AMBULATORY PRACTICE


gums but also lack of salivary bathing time and hormonal influences. Reducing food stasis is very important in prevent-


ing periodontal disease. Preventing dental inter- locks and promoting normal movement of mastication aids in the bathing with saliva.10 Ac- cording to Gieche,10 horses rely on normal salivary bathing of the periodontium and continual move- ment of food matter through swallowing. By in- creasing pasture or grass hay, an increase in masticatory time will be instituted. We are hy- pothesizing that the lack of grazing time will not allow the horse to have the head down in proper position to allow the saliva to have the full effect of bathing the incisors and removing stagnant feed. The associated evidence of endocrine disorders


with accompanying laminitis has been studied as to the mechanisms involved.11 With the equine met- abolic syndrome (EMS) present in several horses, it is possible that the glucose and insulin levels in the blood are much higher and may be associated with the periodontal disease that was present in these horses. In several studies, as will be discussed, the end results of EMS on laminitis include vasocon- striction, thrombosis, and catabolism of laminar pro- teins.12 All risk factors should be considered with the anatomical structures around the tooth. It has been found that the tooth actually fits into a fibrous socket called a gomphosis.10,13 The joint consists of cementum (which is a living tissue),14 periodontal ligament, bone lining of the alveolus, and gingival that is facing the tooth. In small animals, recent research indicates that there is a much higher prev- alence of ligament laxity with associated canine Cushing’s disease, presumably because of the hor- monal effects of cortizol.15 It has been widely ac- knowledged that horses with pituitary pars intermedia dysfunction (PPID) and EMS are much more predisposed to infection. It is hypothesized that horses with clinical signs of PPID, EMS, and laminitis may be more at risk for development of EOTRH. The hormonal effects of cortizol may weaken the periodontal ligaments, and the high lev- els of glucose and insulin in the blood may affect essential components of the cementum and peri- odontal ligament adversely, thereby increasing the risk of periodontal disease. The risk factor of horses that have been diagnosed with hormonal dis- eases such as PPID and EMS with associated lami- nitis are hypothesized to be of significant value.


2. Materials and Methods


We used detailed medical records on more than 13,000 veterinary calls involving 3461 horses over a 12-year period for an equine veterinary group lo- cated in the desert southwest to conduct an archival study that matches the statistical characteristics of a prospective, repeated-measures, longitudinal field study. Horses were included in the analysis on the basis of having been visited by a veterinarian in the group for any reason from 2000 to 2012. Horses


Table 1. Examples of Terms Used in Content Analysis of Medical Re- cords


Variable


Low-mastication feed


Endocrine


External/behavioral symptoms


Example Key Terms


Excessive dentistry Lay dentist, incisor reduction Dental disease


Periodontal disease Alfalfa, not pasture, not grazing


Cushing’s disease, PPID, Prascend,b crested neck, EMS, metabolic syndrome, fatty deposits, laminitis


Excess salivation, drooling, mouthing water bucket


were then followed at each subsequent visit by any vet in the group for the duration of the study period or until the horse was no longer a patient. Content analysis was used to code the notes attendant to each visit for key terms indicative of the outcome and risk factors, as illustrated in Table 1. Risk factors were age, breed, sex, lay dentist, incisor reductions, pasture history, PPID, EMS, presence of periodontal disease, signs of involvement with water (playing, standing by the water tank, etc), saliva- tion, laminitis, and the exclusive history of feeding alfalfa.


Control variables, such as age, breed, and sex,


were coded from extant fields in the veterinary group’s database. We then performed logistic re- gression analyses to test for the predictive relation- ships between risk factors and outcomes entailed in our hypotheses. For the regressions, we restricted our analyses to horse-visit records up to and includ- ing the first incidence of the outcome and used sta- tistical corrections for the non-independence of observations inherent in any repeated-measures design. To gain further insight into and validate the mea- surement of the outcome in our prospective study, we also conducted a retrospective study on 20 cases in which the outcome was identified. This study involved a clinical examination, radiographs before tooth extraction, and a questionnaire given to the horse owners. The clinical exam included exami- nation of the teeth, evaluation for regional adiposity, presence of long haircoat, and overall body condi- tion. When evidence of EOTRH was present, radio- graphs were advised, and those patients in the study had radiographs taken before surgical tooth extrac- tion. The questionnaire involved 16 questions cov- ering the risk factors, symptoms, and history items revealed as important in the statistical analyses.


3. Results


Our sample consisted of 3461 horses, ranging in age from 1 to 40 years, covering more than 70 breeds and with a mix of mares, geldings, and stallions. The average age was 9.3 years. Nearly a third of the sample were Quarter Horses, with another fifth be-


AAEP PROCEEDINGS  Vol. 59  2013 67


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