Disease Du Jour: Feeding the Thin or Rescued Horse

In this episode, Dr. Clair Thunes discusses feeding recommendations for horses that are thin and horses that have been starved.
thin horse in field
Thin horses that are being fed enough calories might have an underlying pathology that needs to be addressed. | iStock

Most equine practitioners will encounter thin horses that need to gain weight, and some veterinarians might even work on emaciated horses that have been starved. In this episode of the Disease Du Jour podcast, Clair Thunes, PhD, a private equine nutritionist, offers feeding recommendations for thin and starved horses. 

Reasons Why a Horse Might be Thin

Thunes started by discussing some of the underlying reasons for why a horse might be underweight. “The basic concept is that calories in need to equal calories out. When I body score a horse that needs to gain some weight, I look at the diet and see if this horse is actually being fed the calories it needs,” she said. “If the horse needs 25 megacalories per day and its being fed 35 per day and is still underweight, then my brain goes, ‘What’s going on? Why is this horse underweight?’”

If the horse’s calorie requirements are being met, Thunes considers potential causes such as parasites, digestive tract issues, gastric ulcers, hindgut disruption or PPID. She also considers the quality of the feed and hay. The teeth are another potential concern. 

“Just because [the horse’s teeth] were done six months ago, doesn’t mean that they don’t need their mouth looked at again,” said. “Something could have happened. They could have cracked a tooth. Some horses need dental more frequently.”

Thunes said pain is another consideration when working with an underweight horse. She discussed a horse she knew in its late teens who rapidly dropped more than 100 pounds in a short amount of time. That horse was PPID-negative and had normal CBC and metabolic panels. Then, the vet decided to perform a lameness exam and diagnosed the horse with hock pain. They put the horse on pain medication, and it started gaining weight again. “Pain is a big stressor, and that can really cause you to burn calories,” she said. 

Refeeding Starved Horses

Thunes then moved on to discussing starved horses, which can be defined as horses that have not had anything to eat for at least five days, or horses that have lost more than 15% of their body weight in the previous 60 days or less and that have no other unassociated problems. These horses need to be refed carefully. “You can literally kill them if you do it wrong,” Thunes said.

Thunes discussed the refeeding protocol developed by UC Davis, which recommends using alfalfa due to its low starch and carbohydrate content, as well as its high magnesium and phosphorous content. According to this protocol, you should start by feeding the horse one pound of alfalfa every four hours for the first one to three days. On days four through 10, you can slowly increase the amount of alfalfa and decrease the number of feedings until you are feeding four pounds of alfalfa every eight hours. After day 10, feed the horse as much alfalfa as it will eat. 

Thunes also mentioned another refeeding protocol developed by McIntosh et al., which uses grass hay instead of alfalfa. This protocol recommends feeding two pounds of grass hay every four hours for the first three days, and then slowing increasing to eight pounds every eight hours on days four through seven. Continue at that rate until date 14, and slowly increase from there. 

Thunes would not recommend using any commercial feed for starved horses for at least two weeks. Starved horses should also not have a salt block for the first two weeks. It is very important to avoid spiking these horses’ glucose levels. 

Feed Recommendations for Underweight Horses

Thunes concluded the discussion with feed recommendations for underweight horses. 

“When I go to commercial feeds, I gravitate towards high-fat, high-fiber feeds and stay away from high-starch feeds,” she said. She likes to use senior feeds, which can be more digestible, often include beet pulp, and tend to have a fat content around 10-12%. 

Thunes noted that it is important to read the feeding directions. Some of these feeds are meant to be complete feeds and need to be fed in higher amounts to meet the horse’s nutritional requirements. 

Thunes also likes to use alfalfa hay in the diet if the horse can eat it safely (it would not be recommended for a horse with renal problems, for example). Alfalfa is higher in calories per pound and higher in protein. It is also palatable for picky horses. 

About Dr. Clair Thunes

Clair Thunes,PhD, is an equine nutritionist who owns Clarity Equine Nutrition based in Gilbert, Arizona. Thunes works as a consultant with veterinarians, horse owners and trainers globally to take the guesswork out of feeding horses, and she provides services to select companies. As a nutritionist, she works with all equids, from WEG competitors to miniature donkeys and everything in between. Born in England, she earned her undergraduate degree at Edinburgh University in Scotland, and her master’s and doctorate in nutrition at the University of California, Davis.

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