If you’re reading this, you likely have one or more fat horses on your farm. In fact, recent study and survey results show that 30-51% of horses in the United States and the U.K. are overconditioned. Because equine obesity is a welfare issue, it’s important to take steps to get and keep your horse at a healthy weight.

During the University of Maryland’s webinar series, Amy Burk, PhD, extension equine specialist and associate professor and coordinator of the university’s Equine Studies program, offered practical weight loss strategies for overweight horses.

She defined equine obesity as fat accumulation on a horse’s body to the degree that it can cause health problems. On the 1-to-9 Henneke body condition scoring (BCS) scale (where 1 is emaciated and 9 is extremely fat), that equates to a BCS of 7 or higher. Ideally, she said, you want your horse to score somewhere in the 4 to 6 range.

Establishing a Weight Loss Program

For the best chance at success, have a plan before changing your horse’s diet and lifestyle. This includes involving your veterinarian.

“They can help you come up with a plan for your horse that’s specific to your horse’s housing and the type of diet you can offer your horse, and they can help you monitor that,” said Burk.

Then make sure you have a way to measure your horse’s weight. If you don’t have access to a horse scale, a weight tape (which you can usually get free from your feed dealer or cheap from a tack store) will give you a good estimation, said Burk. (Or use The Horse’s online “Adult Horse Weight Calculator.”) Log your horse’s weight and body condition score each month to track progress.

Plan for your horse’s weight loss program to take time. The difference between BCS scores is about 45 pounds for the average 1,100-pound horse, said Burk, and losing one BCS typically takes one to two months. “Weight loss is not going to be a quick process for your horse,” she said.

Finally, evaluate your horse’s current diet and housing so you can identify all the factors affecting his weight. This includes asking yourself questions such as:

• How much pasture turnout does he get, and what’s the pasture’s quality?
• What feed and supplements is he getting?
• Who is he turned out or fed with? If your horse is a bit of a bully, for instance, he might be eating other horses’ feed, said Burk.
• How much exercise is he getting?

Then you’re ready to tackle the main steps to weight control: reducing calories and increasing exercise. Medications offer another approach, but they’re typically reserved for only the most weight-loss-resistant of horses, said Burk.

1. Reducing Calories in the Diet

This is the most important thing you can do for an overweight horse, said Burk, and it starts with reducing the amount of feed you’re providing.

If the average horse eats 2-2.5% of his body weight each day, slowly reduce that figure to 1.5% body weight. If your horse hasn’t lost weight after about six to eight weeks, you can lower his total diet to 1.3% body weight, but don’t go any lower than that, said Burk. She described several ways to control what your horse consumes.

Eliminate concentrates

When taking things out of your horse’s diet, the first thing to remove is concentrate (grain). Burk said these energy-rich feeds are intended primarily for exercising, growing, and breeding horses. If yours is a lightly exercised or pleasure horse, he might not need any concentrates. Rather, you can feed a forage (ration) balancer (so called because they balance out what forage can’t provide, she said) to ensure he’s still getting all the nutrients he needs.

“Forage balancers are low in energy, higher in protein and vitamins and minerals, and you’re feeding them at a really small amount every day (about 1 pound for the average horse),” said Burk. “You can feed a straight forage diet with just a little bit of these balancers or a vitamin and mineral supplement and provide everything you need for your horse—you don’t have to have concentrate in the diet.”

Reduce pasture

“Pasture is a great nutritional source for horses,” Burk explained. “It has water, vitamins and minerals, and protein, but it also has digestible energy that when horses consume too much will cause them to gain weight.”

She recommended putting your horse on a dirt drylot with a hay source or keeping him stalled part of the day to control his pasture access. The problem with the latter option, however, is studies have shown horses can still consume a lot of pasture in little time. “They’re lawnmowers,” said Burk.

Use a grazing muzzle

These popular implements allow your horse to still forage, move around, and socialize with pasturemates while reducing grass intake by 30-86%, said Burk.

Feed a lower-quality hay

Avoid legumes such as alfalfa, and instead look for a mature hay such as Timothy or orchardgrass that has lower energy—they’ll have more stem and seedhead on physical examination. “The problem is they’re also lower in protein and vitamins and minerals,” said Burk. “When you feed a mature hay, you often need to feed a forage balancer, too.”

Offer small, frequent meals

“Another strategy that I think is the coolest way to approach feeding horses these days is to take them back to their roots when they were eating small forage meals over the course of the day,” by way of slow feeders and nibble nets, said Burk. “We’ve domesticated the horse and bring large meals to them … why not make them work for it?”

This tactic not only makes your flakes of hay last longer but also helps buffer gastric-ulcer-causing stomach acid because horses are chewing and salivating more.

Feed low-NSC hay

You can try reducing sugars and starches (nonstructural carbohydrates, or NSCs) in your horse’s diet by feeding low-NSC hay such as bermudagrass or teff. Laminitic, pre-laminitic, and metabolic horses, in particular, require very low NSC levels. Find out if your hay is low-NSC by sending samples off for testing, or simply soak a haynet full of it in a tub of water for 30-60 minutes, then drain and feed.

Soaking “reduces water-soluble carbohydrates such as glucose, sucrose, fructose, and fructans,” said Burk. “It’s a great way to reduce NSC content by as much as 30%.”

2. Increasing Exercise

Burk offered several ways to increase your horse’s voluntary exercise:

• House him in large pasture (at least 2 acres), and separate feed and water sources spatially so he has to work to get to them.
• Add a pasture buddy to encourage play.
• Install a dynamic feeding system with sliding doors that allow horses access to forage from only one side. When one door shuts, they have to walk around a fence to the other side of the feeder to continue eating.
• Create a track paddock, which is a path around paddock filled with hills, logs, and enrichments. You move hay sources around every day so horses have to find them.

Ways to increase involuntary exercise include long hand walks, longeing, riding, exercisers, swimming, and leasing the horse out so someone else can ride him if you’re not able to. Burk recommended exercising horses three to four times a week for 30 to 45 minutes and increasing the intensity of the work gradually.

3. Administering Medications or Supplements

Burk said there’s no good research showing that medications or supplements reduce adiposity (fat levels) in obese horses. Veterinarians might recommend them, however, in weight-loss-resistant horses as a last resort, she said.

Specifically, the drug levothyroxine sodium (Thyro L) has been shown to be effective at inducing weight loss and increasing insulin sensitivity in healthy horses but not in overweight ones.

While various metabolic supplements on the market aim to improve insulin sensitivity, Burk said no studies have proven any to be effective at weight loss. There’s no magic bullet, she said.

Take-Home Message

Obesity in horses is a very serious health and welfare problem that owners must address. Its negative impacts include health issues such as laminitis, reduced performance, and financial cost to the owner. Fortunately, you can achieve weight loss through these changes in your horse’s diet and exercise, said Burk.