Chicago’s owner knew instantly that something was not right with her horse. He was dull, off his food and sensitive to his jaw being touched, especially over a mysterious, hard swelling that had recently appeared. Jan immediately called her vet.
“I attended and arranged for Chicago to be admitted to our equine clinic later that day, where we ran tests to confirm diagnosis of a suspected apical [tooth root] infection,” says Dr Kieran Rowley MRCVS of Buckingham Equine Vets. “X-rays confirmed an infection of tooth 407, the second premolar, with associated bony swelling. Chicago was immediately started on an antibiotic that has good penetration into bone and a broad spectrum of activity, along with anti-inflammatories to keep him comfortable.
“Apical infection can be caused by a number of conditions, including infundibula decay (cavities), exposure of the pulp chambers on the crown of the tooth, tooth fracture and blood-borne infection,” adds Kieran. “First-line diagnosis involves clinical examination, a full oral examination, preferably with a dental endoscope, and X-rays.
“For the more challenging cases, CT scanning may be required. Segmental CT scans allow the creation of a three-dimensional image of the horse’s skull, as an aid to diagnosis and treatment.”
Treatment can vary, explains Kieran, depending on the cause of the infection and the specifics of each case.
“Antibiotics are commonly used, but treatment failure is quite common and further treatments may be required,” he says.
“If the tooth has fractured or there is severe periodontal disease — gum inflammation and infection — extraction is the only possibility. In select cases, however, it is possible to replant the tooth back into the mouth after the infected material has been removed.”
Fighting infection
Initially, Chicago responded well to treatment. It quickly became apparent, however, that the infection would not clear up with antibiotics. It was decided that the tooth needed to be extracted, to remove the source of infection, but could it be replanted?
Dr Chris Pearce, a European and RCVS specialist in equine dentistry and director of the Equine Dental Clinic, performed the replanting procedure.
“Chicago was sedated and standing in stocks while the tooth was extracted,” explains Kieran. “Chris then prepared the tooth for replanting, which involves removing the necrotic [dead] and live pulp, disinfecting the tooth and filling the pulp chambers with dental cement. The tooth was then placed back into the alveolar socket from which it was removed.”
Chicago was closely monitored for any signs of complications, such as difficulty eating or ongoing infection, but made a quick recovery.
“Follow-up X-rays were scheduled to monitor the replantation, at one, three, six and 12 months,” says Kieran. “Six months after the initial presenting signs, Chicago was out competing without any evidence of oral pain and no bitting problems.”
A way forward?
The technique of extracting and then replanting equine teeth is still very much in its infancy. It’s a complex process, not suitable for every horse and not yet widely available, but it does indicate one direction in which equine dentistry is heading.
“Most equine dental problems are treated by tooth extraction,” says Chris. “In the horse this is a fairly big surgical procedure which leaves a large hole, although this usually heals well.
“While the procedure is not without its risks, complication rates are now much lower than they used to be — especially as the procedure can now be performed under standing sedation rather than general anaesthetic.
“Once the tooth is out, however, problems can begin. The horse’s chewing action is reduced and the whole mouth can become unbalanced as neighbouring teeth shift forwards to close the gap. Because the tooth opposite the gap is unopposed, overgrowth can occur if the horse does not receive good, six-monthly dental treatment. Food can become trapped in the gap as it narrows over the years, causing periodontal [gum] decay.
“In Chicago’s case, the tooth was dead and had to be extracted when antibiotic treatment failed to control an underlying infection. When infection occurs, the tooth can become irreparably damaged. From the outside it looks no different but it is dead inside, hiding a reservoir of infection that causes the tooth to rot from the inside out.
“At this point a quick decision has to be made: whether to extract the tooth and leave a hole, with the associated problems, or whether to attempt a tooth-saving treatment.”
Break point
“At the moment, we don’t know how long a replanted tooth will last,” Chris continues. “The tooth is not technically alive and is not receiving any nutrients from the pulp system, so it will become progressively more brittle. After around six years it will most probably fracture at the root end, but this does give the horse some years of comfortable work in the meantime and protects the teeth from displacement.
“The idea of replanting may be in its early stages, but ongoing findings are due to be presented at the international European Veterinary Dental Forum (18-20 May 2017). It’s important that owners realise that leaving teeth to decay is not an option; early diagnosis and prompt action can mean that a procedure such as replanting is a possibility.
“Extraction is hugely preferable to leaving a diseased, dead tooth in the mouth, however, and continues to be the best option in many cases.”
Ref Horse & Hound; 5 January 2017
