Epididymal sperm granuloma and antisperm antibodies in donkeys

Abstract This study aimed to describe and compare semen parameters (pre-freeze and post-freezing) and antisperm antibodies of donkeys with epididymal sperm granuloma and healthy controls. Feral donkeys (n = 10) castrated in a concurrent study were enrolled in the present experiment. Three feral donkeys had unilateral granulomas, two feral donkeys had bilateral granulomas, whereas the remaining five were grossly normal. The granulomas were either single or multiple, firm, well-circumscribed, tan to red, and 1 to 5 mm in size. Upon incision, abundant, thick, tan to white-yellow fluid was recovered. Histopathology revealed epithelioid macrophages, multinucleated giant cells, and abundant sperm cell fragments with mineralized cellular debris. Each epididymis was dissected, and semen harvested for cryopreservation. Semen was assessed for sperm motility parameters, plasma membrane integrity, and mitochondrial membrane potential. All donkeys had semen cryopreserved in a standard manner. In addition, post-thaw semen from all donkeys was assessed for antisperm antibodies (IgG and IgA), acrosome integrity and morphology. After freezing, the progressive motility and percentage of sperm with an intact membrane of donkeys with sperm granuloma was lower (P = 0.04). There was no difference in total motility, morphology, damaged acrosome across groups (P > 0.05). Three donkeys with sperm granuloma (60%) displayed increased IgG and IgA antisperm antibodies. In conclusion, sperm granulomas only marginally affected sperm quality and resulted in IgG antisperm antibodies binding to sperm with damaged plasma membrane. It remains to be determined if sperm granuloma and antisperm antibodies affect fertility in donkeys.