History:This mare presented with unilateral maxillary swelling. On exam, feed packing was noted in the deciduous premolar #606. Further evaluation of the swelling via diagnostic imaging revealed an impacted and abnormally oriented maturing second premolar #206 associated with a multilocular cystic structure.
Gross Lesions:The maxillary width is expanded twice normal by an impacted and malformed tooth #206 and an associated multilocular cystic structure (not identifiable on submitted slide). Tooth #206 is approximately half the normal length, crescentic, angled approximately 45 degrees off the eruption axis, and oriented apical-palatine to occlusal-buccal with the developing pulp horns forming nonparallel structures that wrap back apical-buccal. The multilocular cystic structure around tooth #206 measures up to 3x3x1cm, unilaterally expands the maxilla, and has an empty lumen with a smooth tan surface. Tooth #606, while in the process of physiologic exfoliation, also has a loss of the infundibulum with replacement by brown-green foreign material (feed packing).