Distal interstitial epididymitis in young rats

• Published in: Toxicologic pathology Vol. 43; no. 3; p. 449
• Main Authors: Hoffmann, Guenther, Belote, Duane A, Suttie, Andrew W, Buetow, Bernard S, Muhumuza, Luke
• Format: Journal Article
• Language: English
• Published: United States 01.04.2015
• Subjects: Animals; Animals, Laboratory; Autoimmune Diseases - pathology; Edema - pathology; Epididymis - pathology; Epididymitis - epidemiology; Epididymitis - pathology; Incidental Findings; Male; Organ Size; Rats; Rats, Sprague-Dawley; Sprague-Dawley; sporadic; epididymis; rat; interstitial; incidental; epididymitis
• ISSN: 1533-1601
• DOI: 10.1177/0192623314526320

A sporadic, diffuse, interstitial mixed cell epididymitis of unknown etiology was noted in the epididymal cauda and distal corpus of young control Sprague-Dawley (SD) rats. Rats from 2 different suppliers were examined as part of routine toxicology studies. The incidence of this finding was 5/5 (study 1), 2/7 (study 2), and 2/7 (study 3). Although 2 of these studies partially overlapped temporally, none of the affected animals from any study was maintained concurrently with affected animals from any of the other 2 studies, and infectious causes, control article toxicity, or autoimmune processes were considered unlikely etiologies. Inflammation similar to that noted in the epididymides of these young rats was not present in other tissues and was not noted in study cohorts sacrificed at ages older than approximately 11 weeks or in rats of similar age from other concurrent studies. Similar findings were noted sporadically in historical control data, and consequently an age-related finding of unknown etiology and occurring in sporadic clusters is reported in SD rats ≤11 weeks old.