Feeding the “good doer”

Overview

The term “good doers” refers to horses and ponies that are able to maintain or gain weight on a minimum amount of food. In their natural environment horses would have to make the most of poor quality grazing and would constantly be on the move in search of fresh grazing areas. The majority of horses and ponies are now no longer kept as nature intended.

This change in lifestyle and diet has brought about its own set of problems, namely the challenge of keeping these “good doers” in slim, healthy condition, as they can be prone to obesity, laminitis and metabolic problems. Owners of good doers should regularly perform body condition scoring and modify feeding and exercise to ensure these horses maintain a healthy body weight.

Body condition scoring

Good doers have a tendency to be overweight. Frequently owners will fail to recognise what constitutes a healthy body condition score (BCS). Scoring does not have to be complicated or time-consuming. As a rule of thumb you should be able to run your hand lightly across the ribcage and be able to feel ribs easily but not see them. A horse can be considered overweight if:

• Ribs are difficult to feel even with firm pressure
• The horse has a “cresty” neck
• Withers are rounded, covered in fat and shoulder blades are not easily seen
• The area surrounding the tailhead is bulging and soft
• There is a crease down the centre of the back
• There is fat bulging behind the shoulders and along the inner buttocks

Regular condition scoring and measuring with a weight tape will enable you to detect any changes in your horse’s weight and condition much quicker than by eye alone.

Equine Metabolic Syndrome

Overweight good doers are at risk for developing Equine Metabolic Syndrome (EMS). This syndrome is associated with chronic insulin resistance, obesity and abnormal fat deposits, or "regional adiposity". Regional adiposity refers to the areas of fat accumulation seen in horses with Equine Metabolic Syndrome, such as in the neck, behind the shoulder, at the wither, above the tail head, over the eyes, and in the sheath of male horses. Insulin is a hormone secreted by the pancreas that stimulates the uptake of glucose (sugar) by tissues when glucose levels are high, such as after a meal. IR occurs when there is a failure of insulin-sensitive tissue to respond to insulin. This results in an increased production of insulin in order to maintain (or attempt to maintain) circulating blood sugar levels within normal limits.

Horses with this condition have a higher chance of developing laminitis or ‘founder’ (inflammation of the sensitive laminae in the horse’s hoof) than other horses. Therefore it is also important these horses receive regular and appropriate foot trimming. Although there is a strong genetic influence to EMS (certain breeds do seem to be predisposed to this condition), obesity is the primary problem that sets off the cascade of metabolic abnormalities. A horse is diagnosed with Equine Metabolic Syndrome through physical appearance, routine blood tests, and specific insulin and glucose tests. There is no specific treatment or cure for horses with the syndrome, thus treatment is aimed at altering the horse’s diet and instituting a strict exercise regime.

Diet

The basis of any horse or pony’s diet should be fibre and the equine digestive system is well designed for this diet. In their natural environment horses and ponies will spend up to 18 hours a day grazing. For most horses not involved in moderate to heavy work, forage alone (grass and/or hay) can meet their dietary needs. A healthy adult horse requires 1.5 to 2.5% of their body weight in hay per day. Good doers generally require only 1.5% of their body weight in hay each day. So a 500kg good doer only needs 7.5kg of good quality hay daily. It is essential for a horse's mental and physical health that it gets enough fibre especially when limiting calorie intake.

Horses are designed to spend the majority of their time eating and hours without food can result in a bored horse and behaviours such as wood chewing, cribbing. At worst, without the bulk material required by the horse’s digestive system, a horse can develop colic. It is important that you have in place a balanced nutritional program suited to your horse’s exercise level that keeps your horse from getting fat and provides the necessary fibre in the diet. There are many ways to lower your good doers’ calorie intake or slow their consumption:

• Using a grazing muzzle when turning a horse out to graze can slow their intake, but first make sure the horse can drink while it is on.
• Strip graze large grass paddocks or fence off a smaller “starvation” paddock for your horse.
• Soak hay in clean water for at least an hour to leach out sugars, this lowers its energy content but still provides plenty of fibre for a healthy digestive system.
• Slow down the rate your horse eats hay by using 2 small haynets, one placed inside the other or using one with very small holes.
• Feed low energy chaff.
• Divide the daily forage allowance into several smaller meals so that your horse does not have to go long without food. The horse shouldn’t be left overnight or longer than 8 hours without food as this can predispose them to colic.
• Eliminate grain and other concentrated and high-sugar feeds.
• Limit pasture access in some way during the spring and autumn when the grasses tend to be highest in their sugar/starch content.
• Restrict your horse's pasture access in early to mid morning and again in mid to late afternoon as this is when peak production of fructan sugars in grass occurs.
• Weigh your horse’s hay rather than simply ‘guesstimating’. This is an integral step to avoid overfeeding.

Horses and ponies that are working harder may need additional feed to provide extra energy. However, it is important to remember if you are feeding a high energy feed your horse will be receiving a high number of calories and unless these extra calories are being used for work they will be used for weight gain instead. Often horses or ponies that are lacking in energy are overweight and unfit and feeding a higher energy feed will only exacerbate the problem. In these cases, a gradual fitness program combined with a high-fibre, low-calorie diet should be implemented, which should result in a slimmer, fitter horse who finds work easier. The high-fibre, low-starch, low-sugar diet is also a more natural feed for the horse’s digestive system and helps to avoid digestive problems such as colic and laminitis which can be linked to high-starch, low-fibre diets.

Horses usually do not require nutritional supplements if they are fed good quality hay. Nutritional supplements are widely considered safe; however, be aware that you can over supplement your horse. Remember that horses can experience gastrointestinal problems secondary to sudden dietary changes, so make any changes to a horse’s diet slowly over the course of several days, even if you’re eliminating components. All horses should be offered free choice water.

Weight loss

Weight loss should occur gradually over the course of several months. A horse may safely lose about 20kg or one body condition score each month. Rapid weight loss, especially in obese ponies, may put the animal at a high risk of developing hyperlipaemia. Hyperlipaemia is a condition where the body perceives itself to be starving, leading to the release of large quantities of stored fat into the bloodstream. This condition may quickly lead to impaired liver function and death. Signs of hyperlipaemia include drowsiness, depression, muscle twitching, poor coordination, colic, and diarrhoea. Another drawback to intensive weight loss strategies is the increased likelihood of developing stereotypical behaviours. Allowing horses to interact with field companions, the provision of stimulatory toys, and the use of a regular exercise program may reduce the likelihood of stereotypies such as weaving, pacing, wood-chewing, bedding ingestion, coprophagy and cribbing. 

Proper weight loss may take several months, body weight and body condition score changes should be monitored every 2- 4 weeks. Monitoring too often (i.e., weekly) can cause the horse owner to become discouraged because visible changes may not be readily obvious. Taking photographs of your horse every few weeks is a good way to see the positive effects of a weight loss programme. Patience and consistency are key, once the horse has reached its ideal body weight or BCS, maintaining that level of fitness is critical. Constant attention to the quality and quantity of feed offered as well as the body weight and body condition score of the horse will allow horse owners to make informed decisions as to the amount of feed offered to the horse. Adjustments to the ration can be made based on the changing requirements of the horse during the different seasons or training schedules. Some fluctuation of body weight is normal in the adult horse.

Exercise

Exercise is important to keep any good doer in trim and healthy condition and it is essential for overweight horses or those with EMS/IR. Horses must be introduced into exercise gradually and should never be pushed beyond their physical capacity. This is especially true for overweight horses because they are more prone to fatigue and injury due to carrying excessive amounts of weight. Workload should start slowly and over several weeks the length of time and intensity can be increased. It is important to remember that turnout does not equal exercise.

To enable your horse to lose weight will involve daily or near daily exercise, either ridden, in-hand or lunging. If it is not possible to immediately implement an exercise regime (if the horse is suffering from a laminitic episode, for example), institute the dietary changes first and then begin an exercise regimen.

Additional information

Your veterinarian should be happy to discuss a feeding and exercise plan and any concerns you might have regarding your horses weight. Most feed companies also have feeding help-lines that offer practical, easy to understand advice.

Dr Rachel O’Higgins

This content was originally published by Equine Veterinarians Australia (EVA), a special interest group of The Australian Veterinary Association.