A Technical Guide to Sampling the Beagle Dog Nervous System for General Toxicity and Neurotoxicity Studies.

Beagle dogs are a key nonrodent species in nonclinical safety evaluation of new biomedical products. The Society of Toxicologic Pathology (STP) has published "best practices" recommendations for nervous system sampling in nonrodents during general toxicity studies (Toxicol Pathol 41[7]: 1028-1048, 2013), but their adaptation to the Beagle dog has not been defined specifically. Here we provide 2 trimming schemes suitable for evaluating the unique neuroanatomic features of the dog brain in nonclinical toxicity studies. The first scheme is intended for general toxicity studies (Tier 1) to screen test articles with unknown or no anticipated neurotoxic potential; this plan using at least 7 coronal hemisections matches the STP "best practices" recommendations. The second trimming scheme for neurotoxicity studies (Tier 2) uses up to 14 coronal levels to investigate test articles where the brain is a suspected or known target organ. Collection of spinal cord, ganglia (somatic and autonomic), and nerves for dogs during nonclinical studies should follow published STP "best practices" recommendations for sampling the central (Toxicol Pathol 41[7]: 1028-1048, 2013) and peripheral (Toxicol Pathol 46[4]: 372-402, 2018) nervous systems. This technical guide also demonstrates the locations and approaches to collecting uncommonly sampled peripheral nervous system sites.