Gait analysis in swine, sheep, and goats after neurologic injury: a literature review

Medical research on neurologic ailments requires representative animal models to validate treatments before they are translated to human clinical trials. Rodents are the predominant animal model used in neurological research despite limited anatomic and physiologic similarities to humans. As a result, functional testing designed to assess locomotor recovery after neurologic impairment is well established in rodent models. Comparatively, larger, more clinically relevant models have not been as well studied. To achieve similar locomotor testing standardization in larger animals, the models must be accessible to a wide array of researchers. Non-human primates are the most relevant animal model for translational research, however ethical and financial barriers limit their accessibility. This review focuses on swine, sheep, and goats as large animal alternatives for transitional studies between rodents and non-human primates. The objective of this review is to compare motor testing and data collection methods used in swine, sheep, and goats to encourage testing standardization in these larger animal models. The PubMed database was analyzed by searching combinations of swine, sheep, and goats, neurologic injuries, and functional assessments. Findings were categorized by animal model, data collection method, and assessment design. Swine and sheep were used in the majority of the studies, while only two studies were found using goats. The functional assessments included open pen analysis, treadmill walking, and guided free walking. Data collection methods included subjective behavioral rating scales and objective tools such as pressure-sensitive mats and image-based analysis software. Overall, swine and sheep were well-suited for a variety of assessment designs, with treadmill walking and guided free walking offering the most consistency across multiple trials. Data collection methods varied, but image-based gait analysis software provided the most robust analysis. Future studies should be conducted to standardize functional testing methods after neurologic impairment in large animals.