excerpted from Horse and Stable Management by William Hislop, C.E. Howell, and E.B. Krantz, originally published in July, 1916
The serviceability of the work horse may be increased or decreased according to the care which is bestowed upon him. If he is groomed in a perfunctory fashion his efficiency as an animal motor is lessened. On the other hand, if he is well groomed he is snappier and fresher in appearance and is constantly up on the bit. In short, grooming is essential to the health and vigor of the horse.
Horses running on pasture or being roughed through the winter do not require grooming. They do well without it. It is not the fact that a horse is stabled which makes it necessary to groom him, but it is rendered essential by the heavy feeding and hard work done by him. Every highly fed, hard-working horse requires grooming, whether he be kept inside or outside over night.