Related Experiment Video
Updated: May 1, 2026
08:30
Mouse Models of Epididymitis Induced by Pathogen-Associated Molecular Patterns
Published on: December 12, 2025
455
Distal interstitial epididymitis in young rats
Guenther Hoffmann1, Duane A Belote2, Andrew W Suttie2
1Covance Laboratories, Inc., Madison, Wisconsin, USA guenther.hoffmann@covance.com.
Toxicologic Pathology
|April 3, 2014
Summary
A rare inflammatory condition, epididymitis, was observed in young Sprague-Dawley (SD) rats. This finding, occurring sporadically in clusters, appears age-related and its cause remains unknown.
Area of Science:
- Veterinary Pathology
- Toxicology
- Rodent Models
Background:
- Routine toxicology studies utilize Sprague-Dawley (SD) rats.
- Epididymitis is an inflammation of the epididymis, a coiled tube that stores and carries sperm.
Purpose of the Study:
- To report a sporadic, idiopathic inflammatory finding in young control SD rats.
- To characterize the incidence and potential causes of epididymitis in this model.
Main Methods:
- Histopathological examination of epididymides from control SD rats in multiple toxicology studies.
- Evaluation of incidence across different studies and suppliers.
- Assessment of potential infectious, toxicological, or autoimmune etiologies.
Main Results:
- A diffuse, interstitial mixed cell epididymitis was observed in the cauda and distal corpus of young SD rats (≤11 weeks old).
- Incidence varied across studies (5/5, 2/7, 2/7).
- No concurrent housing of affected animals between studies, and infectious, control article toxicity, or autoimmune causes were deemed unlikely.
Conclusions:
- The observed epididymitis is an age-related finding in young SD rats (≤11 weeks old).
- The etiology remains unknown, presenting as sporadic clusters.
- This finding is specific to the epididymis and not observed in other tissues or older rats.
