First Report of Parascaris equorum in a White-Tailed Deer, Odocoileus virginianus, from Mansfield, Pennsylvania, U.S.A.

Abstract A gravid adult female nematode recovered from the rumen of a white-tailed deer, Odocoileus virginianus, was identified as Parascaris equorum, a common and cosmopolitan ascaridoid nematode parasite of horses and other equids. The cervine host was a 2-yr-old female that was presented to the Large Animal Soft Tissue Surgery service of the Cornell University Hospital for Animals (Ithaca, New York), with a 3-mo history of right-sided, unilateral, mucopurulent nasal discharge and weight loss. The doe was placed under general anesthesia, and radiographs of the head and thorax were taken. Rhinoscopy of both nasal passages was performed, during which time the rumen became distended, necessitating deflation. An orogastric tube was placed in the rumen and gas was successfully removed. Upon withdrawal of the tube, a 22.9-cm pinkish white ascarid worm was recovered from its lumen. Closer examination of the specimen revealed 3 large prominent ascarid-type lips consistent with P. equorum. The location of the vulva was 5.7 cm from the anterior end. Eggs recovered from the uterus were morphologically identical to Parascaris eggs. Ten eggs were measured, and the average measurement was 86 × 87.3 µm (with a SD of 3.2 and 2.8 µm for height and width, respectively). Lastly, the esophagus was dissected and examined, and no ventriculus was observed. The identification of the recovered nematode as P. equorum seems to be the first record of this parasite from the white-tailed deer.