Stocked up or stocking up is a phrase used to describe a horse's legs when they are swollen, usually the lower legs or below the knees. Many people will notice that after a night spent in a stall, a horse's legs may appear slightly, or sometimes dramatically, swollen in the morning. Once the horse is turned out and allowed to move around in its pasture, the swelling may disappear.
Stocking up differs from swelling due to injury, in that the horse is unlikely to be lame, and the swelling will be generalized, instead of localized. Usually, the front or back or all four legs will be swollen, rather than one leg—which could indicate an injury. The swelling is normally below the knees and hocks. It also generally subsides as the horse moves around.
Designed for Motion
Horses are designed to move almost constantly. Their hearts pump blood throughout their bodies, including their extremities. The digital cushion in the hooves and soft tissues, such as the leg muscles and tendons, help to circulate the blood as the horse moves its legs. As the blood circulates, it carries nutrients and oxygen to even smaller blood vessels, the smallest being the capillaries in the leg that are generally too small to be seen with the naked eye.
Through the walls of these minute capillaries, the nutrients and oxygen pass into the surrounding tissue. The unused nutrients and any waste are then drained into the lymphatic system, where ideally, they are filtered through the lymph nodes. The blood filters back into the veins, to be circulated back to the heart where, of course, the process is repeated.
Key to this process, is that the pumping action of the digital cushion and to a lesser extent, the muscles, tendons, ligaments, and joints in the legs aid in the circulating and blood cleansing process. For this to happen efficiently, the horse must be moving. When a horse is confined to a stall, where it cannot move freely, this process may be hampered.
As the blood and waste must be pumped up the legs, back to the heart, some of it can pool if the horse is not moving. This pooling results in the swelling that is called 'stocking up.' It is, in fact, edema, and some horses seem to be more prone to it than others. Stocking up may be more likely in older horses, whose circulatory system isn't as efficient as it once was. Some horses may have undiagnosed heart problems, or may have problems that impair the lymphatic system in their legs.
If your horse is prone to stocking up, the best remedy is to allow it freedom in a paddock or pasture where it can be encouraged to move by placing water, feed, and shelter in different places. The more your horse moves, even at a walk, the better. When the weather is not favorable, keep your horse stabled during only the worst part of the day.
If it's impossible to turn the horse out, cold hosing may be the next best option. This may come with problems of its own; effective cold hosing takes time and leaves your horse's legs damp—which might not be a good idea in some conditions. You may also try hand walking as much as possible, even if it is up and down the alley of the barn. Gentle riding can also help.
Some horses seem to respond to certain feeds, so take a look at any changes in the grains or concentrates your horse is consuming. Occasionally, swelling may be related to allergies.
Bandaging, poultices, and liniments may help in the short term, but may cause problems as well. Improperly applied standing bandages may worsen the problem, and topical remedies may cause skin problems.
Winter Care For Horses. Rutgers Equine Science Center.
The 4-H Horse Project. Oregon State University.
Equine Bandaging: Applying a Lower Hind Limb Bandage. Marion duPont Scott Equine Medical Center at Virginia Tech.