Unilateral testicular degeneration in dogs: Effects on spermatozoal characteristics, testis and cauda epididymis

Abstract

Testicular degeneration is an important cause of poor fertility in dogs, but there is little knowledge on its effects on spermatozoa in affected dogs. The study investigated the specific effects of unilateral testicular degeneration (UTD) on spermatozoal characteristics in the testis and epididymis. Ten sexually mature Nigerian indigenous breed of dogs, comprising 5 normal dogs and 5 dogs with UTD were used for the study. The testis and epididymis were removed via orchidectomy for morphological and histopathological evaluation. Sperm in the testis and cauda epididymis were analysed. The samples were grouped into four as N1 (normal right testis), N2 (normal left testis), ND (non-degenerated testis in UTD dogs), and D (degenerated testis in UTD dogs). Data were analysed using one-way ANOVA. There were significant decreases (p<0.001) in testes weight, length, width and volume, and the gonado-somatic index in the D testes compared to the contralateral ND and the N groups. The D group also had significantly lowered epididymal sperm total and progressive motility, viability and concentration (p<0.001), and a decreased testicular sperm  concentration (p<0.01). Moreover, there was a decreased percentage (p<0.001) of morphologically normal sperm, with increased prevalence of  sperm abnormalities in the D group compared to the other groups. In comparison with the N groups, the ND group had a significantly lowered (p<0.05) epididymal sperm progressive motility, with increased percentage (p<0.01) of sperm with proximal cytoplasmic droplets and looped tails. The findings demonstrated that UTD in dogs adversely affected spermatozoa in the testis and cauda epididymis. There was also evidence of compromised spermatozoa in the epididymis contralateral to the degenerated testis. Keywords: Canine; Epididymis; Spermatozoa; Testicular atrophy; Testicular degeneration