title: Equine Odontoclastic Tooth Resorption and Hypercementosis: Histopathologic Features.
abstract: Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a painful progressive condition of older horses that involves multiple teeth, including canines and incisors. EOTRH is uncommonly recognized by veterinary pathologists and in some cases may be misdiagnosed as cementoblastoma. The cause is unknown. The goals of this study were to describe the histopathologic features of EOTRH in 17 affected horses from the United States and to increase awareness of this condition. Samples ranged from affected tooth to the entire rostral mandible and maxilla. Affected teeth exhibited cemental hyperplasia and lysis. The marked proliferation of cementum in severe cases caused bulbous enlargement of the intra-alveolar portions of affected teeth. Several teeth contained necrotic debris, bacteria, and plant material in the regions of cemental lysis. All horses exhibited dentinal lysis in at least affected tooth, and several contained necrotic debris in these regions. Endodontic disease was often present with inflammation, lysis, necrotic debris, fibrosis, and/or a thin rim of atubular mineralized tissue in the pulp cavity. Periodontal disease was a common feature that was primarily characterized by moderate lymphoplasmacytic inflammation. Resorption with secondary hypercementosis appears to begin on the external surface of the teeth rather than within the pulp cavity. Distinguishing EOTRH from other diseases requires a complete history that includes the number and location of affected teeth, a gross description of regional hard/soft tissue health, and radiographic findings.
authors.affiliation: Diagnostic Center for Population and Animal Health, Michigan State University, Lansing, MI, USA smedley@dcpah.msu.edu.
authors.forename: R C
authors.initials: RC
authors.lastname: Smedley
authors.affiliation: Large Animal Dentistry, Equine Farm Animal Hospital, Cornell University, Ithaca, NY, USA, and Laurel Highland Farm and Equine Service, LLC, Williamsport, PA, USA.
authors.forename: E T
authors.initials: ET
authors.lastname: Earley
authors.affiliation: Animal Care Hospital, Somerville, TN, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Galloway
authors.affiliation: Salem Valley Veterinary Clinic, Salem, CT, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Baratt
authors.affiliation: College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Rawlinson
mesh_terms: D000818:Animals; D003481:Cuspid / Q000473:pathology; D003739:Dental Cementum / Q000473:pathology; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis / Q000473:pathology*; D006736:Horses; D006936:Hypercementosis / Q000473:pathology / Q000662:veterinary*; D007180:Incisor / Q000473:pathology; D008297:Male; D014091:Tooth Resorption / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*
keywords: dental; histopathology; horse; hypercementosis; incisor; multiple idiopathic root resorption; oral pathology; resorption; tooth diseases