FEEDING THE STARVED HORSE
(click HERE for feeding instructions)
This article will address the issue of starvation in the horse, the physical impact and clinical manifestations that starvation has on the animal, the prognosis for recovery, the problems associated with re-feeding the starving horse and restoring it to health and, the current recommendations for implementing a successful re-feeding program.
The topic of starvation and re-feeding is relevant from a nutritional standpoint because, as with humans, starvation and the subsequent abrupt, and improper, re-feeding of a horse can result in a dysfunction in the animal’s metabolic system and their electrolyte balance. Additionally, problems including fluid overload and thiamine deficiency may also occur. These dysfunctions can cause the heart, kidney and lungs to fail - resulting in death, usually 3 to 5 days after the first feeding.
It is vital that the ‘rescuer’ understand the complications that may occur upon re-feeding the starving equine and the most appropriate method of re-introducing food to the horse, in order to minimize the risk of adverse events.
RISK FACTORS AND CLINICAL SIGNS OF STARVATION
Why would a caretaker allow an equine to degenerate to the brink of starving to death? According to researchers at the UC Davis Center for Equine Health: The most common reason for severely malnourished horses was ‘owner ignorance followed by economic hardship’ ( Stull, 2003). Additionally, the University of Minnesota states that ‘Most cases of starvation or severe malnutrition originate from owners who acquire more horses than they have interest in caring for or the means to care for’ (U of M).
Starving horses may be receiving inadequate or no feed at all. The animals may also have a problem accessing the feed that is provided – as in the less dominant or younger horses in a herd situation. Starving horses may also suffer from medical conditions, including poor dental care or a heavy parasite load, which interfere with their intake of feed and the metabolism, or absorption, of nutrients. The increased demands of cold weather, pregnancy, lactation, or growth will impact the metabolic rate of the horse as well – possibly contributing to their starvation.
Some of the signs of starvation include a skeletal frame with a BCS below 3.5 on the Henneke Body Condition Scoring (BCS) Scale (click HERE), large abdomen, disproportionately large head compared to the body, constipation, diarrhea, poor or abnormal manure output, foul smelling manure, dull or shaggy hair coat that won’t shed, loss of hair, depression, low hanging head, motionless tail & ears, dull & expressionless eyes, lethargy, nervousness, lack of interaction with herd mates, laying down a lot, unable to rise without assistance, colic, difficulty swallowing, stereotypical behaviors including cribbing and repetitive movements and, jaundiced eyes.
Additionally, nutrition consultant Jackie Vandenbrink states that ‘A starving horse most likely has an overall low trace mineral and vitamin status, low electrolyte levels, poor hydration, an empty gut and a lack of digestive bacteria’ (Vandenbrink, 2007).
According to UC Davis, Horses at risk for re-feeding syndrome would include:
- Any animal with a BCS of less than 3.5/9 and an unknown dietary history.
- Animals which have fasted for greater than 5 – 10 days regardless of body condition score
- Animals which have lost greater than 10% of their body weight over less than a 2 month period.
- Animals with hepatic lipidosis, diabetic ketoacidosis and hyperadrenocoticism are at increased risk.
So what is the prognosis for recovery in a starved horse?
The article ‘Saving Survivors’ by Marcia King states that ‘Generally, thin horses recover completely and easily, regaining their full potential. The truly starved horse is another matter’ (King, 2003). In the article, Dr. Carolyn Stull PhD , states ‘With severe starvation, the body doesn’t discriminate which muscles it’s going to use for energy when it is in a truly starved situation. Some tissues can regenerate, but some tissues can’t. These severely affected horses may have cardiac problems or other long-term consequences.’ (King, 2003)
Furthermore, Dr. Stull states in her article ‘Nutrition for Rehabilitating the Starved Horse’ that ‘when a horse loses more than 50% of its body weight, the prognosis for survival is extremely poor (Stull, 2003). Additionally, according to Jackie Vandenbrink ‘If there are no obvious clinical signs of deficiency most horses will recover well from temporary periods of nutrient deficiency.’ She continues by stating that ‘The most obvious exception to this is the pregnant mare and growing foal. Nutrient deficiencies will cause developmental problems that can cause permanent irreversible damage’ (Vandenbrink, 2007).
In a healthy horse, fat and carbohydrates are the primary source of fuel for normal functioning and energy. Proper nutrition and feeding practices provide the essential nutrients necessary to ensure continued functioning and good health. Under normal circumstances, the feed consumed by the animal replenishes the nutrients which have been used up as the horse lives, works, plays, sleeps etc.
In contrast, when a horse suffers from food deprivation/starvation, the fats and carbohydrates are taken directly from the animal’s body to fuel its existence. In the starving horse, these energy sources are not replenished by the intake of nutrients. Eventually, the carbohydrate and fat energy supplies, located in the body, are depleted - forcing the horse to ‘tap into’ an alternative energy source. The fuel that replaces the fats and carbohydrates is the protein found in the tissues of the body.
However, protein is not stored in reserve - as fats and carbohydrates are. Therefore, the energy the horse needs for normal functioning is derived from the breakdown of protein - which is a component of every tissue in the body. In addition to utilizing the protein found in muscle tissues, a starving horse will take protein from vital tissues as well - including the gastrointestinal tract and the heart.
CAUSES OF REFEEDING SYNDROME
In a manner similar to humans, the feeding of concentrated calories to a starving horse can lead to a condition called ‘Re-feeding Syndrome’. This syndrome can cause kidney, heart and respiratory failure 3 to 5 days after the first feeding.In ‘Saving Survivors,’ Dr. Stull explains that, ‘When you introduce calories you have an elevation in the insulin, when insulin increases; it starts an electrolyte shift that ultimately can cause a respiratory compromise. Consequently, red blood cells collapse; with that, the patient doesn’t have adequate oxygen transfer and the horse goes into this irreversible condition that can lead to death.” (King, 2003)
Electrolyte imbalances are at the root of the complications associated with ‘re-feeding syndrome’. The more notable problems include hypomagnesaemia, hypokalemia and hypophosphatemia. When carbohydrates, or glucose, is fed to the starving animal these electrolytes are driven into the intracellular compartment causing a severe deficiency of serum electrolyte levels (UC Davis, Shelter).
When a starving horse is fed a high carbohydrate meal, insulin is released in response to the high starch levels. Insulin is a hormone that stores carbohydrates in cells for use as an energy source. At the same time, the released insulin pulls magnesium and phosphorous out of circulation and into the cell. During starvation the horse’s electrolytes have been depleted and the starved horse doesn’t have additional stores available for normal functioning. During the course of the next several days a cumulative effect occurs during each feeding of high carbohydrate feed. The continued depletion of these electrolytes can lead to death by respiratory, cardiac or kidney failure. In such cases, death usually occurs within 3 to 5 days.
For a refeeding protocol, click HERE to continue this article.....
Stull, Carolyn, PhD, July 2003, The Horse Report, UC Davis, Volume 21, Number 3, pp456-457 ‘Nutrition for Rehabilitating the Starved Horse’, UC Davis Medical Center.
Witham, Christine L. DVM, MPVM, Stull, Carolyn L. MS, PhD, (1997) Refeeding the Starved Horse: Metabolic Responses to Three Isoenergetic Diets, Authors’ address: Veterinary Medicine Extension,School of Veterinary Medicine, University of California at Davis, Davis, CA 95616.AAEP.
Vandenbrink, Jackie, (March, 2007), Nutrition Guest Speaker. http://sheltermedicine.com/portal/is_starvation.shtml
UC Davis Koret Shelter Medicine Program
University of Minnesota, FAQ About Rescue Horses, College of Veterinary Medicine.
#5378 January 2005, ‘AAEP 2004: How to Manage Starved Horses and Effectively Work with Humane and Law Enforcement Officials
King, Marcia, April 2003, ‘Saving Survivors, Article # 4283
http://www.riovistaproducts.com Helpful Tips for Refeeding a Neglected Horse
By Carolyn Stull, the 2001 Hank Award Winner in the category of PHD/Veterinarian
Basic Guidelines for Operating an Equine Rescue or Retirement Facility
Henneke et al, 1983, Equine Vet Journal, pp 371 – 372, Body Condition Scoring
Dawson, Robert O., Professor of Law, University of Texas School of Law
(March, 2004), To Rescue a Starving Horse