What to do when the pub has no beer. Or milk.

Sometimes mother’s milk is not available.  The mare cannot provide for the foal and there is no readily obtainable source.  Perhaps a nurse mare is not accessible or not affordable.

As replacers are more concentrated than mare milk, correct dilution with water is essential.  Dry matter percentage at final dilution should attempt to match that of mare’s milk at approximately 10-15%.¹  This may differ from the targeted concentration of the milk replacer.  Make sure you calculate well.  Increased osmolality (concentration) of milk replacer as compared to mare milk may lead to constipation, hypernatremia (elevated sodium concentrations in the blood), and dehydration in the compromised foal.  Additionally, the higher osmolality of the milk replacer may induce an osmotic diarrhea (concentrated ingesta draws water into the gut).  Bovine-based milk replacers contain sugars not normally found in mare’s milk or in different quantities.  This may promote diarrhea as foals may not have the correct gut enzymes to digest these sugars.²

Usage of milk replacer can be avoided with some planning.  Mare’s milk freezes well.  It is a good idea to collect milk in advance from a healthy donor mare who has a surplus and freeze it.  You are dealing with horses – you can never be too prepared.  Make sure you observe good hygiene during all stages of collection and storage.  Alternatively, other species milk can be used with modifications.  A good source of information on this is contained here.³

Offering donor milk or replacer to the orphan foal can be challenging.  The least demanding technique is to offer the foal a regular amount in a bucket placed in an accessible location.  This is usually accepted rapidly, although training for a few days may be needed.  Up to 25% of bodyweight of milk replacer diluted to 10% divided into 3-5 feedings daily was reported to allow appropriate growth rates with minimal occurrence of diarrhea.⁴  Bottle feeding is also possible, however this is considerably more labor intensive and a period of training of the foal is still required.  Complications include insufficient intake and aspiration pneumonia resulting from foal swallowing problems or poor operator technique.  If the foal is compromised or unwilling to drink, an indwelling nasogastric tube can be placed for use with bolus feedings.  However, hourly feeding may be required as the volume required in each meal to feed an adequate daily amount may exceed the capacity of the stomach.

Although enteral nutrition is preferable, there are situations where a foal may be unable to utilize enteral nutrients or tolerate the required volume to support basal metabolism and growth.  In these cases, intravenous (parenteral nutrition) may be used.  However, nutritional requirements cannot be completely met by this route and diminished gastrointestinal function may result from chronic duration.  Close monitoring of administration is also required to avoid deleterious effects as it is challenging to achieve higher rates of energy administration without causing hyperglycemia in the sedentary compromised neonate.  Provision of calories for short term nutritional support (up to 24 hours) is most simply achieved by solutions of dextrose alone however this is an incomplete nutritional source.  Caloric content of a 5% dextrose solution is 0.17 kcal/mL, so to provide approximately 40 kcal/kg/d an infusion of 10 mL/kg/h must be used.  For an average foal (50kg bodyweight) this totals 12L per day and this volume will likely not be well tolerated by the foal.  Higher concentrations of dextrose are therefore needed: a 50% solution of dextrose provides 1.7 kcal/mL at an infusion rate of 1 mL/kg/h providing approximately 40 kcal/kg/d.  This must be administered with a pump and concurrent isotonic fluids to avoid severe vascular injury predisposing to thrombosis.  Alternatively, a 10% dextrose solution made in isotonic fluids can be administered, not as a bolus but continuously such as a pump will allow.  After this period, the addition of enteral feeding or transition to a more complete parenteral formulation is required (provision of amino acids and possibly lipids).  The addition of amino acids is easily accomplished using proprietary mixes.  Provision of energy and avoidance of protein catabolism is more easily achieved.

Foals can’t always feed as nature would have them.  In those cases, we need to bypass the gut until they can take care of themselves.  This is complicated territory and hospitalization under veterinary care will likely be needed.

1. Glendinning SA. A system of rearing foals on an automatic calf feeding machine. Equine Veterinary Journal 1974;6(1):12-16.

2. Roberts MC. The development and distribution of mucosal enzymes in the small intestine of the fetus and young foal. Journal of reproduction and fertility Supplement 1975;(23):717-723.

3. Stoneham SJ, Morresey P, and Ousey J. Nutritional management and practical feeding of the orphan foal. Equine Vet Educ 2016;29(3):165-173.

4. King SS and Nequin LG. An artificial rearing method to produce optimum growth in orphaned foals. Journal of Equine Veterinary Science 1989;9(6):319-322.