RMR August 2011 Article - Dental Analysis of Old Horse's Teeth

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A Dental Analysis of an Old Horse’s

Chewing Problem

Story & Photos by Natalie Riehl, Editor

August 2011 issue

When our 23-year-old, black mare, Raven, had her teeth floated, it did not stop the excessive amount of saliva she had been generating when she ate a ration of oats. She left a pool in her grain bucket, which got worse after she had the “ramps” on her rear molars filed off. She also had trouble chewing her hay; sometimes it clumped up into wads.

Fortunately, she is of hardy stock and managed to maintain her weight even though she was having discomfort.

We asked Dr. Dick Richardson, DVM, of Blue Mountain Veterinary Hospital in Missoula , MT , to give us his opinion. He noted that there was a gap between her upper and lower incisors (front teeth), and that it was not possible to move her jaw from side to side about a tooth’s width, which would show adequate lateral movement on the grinding surfaces of the molars. Puzzled as to what was causing the chewing discomfort problem, he recommended an x-ray of the horse’s jaw and teeth.

Raven has a gap between her top and bottom incisors. X-rays will reveal if this gap is caused by high teeth in the back of her mouth.

Possible problems included a bad tooth, the angle of the teeth’s chewing surfaces, or arthritis in her temporomandibular joint (where the jaw is “hinged” to the skull).

At the clinic, he and his assistant, Amanda Duncan prepared Raven for the x-rays by giving her a tranquilizer. The first image was of her left jaw.

Overall, Dr. Richardson thought her mouth looked good for an aged horse. The left jaw showed no abnormalities, with the teeth evenly worn.

However, the image of the right jaw showed that the upper first molar was shorter than its neighboring teeth, and had large periodontal spaces (known as “diastema”) surrounding it. These spaces around teeth are a phenomenon of aging that is found in horses, as well as humans. “You don’t see young people using toothpicks, do you?” asked Dr. Richardson.

He next checked for arthritis in the temporomandibular joints, but the x-rays did not show any abnormalities or obvious arthritis.

Dr. Richardson explained: “As horses age, the teeth get shorter. This diastema-forming tooth has worn prematurely. This is not a situation that can be cured by floating. I would not recommend pulling the tooth.”

So what was the cause of Raven’s excessive salivation and discomfort when chewing? The answer was not clear. However, in the good news department, it was not a tumor, an abscess, a fractured jaw, a rotten tooth, nor severe arthritis.

(Top)The x-ray of left jaw shows her teeth to be straight and in excellent condition.

(Below)The x-ray of the right jaw shows an abnormal tooth – the upper first molar. However, the x-ray does not reveal an abscess or other obvious problem surrounding the tooth.

He did not recommend taking her to an equine dental specialist to have the spaces around the abnormal tooth made larger because she did not have severe periodontal disease or an abscess. These would have been evident by pain, heat, redness, and a strong odor, and would have shown up on the x-ray.

Dr. Richardson recommended trying injections in the temporomandibular joints with the steroid, methylprednisolone acetate. If she improved with this treatment, he thought she could get injections two times per year.

This treatment has helped the mare greatly. She is no longer salivating to the point of slobbering when she eats her grain.

The injections have allowed her to chew more comfortably, but they have not completely solved the malocclusion. Even though she still has a gap between the top and bottom incisors, Dr. Richardson says, “She holds her jaw this way because it is the most comfortable for her. Even though the gap is not normal, you might cause more problems by drastically changing her mouth.”

Raven receives a steroid injection in her temporomandibular joint.

Also, I had always thought Raven to be head-shy from having been mishandled at some time in her past. She would jerk her head away if we reached out a hand in the direction of her head. However, now that her jaw and teeth do not hurt, she is no longer flinging her head back to avoid our touch.

She has been ridden in a bitless bridle, and she seems to be quite comfortable. She still loves her “treats,” and comes willingly for apples, carrots, and pellets.

For the time being, Raven’s teeth-related problems have been relieved. We will keep a close eye on her, and notify the veterinarian should the symptoms return.

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