Re-Feeding Syndrome and the Starving Horse
TOPIC
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 {the backbone is
prominent but fat covers to the midpoint, slight fat layer over the ribs, tail head is evident, withers, shoulders and neck are emphasized (Henneke,
1983)}, 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.
MANAGING AND REFEEDING A STARVING HORSE
When re-feeding a starving horse some important points to remember include:
- Re-feeding syndrome usually occurs within the first 3 to 7 days.
- The recommended diet is high-fat and low carbohydrate. Phosphate, magnesium
and potassium levels must be adequate.
- Alfalfa hay is recommended.
- The best approach is frequent small meals of high-quality alfalfa. The frequency
should be decreased gradually and the amount fed increased gradually over a 10
day period.
- After 10 days to 2 weeks the horse can be fed as much as it will eat. Researchers
feel that this time period is critical for the successful transition of the gut from a
starved state to a fed state.
- The energy level of the horse will increase in about 2 weeks. Animation of the ears, eyes and head will be the first noticeable movements.
- Three to five months is the expected time frame to restore and rehabilitate the horse back to its normal weight.
Careful monitoring of the horse is essential during the re-feeding process. Serum electrolyte levels should be checked at least every 24 hours for the
first 5 – 7 days.
Starved animals have impaired immune systems so they should be separated from other animals.
Physical symptoms to monitor for re-feeding complications include: muscle weakness, neurological dysfunction {including weakness, seizures, coma},
and cardiac dysfunction. Hypomagnesaemia can produce irritability or aggression in the horse and hypophosphatemia can cause hemolytic anemia.
Electrolyte imbalances may need to be corrected with fluid therapy if any of these symptoms are noted.
Because starvation impacts the renal and cardiac function, complications may also include excess fluid levels in the body. This condition can be
further complicated by the increased insulin levels which, in turn, cause a reduction in sodium and water excretion.
Another possible re-feeding obstacle concerns thiamine. Thiamine is involved in carbohydrate metabolism so, the resulting deficiency caused by
starvation may be aggravated by carbohydrate re-feeding. If this occurs the horse may suffer from ‘Wernicke’s’ syndrome which may cause ocular
disturbance, ataxia or coma. Thiamine supplementation should be provided. Because oral absorption may be compromised, thiamine
supplementation should be administered by injection.
Other than parenteral thiamine, no other supplementation is indicated during re-feeding.
According to Dr. Carolyn Stull, PhD the re-feeding recommendations are as follows (RioVista Products):
Days 1-3
Feed one pound (@ 1/6 of a flake) of leafy alfalfa every four hours for a total of six pounds per day divided into six feedings. Contact a vet to evaluate
the medical status of the horse.
Days 4-10
Slowly increase the amount of alfalfa and decrease the number of feedings so that by day six, you are feeding just over four pounds of hay every eight
hours (total of 13 pounds per day in 3 feedings)
Days 10 – several months
Feed as much alfalfa as the horse will eat and decrease feeding to twice a day. Provide access to a salt block. Do not feed grain or supplemental
materials until the horse is well along in his recovery; early feeding of grain and supplemental material complicates the return of normal metabolic
function and can result in death.
*Provide clean, fresh water at all times.
*De-worming and correction of dental problems are very beneficial to the horse’s recovery.
TAKE HOME POINTS
Prevention is best defense for starvation:
- Always provide high quality forage equal to at least 1.5% of the horses
body weight. Adjust the amount fed according to the horses BCS. A BCS
between 5-7 is the ideal.
- Analyze the forage fed and provide the appropriate nutrient supplementation for
the horse’s age, job and, activity level.
- De-worm the horse based on fecal egg counts and veterinary recommendations.
- Provide appropriate and regular dental and veterinary care.
In The Event of Starvation or Malnutrition:
- Consult with a veterinarian and a nutritionist.
- Re-feeding syndrome usually occurs within 3 – 5 days.
- The best approach is frequent small meals of high quality alfalfa. Gradually
increase the amount fed and decrease the frequency fed over a 10 day period.
- Feed according to the guidelines set forth by Dr. Carolyn Stull PhD.
- Closely monitor the horse for any complications that may develop during the recovery process.
References:
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
http://www.cvm.umn.edu//newsandevents/facts/rescuehorses/home.html
University of Minnesota, FAQ About Rescue Horses, College of Veterinary Medicine.
http://www.thehorse.com
#5378 January 2005, ‘AAEP 2004: How to Manage Starved Horses and Effectively Work with Humane and Law Enforcement Officials
http://www/thehorse.com
King, Marcia, April 2003, ‘Saving Survivors, Article # 4283
http://www.pleasefeedme.org
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
http://www.horsewelfare.net/glossary
http://www.fresnostatehorses.com
http://www.awionline.org/farm/horses/guidelines.htm#appB
Basic Guidelines for Operating an Equine Rescue or Retirement Facility
Henneke et al, 1983, Equine Vet Journal, pp 371 – 372, Body Condition Scoring
http://www.equinepost.com/resources/articles.asp?ID=3
Dawson, Robert O., Professor of Law, University of Texas School of Law
(March, 2004), To Rescue a Starving Horse
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Jan 3 ReFeeding syndrome in horsesposted by helyn on 03.01.10 21:00 as Yes, winning is not everything.
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