Utilizing historical study data to reduce numbers of extra rodents ordered for nonclinical toxicology studies

SOT 2023 -- The use of rodents as a small animal in vivo model for nonclinical drug safety testing is essential as part of IND and NDA applications to the FDA. More animals are often required for small animal studies compared to large animal studies due to various factors, including blood volume limitations and sample size needed for significant analysis. Animals are assigned to various subgroups based on the amount and type of sample needed, and spare animals are ordered to be available to replace animals that don't meet criteria to be placed on study. Exclusion criteria for animals on study varies based on the study design, and can include clinical signs noted on arrival, body weight, the presence of ophthalmology findings and interactions with cagemates. Exclusion criteria also can vary between subgroups on study based on the type of samples being collected. The recommended number of spare animals to order ranges from 5-10% based on species and study design. We performed an analysis of small animal (mouse and rat) ordering practices for general nonclinical toxicology studies at our test facility in Somerset, NJ to identify the average number of spares ordered and the average number used per study.