It is very sad to report that thousands of horses per year die as a direct result of malnourishment in the United States alone. These horses may range in age from newborns that are removed from the mare or are with a mare that is too malnourished herself to provide milk, up to horses that are kept on inadequate or non-existent pasture areas. In some cases owners leave the horse in someone else's care and misplace their trust, resulting in the horse paying the price. In less common cases a boarding stable fails to feed the horse's left in its care, resulting in the death of many horses if they are not rescued.
Malnourished horses, besides being thin and failing to thrive, will also be more likely to have compromised immune systems, infections, parasite problems and other associated health problems. Most malnourished horses have worms, respiratory infections and complications, as well as greater likelihood of colic and influenza. Hoof problems, joint and muscle problems as well as skeletal problems are often secondary conditions that must be treated in malnourished horses.
Depending on the degree of malnourishment and the length of time the horse has been underfed or starved will greatly affect the chances for a successful recovery. It is estimated by horse rescues that attempt to rehabilitate these unfortunate animals that about 20% of all chronically malnourished horse with secondary health conditions will die despite the best possible efforts of vets and rescue staff.
The first consideration when working with a malnourished horse is to check for any other possible diseases or conditions that may be contributing to the problem. Always keep a malnourished horse well away and isolated from contact with any other horses until they have been vaccinated and vet checked for any contagious diseases. Provide lots of fresh water, as often these horses have had poor water supplies and this can be causing dehydration and digestive problems. Worming and vaccinations should only be done when a vet has indicated that the horse is fit enough to have these treatments, getting the body rebuilt is the first priority.
Although it may be tempting to start feeding high quality hay and grains, this can be too much of a shock for the metabolic and digestive system and may be exactly opposite of what needs to happen. It is important to feed with the horse's long term recovery in mind. Feed several, six or more, small meals of a good quality hay that is free of any alfalfa or clover per day. After the horse has adjusted and there are no signs of colic or digestive problems in one or two weeks, start adding some senior horse feed which is very digestible and has extra nutrients and vitamins. Moistening the feed with water prior to feeding will help with digestion, and a bit of molasses supplements can also be added. If you are turning the horse out be sure the pasture is not too lush or founder and laminitis may be a further complication for this horse.
Avoid any type of exercise if at all possible. If the malnourishment has been chronic it is likely that the body used most of the muscle mass to keep on going, so at least three to four months of rest and eating will be needed before this horse should be ridden or started on a training program.