—Ashley, via e-mail

A.Probably the most common type of case and questions involving senior horse behavior concerns the horse that is reluctant to lie down, or is not lying down, to rest. After about two to three weeks without even a brief session of recumbent rest with REM (rapid eye movement) sleep, most horses begin to appear sleep-deprived.

They tend to repeatedly nod down to the floor, wake up upon buckling, and might partially or fully collapse to the floor during standing rest. This can occur in younger horses as well, but more often than not the cases we see are in older animals. This is probably because of musculoskeletal conditions common to older horses that might make it more difficult to lie down and get up again. These horses usually are referred to our program because of observed collapse when standing at rest or on the cross-ties, or due to injuries consistent with collapse.

While there are other reasons horses collapse, the cause is often unknown. In these cases we typically recommend a 24-hour (or longer) continuous video evaluation to obtain clues as to why the horse might be collapsing. The video behavior evaluation is often performed simultaneously with a cardiac monitor/recorder to evaluate potential heart problems as a cause of collapse. Another common cause of collapse is a seizurelike event, which can be evaluated using video as well.

If the horse simply appears sleep-deprived, we try to gain insight into physical or environmental factors that might explain why he is not lying down to sleep. In roughly half the cases we can identify factors we can improve to get the horse sufficient recumbent rest and greatly reduce his signs of sleep deprivation.