Bromism is a clinically heterogeneous, dose-dependent neurotoxicosis that is largely reversible with treatment. Regular serial monitoring of serum bromide concentrations is recommended to optimize anticonvulsant treatment in dogs with idiopathic epilepsy.