A rapid serial reversal learning assessment for age-related cognitive deficits in pet dogs

Assessments for behavioral inhibition in pet dogs that can rapidly detect age-related cognitive deficits (ARCD) using inexpensive and accessible materials may aid in diagnosing canine dementia and may facilitate translational research on Alzheimer's disease in humans. In this study, we designed and deployed a spatial serial reversal learning test in which 80 pet dogs were required to learn which of two identical boxes contained a hidden food treat. Each time the dog chose the correct box in three consecutive trials the procedure was repeated using the other box. All dogs that completed shaping (n = 62) also completed the 30-minute assessment. Middle-aged dogs chose the correct box more often than younger and older dogs. This cognitive decline was detectable with a stand-alone score for perseveration that can be easily measured and interpreted by clinicians and dog owners. Age did not predict how frequently the dog learned the serially-reversing reward contingency but older and younger dogs displayed longer streaks of perseverative errors. Thus, ARCD in dogs may be better characterized by bouts of severe cognitive dysfunction rather than temporally-consistent cognitive deficits. We suggest that future ARCD assessments for pet dogs should include measurements for intra-individual variability.