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Oral Health of Horses: Chewing PainBy Kentucky Equine Research Staff · December 13, 2016

Many of us think first of the teeth when we consider our horses’ mouths—sharp points, hooks, uneven chewing surfaces, erosion, and even lost teeth. Classic signs of dental problems include dropping wads of forage, called quidding, and losing weight due to decreased feed efficiency or even discomfort when chewing. But shouldn’t we take a moment to consider other causes of decreased chewing ability and feed intake?

The temporomandibular joint (TMJ), for example, is among one of the most complex joints in the horse’s body and plays an important role in the so-called “masticatory apparatus.” The joint represents the union of the lower jaw bone, or mandible, with the upper jaw bone, or maxilla. Looking at your horse, this junction of the two bones—the TMJ—is located halfway between the ear and the eye. According to a recent study on the joint*, little is known about its normal anatomy, making diagnosis of TMJ disease or dysfunction difficult. Because it is a joint, arthritis remains the predominant diagnosis for horses with TMJ pain, swelling, and decreased range of motion, leading to the compromised chewing ability.

The muscles and other soft-tissue structures supporting the TMJ joint must also be considered, as well as structures close to the TMJ itself. Further, fractures of any bones involved in the masticatory apparatus must also be assessed when faced with a horse that is reluctant to chew. Fractures of the mandibular rami—the lower jaw bone—also occur and require prompt diagnosis and management, including analysis of any tooth root involvement.

One retrospective study** recently identified conservative management, as opposed to surgery, of mandibular fractures as a viable treatment option, resulting in good outcomes. Conservative therapies included anti-inflammatory medications, slurries rather than hay if the horse seemed unwilling to eat hay, IV fluids for rehydration when necessary, and antimicrobial medications, particularly if an open fracture was identified (i.e., the bone fragments penetrate the skin).

“In general, feeding horses that have difficulty eating due to dental, TMJ, or related pain rather than a neurological or other type of medical abnormality such as choke or botulism, can be challenging and time-consuming,” relayed Kathleen Crandell, Ph.D., an equine nutritionist for Kentucky Equine Research (KER).

“Slurries can be made from a combination of hay pellets and senior feeds that have been softened in adequate water that the horse can slurp up the resulting soup. The hay pellets are important for meeting the horse’s fiber requirements, while the senior feed is a more concentrated source of calories and other important nutrients,” she added.

For any horse having difficulty grasping, chewing, or digesting food and experiencing weight loss, owners can offer EquiShure. This product helps horses maintain a stable hindgut environment, encourages proper digestion and absorption of nutrients, and may improve feed efficiency.

*Adams, K., E. Schulz-Kornas, B. Arzi, et al. 2016. Functional anatomy of the equine temporomandibular joint: Collagen fiber texture of the articular surfaces. Veterinary Journal. 217:58-64.

**Jansson, N. 2016. Conservative management of unilateral fractures of the mandibular rami in horses. Veterinary Surgery. 45(8):1063-1065.