Feeding the Aged Horse and the Orphan Foal

Every horse ages as an individual. There is no specific age at which a horse becomes a senior; however, most show physical signs of aging by 20 years old (1). The decision of whether to alter an aged horse's diet should depend on body condition, health status, and exercise level, not simply on age. The notion that aged horses lose weight simply because they are older is outdated and disproved. Age alone does not cause a decrease in digestive efficiency (2).

It is abnormal for an otherwise well-managed horse of any age to experience sudden or unexplained weight loss, and therefore understanding the cause of weight loss is critical. However, aged horses often lose weight because of dental wear, metabolic disorders, or simple dietary mismanagement. In the author's experience, dietary adjustment to accommodate poor dentition (ie, providing soaked feeds and soaked forage substitutes, such as soaked hay cubes and/or beet pulp) is very helpful for maintaining condition. Feeding a complete pelleted ration (alone or in combination with forage substitutes) designed for aged horses or easily chewed hay cubes or soaked pellets could improve the horse’s well-being if its teeth are a problem.

Equine animals with metabolic disease need carefully balanced diets to decrease the risk of hyperinsulinemia while also maintaining a proper plane of nutrition and energy intake (see under equine metabolic syndrome in Nutrition for Specific Diseases or Disorders). Similarly, aged horses that tend to gain weight or maintain condition easily also need a balanced, forage-based diet to thrive. However, a thorough medical and dental workup, along with a nutritional evaluation, should be performed before drastically changing an aging horse's ration. Any dietary changes should always be made slowly, over a minimum of 2 weeks, to minimize the risk of digestive upset.

Nutritional management of the orphan foal will depend on the foal's age when the dam is lost. If an orphan foal has not received colostrum from its dam, it must receive either colostrum from another mare or frozen-stored colostrum within 24 hours of birth—preferably within the first 3–12 hours. Antibody-rich plasma-replacement products for IV administration are available but are expensive and provide protection of questionable duration.

A nurse mare is best for the overall care of an orphan foal. The mare and foal should not be left unattended until the mare has accepted the orphan; physical or chemical restraint of the mare might be required initially and repeated on several occasions before she will accept the new foal. If she is in a late stage of lactation (> 3 months) and the foal is a neonate, supplementation with a foal milk replacer could be necessary, because the nutrient content of the milk naturally declines over time.

Milk from cows and goats has been used for orphan foals but could pose a risk for digestive problems such as diarrhea or constipation/colic. Cow's milk is higher in fat and lower in sugar than mare's milk and can be modified by using 2% milk and 20 g dextrose/L (sucrose should be avoided). Goat's milk is also higher in fat and energy and might be more easily digested; however, it carries a higher risk for constipation and/or metabolic acidosis (3).

Commercially manufactured mare’s milk replacers have also been used successfully to feed orphan foals. Foals under 2 days old should be fed hourly, then every 2 hours for the next 2 weeks. Subsequently, a gradual decrease in frequency and increase in volume can occur, so that by 8 weeks, the foal is receiving four feedings daily. Volume per feeding can vary, because commercial milk replacers may have higher energy density than natural mare's milk; however, feeding a slightly diluted commercial milk replacer at higher volumes can help acclimate the foal to the milk replacer and satisfy its appetite with increased volume. Mare's milk averages approximately 2.13 MJ/L (500 kcal/L), so milk replacers can be mixed accordingly (4).

Manufacturers of milk replacer should provide calorie information on the label or over the phone. Feeding volume may range from 250 to 500 mL per feeding, using a warmed milk container and an artificial nipple. Of the various artificial nipples available, those designed for use by lambs are well-suited for foals. The feeding intervals may be lengthened gradually after 2 weeks; however, the amount per feeding also should be increased so that the foal consumes 10–15% of its body weight/day in properly diluted milk replacer.

Foals should be encouraged to drink freshly prepared milk out of a bucket, ad lib, early in life. At 3 months old, foals can be encouraged to eat concentrate mixes (with ≥ 16% crude protein designed for growing foals) and be introduced to good-quality hay in addition to the milk or milk replacer. Prior to 3 months old, foals lack the digestive enzymes necessary to digest grains. While they might be curious and willing to sample feeds and forages, digestibility is minimal at this young age. Foals can be weaned off milk replacer as early as 3–4 months old but only once solid feed consumption is approximately 2–3% body weight (dry matter intake) (5). Fresh water should be available to the foal at all times from birth. (Also see Perinatal Mare and Foal Care and Overview of Management of the Neonate in Large Animals.)