A nine month old, spayed female, domestic cat became neurologic and was unresponsive to supportive treatment. Upon death, the head and three sections of liver were submitted to the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) for histopathologic evaluation and toxicology testing. Following a negative rabies test, a portion of fixed brain was examined and the white matter of the cerebrum, cerebellum and brainstem were found to exhibit moderate diffuse spongiosis. White matter spongiosis with no inflammatory response is the central nervous system lesion associated with bromethalin intoxication. No significant microscopic lesions were observed in the fixed liver. A portion of fresh brain was extracted and desmethylbromethalin (DMB) was confirmed by liquid chromatography – tandem mass spectrometry (LC-MS/MS).
Bromethalin is a neurotoxic, non-anticoagulant rodenticide that damages the central nervous system by uncoupling mitochondrial oxidative phosphorylation. It is quickly metabolized to DMB, the toxic metabolite. Clinical signs of intoxication can include lethargy, hind limb weakness, muscle tremors, hyperthermia, hyperexcitability, focal or generalized seizures, and paralysis. Onset of clinical signs can occur within 24 hours of ingestion.
Diagnosis of bromethalin intoxication is only available in post-mortem samples. A minimum of 1 gram of brain, adipose and/or liver is required for analytical testing.
For more information about TVMDL’s test offerings, visit tvmdl.tamu.edu or call 1.888.646.5623.
REFERENCES
Method for the Detection of Desmethylbromethalin in Animal Tissue Samples for the Determination of Bromethalin Exposure in Journal of Agricultural and Food Chemistry. 2015, 63, 5146 – 5151