Behavioral Assessment of Vision in Pigs

>Swine (Sus scrofa) are often the 'gold standard' laboratory animal for ophthalmology research due to the anatomic andphysiologic similarities between the porcine and human eye and retina. Despite the importance of this model, few tools forbehavioral vision assessment in pigs are available. The aim of this study was to identify and validate a feasible and reproducible behavioral test to assess vision in a pig model of photoreceptor degeneration. In addition, a robust behavioral test will reduce stress and enhance enrichment by allowing animals opportunities for environmental exploration and by reducing thenumber of invasive experimental procedures. Two distinct behavioral approaches were tested: the obstacle-course test andtemperament test. In the obstacle-course test, pigs were challenged (after an initial training period) to navigate a 10-object obstacle course; time and the number of collisions with the objects were recorded. In the temperament test, the time needed for pigs to complete 3 different tasks (human-approach, novel-object, and open-door tests) was recorded. The obstacle-course test revealed significant differences in time and number of collisions between swine with vision impairment and controlanimals, and the training period proved to be pivotal to avoid bias due to individual animal characteristics. In contrast, thetemperament test was not altered by vision impairment but was validated to measure stress and behavioral alterations inlaboratory pigs undergoing experimental procedures, thus achieving marked refinement of the study.