Clinical presentation and outcome of bromethalin toxicosis in preweaned kittens: a case series

Objective: To document the clinical signs, diagnosis, and outcomes in preweaned kittens with bromethalin toxicosis, and to determine the duration that desmethylbromethalin (DMB) can be measured in serum after bromethalin exposure in kittens. Animals: 5 litters of neonatal kittens with neurologic disease were evaluated. Two litters presented to a veterinary hospital for evaluation, and 3 litters presented for diagnostic investigation following euthanasia. Clinical Presentation: In this retrospective study, physical and neurologic examinations were completed for 5 kittens, with serial follow-up examinations completed for 3 kittens. Autopsies were done in 10 kittens. Tissue (10 kittens) or serial serum samples (3 kittens) were analyzed with LC-MS-MS for DMB. Results: 12 preweaned kittens were diagnosed with bromethalin toxicosis on the basis of clinical signs, autopsy, and measurement of DMB in tissue (n = 10) or serum (2). Ten kittens were tested for and diagnosed with bromethalin exposure on the basis of marked white matter vacuolization on histopathology. Three kittens in 1 litter were diagnosed with bromethalin exposure antemortem directed by autopsy results of 3 littermates. Two of the 3 kittens developed neurologic signs of bromethalin toxicosis that resolved within 6 weeks; the third kitten remained clinically normal. Serum monitoring detected DMB in the surviving kittens for > 30 days after presentation. Clinical Relevance: Bromethalin toxicosis occurs in preweaned kittens, and neurologic signs are not uniformly predictive of a grave prognosis. The laboratory detection of DMB in serum can be a useful method for confirming exposure up to 46 days after exposure.