Old Exclusive
Published in modified form in EQUUS magazine A leggy bay colt was born on the hallowed Kentucky grass early in 1985. Named Old Exclusive, as a 17 hand, 2 inch tall three year old, he found his way to the Southern California Racing Circuit where he broke his maiden and won a Stakes race at Del Mar. Shortly thereafter Bob St. Cyr and a partner claimed Oldie for $32,000 at Hollywood Park in the winter of 1988. He went on to compile close to $100,000 lifetime earnings, winning 5 of 11 starts, and only finishing out of the money twice before he was retired to stud at 6 years of age.

Oldie was bred to a few mares and his babies have graced dressage arenas as well as the race track. In 1996, Bob and his partner gave Oldie to Bob’s wife, Sue Wells, and she had him gelded so that his new career as a riding horse would be a little less of a challenge.

Sue and Bob moved with Oldie to the beautiful country of Southwestern Colorado, in 2005, so that he could spend the rest of his days grazing in pasture and meandering with Sue on nearby trails. The long transport from California was disastrous. Oldie’s head was tied high and when he developed a respiratory infection, he could not drop his head to cough or clear the secretions from his throat. Oldie was frantic when he got off the van. I first saw Oldie for a hind leg wound he’d incurred during the trip. Since then, Oldie has not been fond of trailers.

That injury resolved but Sue later mentioned to us that Oldie tended to slobber when eating his senior concentrate and was having trouble gaining weight. He’d had a dental exam at his prior stable within the last few months.

My husband and partner, Dr. Jim Latham, took a look at Oldie’s mouth. He did not have any apparent sharp points, hooks or waves, and the only findings were hyperemic gums (red and slightly puffy just above the incisor teeth), a few petechiae (tiny red dots that represent inflammation) above the incisors on the gums, and one chronic, healing ulcer above the middle upper incisor on the left. We probed the ulcer a bit, and then prescribed a diluted chlorhexidine rinse to use on the gum tissue to reduce contamination and inflammation. The rinse is similar to a chlorhexidine rinse used in human dentistry. We also pulled a blood sample to check body function on this older horse in case kidney disease was responsible for the gum ulcers and petechiae.

Oldie also wasn’t eating his grass hay very well. This retired race horse was used to alfalfa and massive amounts of grains. We changed his forage to 50% alfalfa suggested a blanket in the cooling Colorado nights for the thin skinned, finely haired old campaigner.

A recheck two weeks later showed reduction of the gum inflammation and Oldie seemed stable. The blood work had been normal. Oldie had another fairly common thoroughbred issue—he made noise when he took deeper breaths.

In the middle of the winter, Oldie went off feed and the left side of his jaw was swollen and painful with a wound draining pus. We sedated Oldie to take jaw bone x-rays and get a better look at the back of his mouth. We learned quickly that the big thoroughbred was fairly resistant to routine doses of sedation. Culture of the wound disclosed a pure growth of the bacteria, Streptococcus zooepidemicus, one of the more common equine pathogens, and the x-rays did not disclose any bony damage to the mandible (lower jaw). The wound was flushed twice daily, Oldie condescended to eat crushed pills of trimethoprim sulfa antibiotic in his senior concentrate, and with Bute, he felt better right away. The wound reduced in size and drainage, and ultimately closed. We surmised that the wound had been caused by a puncture.

Having been gelded at age 11 after several years of standing at stud, Oldie had many of the learned behaviors of a stallion. He was frustrated when mares nearby cycled and when spring came around, Oldie had a tendency to rear over pipe corrals and cables. He fought with other geldings, and managed a few injuries here and there. He needed the company of a mare and separating him for travel or confinement was difficult.

By spring we scheduled a routine dentistry. Once again we noted Oldie’s relative resistance to sedation, but managed to correct minor deviations in his cheek teeth. His lower cheek teeth were especially worn. Most significantly, however, the intermediate incisor on the left upper arcade had a fractured piece in the middle of the tooth and two fistulous (draining) tracts through the gums into the roots of the tooth. We removed the fractured piece, flushed the tracks and discussed extraction of the tooth. Within a month, we x-ray’d Oldie’s incisors and additionally used our endoscope to diagnose left laryngeal hemiplegia, grade III.-- Oldie was a “roarer” and yet he’d run like the wind.

The dental x-rays demonstrated lysis (holes) in the center of the tooth as well as proliferation of the cementum in all of the upper incisors except the central incisor on the right. As well, there were resorptive changes in the incisor roots and loss of alveolar bone, especially around the left corner incisor root. His corner incisor teeth were bulbous and roughened like cauliflower. We advised immediate extraction of the left intermediate upper incisor and advised that there would be additional extractions in the future.

Bob and Sue had serious reservations about transporting Oldie, but within a month, they arranged to bring him in to our clinic. After sedation, a maxillary nerve block, and local anesthesia, we extracted the damaged intermediate incisor, removed devitalized bone with rongeurs, flushed the fistulous tracts and saved the bone and abnormal root pieces for culture. The bad news was that both upper corner incisors were developing periodontal fistulae as well. Oldie went home on antibiotics and pain reliever.

Oldie reacted to the oral antibiotics we had prescribed, becoming depressed and off feed, so we began an injectable antibiotic, gentamycin, and asked Sue to continue to flush the gums and socket where the tooth had been extracted with diluted chlorhexidene. The gums healed. On consultation with equine veterinarians in primarily dental practices, we made the diagnosis of chronic incisor periodontal disease, known first as hypercementosis. At the 2006 AAEP meeting, 4 cases of the disease in older horses were described by Dr Robert Gregory from Washington. In all 4 cases, the cementum was lytic in some areas and hyperplastic in others, as a response to inflammation, and the disease seemed to progress from the corner incisors towards the middle.

The external surface of the equine tooth is covered by cementum overlying enamel. The cementum also extends down into the infolded infundibulum (cup) in the center of the tooth. Some live cells of the tooth called odontoclasts cause lysis, literally eating away, of cementum both inside the infundibulum and in the cementum and tissues surrounding the tooth. Other cells respond to inflammatory insult by creating extra cementum (hypercementosis) that eventually extrudes the tooth and root from the underlying alveolar bone. The more severely affected teeth develop infection that may break through into the pulp leading to death of the pulp tissue.

Unknown Cause
Research to determine the cause of the inflammation is ongoing. Carsten Staszyk at the University of Veterinary Medicine in Hannover, Germany, believes that as horses age the angulation of the incisor teeth puts additional stress on the periodontal ligament leading to inflammation that triggers this syndrome that he now labels Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH). Additionally, many different bacterial organisms have been cultured from extracted teeth and surrounding tissue, but there is still not a clear etiology. Dr. Ed Earley, Fellow of the Academy of Veterinary Dentistry, from Williamsport, PA, continues to gather tissues and teeth for examination and culture.

Historically, treatments have included antibiotics, pulsed antibiotics (once a month, for 5-10 days) steroids injected around the teeth when the lesions are early and only hyperplastic, and extraction of all loosened, or badly infected teeth. Most veterinarians consider the disease very painful when it reaches the lytic stage, especially if the teeth are loosened and mobile. (Affected horses may refuse the bit, become head shy, or turn away from apples, carrots or treats). Splinting of remaining teeth with acrylic materials may be done to reduce mobility and subsequent pain. Full extraction has made some horses more comfortable and a gingival flap procedure to suture the gum tissue over the extraction site may speed healing.

We have continued to monitor Oldie’s periodontal disease and have recommended extraction of all involved teeth under full anesthesia at a referral hospital. Oldie seems to be almost rejecting his teeth as the roots are exposed on some, and the interior of some teeth contain a thick, mushy material. The mandibular (lower) incisors are now involved as well.

Sue and Oldie (bottom) on the trail
However, considering Oldie’s age and his extreme anxiety in a trailer, his owners are reluctant to haul a minimum of three hours for the work. Oldie is contented to share his hillside paddock with 19 year old girl friend, Fox, and the big gelding will bite carrots and appreciates his daily gum flushing with chlorhexidine rinse. He does not maintain weight well, however, on hay and pasture alone, so the amount of senior feed in his diet has steadily increased. His owners are starting to notice Oldie displaying some discomfort from his mouth. Though he does not hesitate to eat or drink, he will occasionally toss his head suddenly, like he got a “zing” in his teeth. Flushing his teeth regularly, and administering low doses of Bute on occasion seem to help. His owners also follow the recommended pulsing of antibiotic, now an oral form called doxycycline. monthly. With increased doses of sedative, local anesthesia and regional blocks, it looks like we should be removing more diseased incisors one by one.

Increasing numbers of cases of EOTRH (chronic incisor periodontal disease) have been recognized and the disease is now considered to be fairly common in aged horses. Veterinarians are looking for a successful early recognition and intervention to slow the progression of the disease.

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