Keeping a close eye on your horse's body condition and weight is perhaps the best way to gauge the effectiveness of a feeding program. We all want our horses to be in tip-top shape, well-muscled, and neither too fat nor too thin. The problem? Just what is the ideal body condition (and weight) for a horse, and how can body condition be reliably assessed? Guesswork won't do the job. Even experienced horse owners tend to grossly underestimate body weight when using the "eyeball method." Similarly, subjective assessment of condition using descriptors such as "good," "fair," and "poor" leaves too much room for error. Ideal condition in the eye of one owner might be too fat or too thin to another.
Therefore, we need a more accurate and reliable method. Measurement of body weight (using a scale) is a good way to monitor condition in an individual horse, but the expense of a scale suitable for horses cannot be justified on most farms. A much cheaper approach is to estimate body weight with a weight tape, a system based on the known relationship between girth measurement and body weight in horses. However, although girth measurement does give a reasonable estimate of body weight, studies have shown the numbers can be off by as much as 5%. That's 50 pounds in a 1,000-pound horse!
Another approach is the use of body condition scoring (BCS)--a widely accepted system developed in the early 1980s by Don Henneke, PhD, at Texas A&M University--that has been used by horsemen, nutritionists, and veterinarians. The system provides an estimate of the amount of fat deposited in various places on the horse's body. The beauty of the BCS system is that it is easy to use, requires no equipment, and can be applied to all breeds. You should apply the BCS method to determine if your horse is too fat, too thin, or just right, and if necessary, make adjustments in diet and exercise level to achieve ideal body condition.
The horse's body condition gives a measure of the balance between energy intake and energy expenditure. When energy intake does not keep pace with energy loss, weight is lost. This is reflected in a decrease in body condition (a loss of body fat), which is a negative energy balance. With a positive energy balance--when intake exceeds needs--the horse will gain weight and body condition. Therefore, assessing body fat coverage provides a real measure of energy balance.
Many factors can influence energy balance--the most obvious is feeding. With too many groceries the horse gets fat, not enough and he loses weight. Other important factors are the level of physical activity (at pasture vs. stalled; heavy training and competition vs. light riding), growth demands in horses less than two or three years of age, and reproductive status (late pregnancy and lactation). Chronic illness (such as heavy parasite burdens) and poor teeth are other possible reasons for weight loss. If there is a loss of body condition not accompanied by a change in feeding and exercise, you should ask your veterinarian to check it out.
We also recognize that when comparing two horses of similar size, feeding program, and level of activity, there can be considerable variation in body condition. Some are "easy keepers." Their condition is maintained on a relatively low caloric intake. Others require what seems to be an excessive amount of food to maintain body weight and condition--the so-called "hard keepers."
This variation might be due to differences in digestive and metabolic efficiency as well as temperament. Nervous types tend to "waste" a lot of energy. Generally speaking, Quarter Horses, drafts, and ponies fall into the easy keeper category, while hard keepers more often come from the Thoroughbred and Arabian breeds. In herd situations, pecking order can also have a major influence on energy balance. Shy animals which are lower in the pecking order might not have the opportunity to eat enough when kept in a herd situation. Genetics might also play a role in whether a horse is an easy or a hard keeper.
Look and Feel
You need to use your eyes and hands to assess fat coverage in the following areas: neck, withers, shoulders, ribs, the back and loins, and tailhead and rump. Then, you will assign an overall score ranging from 1 (poor or emaciated) to 9 (extremely fat or obese). To use this system properly, you also need some basic knowledge of anatomy and bone structure. Here is a description of what to look for in each of the six areas (also see the rundown on the general appearance for each of the nine condition scores in "Determining Condition" on page 96).
Neck--Note the overall thickness. In thin horses, some of the vertebrae can be seen and palpated and the jugular groove is well defined. Fat horses have a thick, "cresty" neck (fat deposited on either side of the neck), and the jugular groove is less defined.
Withers--The withers are formed by the very large dorsal spinous processes in the forward region of the backbone. Assessing this area can be tricky because some horses and breeds have more prominent withers than others, even when in good body condition. Nonetheless, in a moderately conditioned horse (BCS 5), the withers should appear nicely rounded. In very thin horses, the underlying structure of the withers is easily seen and palpated. In obese animals, fat tissue bulges around the withers.
Shoulder--Fat tends to deposit behind the shoulder and elbow area. In very fat horses (BCS 8 or 9), the shoulder lacks definition and tends to blend in with the chest.
Ribs--An emaciated or thin horse will have prominent ribs with little or no fat coverage. At BCS 1, all of the ribs can be seen. With an increase in condition, the ribs become less visible. At BCS 5, the ribs are easily felt but not seen. In very fat horses (BCS 9), it is not possible to feel the ribs.
Back and loins--Here you are evaluating flesh coverage and muscling along the topline. The spine or backbone comprises a number of individual vertebrae; each vertebra has bony prominences (called processes) that project to the top (dorsal) and to the side (transverse). In very thin horses these processes are very prominent, creating a bumpy topline. In better-conditioned horses, a crease or depression develops because of fat accumulation above the transverse processes and alongside the dorsal spinous processes.
Tailhead and rump--Evaluate the base of the tail (the tailhead) and the hip bones. A horse with a BCS between 1 and 3 has a prominent tailhead, some of the individual vertebrae can be felt, and parts of the hip bones also can easily be seen. There is little or no fat tissue in the area just in front of the tail. At BCS 5, some spongy tissue can be palpated, while in fat horses, fat bulges around the tailhead.
Here are a few pointers. Don't be fooled by a long coat, which can disguise poor condition, particularly over the rib area. Late pregnancy mares can be difficult to evaluate because the weight of the foal tightens the skin over the ribs, making the mare appear thinner than she really is.
What is Ideal?
A moderate score, such as BCS 5, is a reasonable target for most horses. At this score, the horse has adequate fat reserves to draw on during times of stress, such as during winter. For performance horses, however, many trainers and horsemen prefer their horses to be leaner (closer to BCS 4) because of concerns about excess weight impairing exercise performance. However, a BCS of less than 4 can contribute to performance problems because of a lack of energy reserves. The best example is the endurance horse required to compete at 50 to 100 miles.
Two studies have investigated the relationship between BCS and completion rate during the Tevis Cup (100-mile) endurance ride. The mean BCS of horses which successfully completed the ride was 4.5, whereas horses which were eliminated for metabolic failure (colic, heat exhaustion, synchronous diaphragmatic flutter or "thumps," or tying up) had a mean condition score of 2.9. Horses at BCS 3 or below have very little in the way of fat reserves. If more energy is needed, the horse will break down muscle protein and use that protein for energy. The end result is a loss of muscle mass and a further deterioration in overall condition.
A condition score of no less than 5 is extremely important in broodmares. Research has shown that mares in moderately thin to fleshy condition (BCS 4-7) will conceive earlier in the breeding season and are at lower risk for early embryonic mortality compared to mares with a BCS less than 4. Also, problems can arise when the feeding program is not adjusted to meet the mare's increased needs during late pregnancy (months nine through 11) and during lactation. In particular, the mare can quickly lose weight during the first three months of lactation. It is very important to monitor body condition monthly during pregnancy and lactation, and to make adjustments in feeding to maintain a BCS of 4-7.
Horses with a BCS greater than 7 are also prone to problems. Fat horses (and particularly ponies) are at greater risk for laminitis. Weight loss is important for prevention of recurrence in horses which have foundered. Carrying excess weight also places strain on the feet and legs, and the insulating effect of fat can lead to overheating problems during the summer months. These horses need to lose weight!
Watch for changes in BCS. In most horses, fat first accumulates along the back and loins (topline), then over the ribs and in the tailhead region, followed by the withers and shoulder, and finally over the neck and between the legs.
Now, a few tips on adjusting feeding programs if your horse is not in ideal condition. Of course, changes in feeding should always be made gradually (over a two- to three-week period), particularly when increasing the amount fed. Also bear in mind that it might take at least two months to achieve a one-unit change in BCS.
For an average-sized horse (1,100-1,200 pounds or 495-540 kg), it has been estimated that each unit of condition score represents about 35 to 44 pounds (15-20 kg); a mere 2.2 pounds (1 kg) of weight gain requires 20,000 calories of digestible energy over and above the horse's maintenance needs. Therefore, you are not going to see changes in a week or two.
For weight gain, rule one is to buy a scale suitable for weighing feed. Start with a good-quality forage, fed at rates of up to two pounds per 100 pounds (45 kg) of body weight (typically 20-22 pounds per day or 9-10 kg per day). If the horse is currently receiving about five to six pounds (2.25-2.70 kg) of a grain concentrate, and you are targeting a one-unit increase in condition score over a two-month period, an additional two to three pounds (0.90-1.35 kg) per day of concentrate is required (providing an extra 3,000-4,500 calories). Again, make changes gradually to avoid digestive upsets.
I also recommend using a higher-fat feed (6-8% fat), so that not all of the additional calories are coming from starch and sugar.
To achieve weight loss, a gradual increase in activity (if the horse is sound) and a decrease in feeding is best. Avoid high-energy forages like alfalfa, and cut the hay feeding rate to 1.5 pounds per 100 pounds (0.6 kg per 45 kg) of body weight. The amount of grain concentrate should be reduced (probably by 50%) or eliminated altogether depending on the horse's level of obesity and activity level. In very fat horses (BCS 8-9), no grain is the best plan. However, because most hays do not provide adequate vitamins and minerals, a vitamin-mineral supplement should be fed.
Get comfortable with body condition scoring and use it regularly every two months). By recording the scores and using that guide with information about feeding, climate, and level of activity, you will be able to do a better job of fine-tuning your horse's diet and maintaining his health.
SIX POINTS FOR SCORING BODY CONDITION
When it comes to ideal equine body condition, beauty is often in the eye of the beholder. For example, endurance horses are usually leaner than show-fit halter horses. Because "fitness" is subjective, equine health care professionals utilize a "Body Condition Scoring" system to talk in relative terms. The hores's physical condition is rated on visual appraisal and palpation (feel) of six conformation points:
A--the amount of flesh or fat covering on the neck,
C--down the crease of the back,
D--at the tailhead,
F--and behind the shoulder at the girth.
Scores range from 1-9, from poor to extremely fat.
Carroll, C.L.; Huntington, P.J. Body condition scoring and weight estimation of horses. Equine Veterinary Journal, 20, 41-45, 1988.
Henneke, D.R.; Potter, G.D.; Kreider, J.L.; Yeates, B.F. Relationship between condition score, physical measurements, and body fat percentage in mares. Equine Veterinary Journal, 15, 371-372, 1983.
About the Author
Ray Geor, BVSc, PhD, Dipl. ACVIM, is professor and chairperson of Large Animal Clinical Sciences at the College of Veterinary Medicine at Michigan State University
POLL: University Equine Hospitals