the gums under the thumb have been blanched out, the thumb can be
removed. The blanched out area should return to normal color in less
than 1-2 seconds.
Note: If the dog is dehydrated, the membranes will be dry and
the capillary refill time will be prolonged (>2-3 seconds).
A dog in shock will also have an increased capillary refill time. A
video of this procedure is found below.