Computed tomographic assessment of equine maxillary cheek teeth anatomical relationships, and paranasal sinus volumes.

Disorders affecting the equine maxillary cheek teeth and paranasal sinuses are relatively common, but limited objective information is available on the dimensions and relationships of these structures in horses of different ages. The aims of this study were to assess age-related changes in the positioning and anatomical relationships of the individual maxillary cheek teeth with the infraorbital canal and maxillary septum and the volumes of the individual sinus compartments. CT and gross examination were performed on 60 normal equine cadaver heads that were aged by their dentition. The intrasinus position of cheek teeth, length of reserve crowns, relationship to the infraorbital canal and measurements of rostral drift and sinus compartment volumes were assessed from CT images. The findings included that Triadan 10 alveoli lay fully or partially in the rostral maxillary sinus (RMS) in 60% of cases. The infraorbital canal lay directly on the medial aspect of the alveolar apex in younger horses. The Triadan 11'sclinical crowns and apices drifted a mean of 2.48 and 2.83 cm more rostral to the orbit, respectively, in the >15 years old vs the <6 years old age group. The mean volumes of sinus compartments ranged from 175 cm3 for the caudal maxillary sinus (CMS) to 4 cm3 for the ethmoidal sinus (ES). This information should be of value in the diagnosis and treatment of equine dental and sinus disorders and as reference values for further studies.

Upper esophageal incompetence in five horses after prosthetic laryngoplasty.

OBJECTIVE: To describe a complication observed endoscopically in horses after prosthetic laryngoplasty (LP). STUDY DESIGN: Case series. ANIMALS: Horses (n = 5) that had previous LP. METHODS: Four horses had endoscopic examination as part of a larger prospective study and had saliva emanating from their upper esophageal opening. One other horse was referred with clinical signs of severe upper esophageal obstruction 2 months after LP. RESULTS: Four horses were observed to have saliva emanating from their upper esophageal opening during endoscopic examination 21-58 months after LP. Esophageal reflux was noted endoscopically at rest (n = 1) and during exercise (4). All 5 horses were reported to cough postoperatively, and 2 horses coughed severely when eating. On necropsy, the horse referred with signs of esophageal obstruction had dilation of the proximal esophagus associated with food impaction and had fibrosis and thickening of the left cricopharyngeus and thyropharyngeus muscles. CONCLUSIONS: Iatrogenic damage to the caudal pharyngeal constrictor muscles, the intrinsic musculature of the upper esophagus, or their innervation, or damage to the peri-esophageal fascia or esophageal adventitia may cause upper esophageal incompetence in horses after LP.