Dental disease is certainly a problem in older horses as many of them have fewer teeth; some have fallen out or were extracted, thus making chewing difficult.  Also, there is a problem that affects mostly the incisors or front teeth in horses, a disease called EOTRH that stands for equine odontoclastic tooth resorption and hypercementosis.  You can see why the acronym is used when referring to this disease.  But the main issue is the teeth begin resorbing and excess cementum is produced on their root.  As the condition progresses, the teeth become inflamed, infected and painful, which can lead to a decreased appetite.  This disease affects the front teeth. Horses graze by grasping grass with their front teeth and tearing it off, so horses with EOTRH may not be able to graze because of the pain, so they will lose weight. 

If they can’t graze, then hay is the best forage option. Underweight horses need at least two percent of their body weight per day in forage, which is about 20 pounds for a 1,000-pound horse.  The staff at Kentucky Equine Research says that long-stem alfalfa is a good option for underweight horses because of its higher protein and energy content; a soft leafy alfalfa works best for horses with dental disease.  If you are going to feed hay cubes, first soak them long enough to soften them.  Some of these horses will require a complete feed that does not require any forage. Adding vegetable oil to the diet can add extra calories without the risk of founder or colic. 

Lastly, horses with EOTRH need to have their teeth x-rayed by your vet as some may need to be extracted to decrease the pain.  If your horse’s front teeth appear abnormal at the gum line, call your vet for an exam.