The effect of extensive chorioptic mange of the scrotum on reproductive function of the ram.

Reproductive function was assessed in 14 stud rams which had been rejected as genitally unsound because of extensive chorioptic mange (Chorioptes bovis) of the scrotum. Severe seminal degeneration was observed in all of these rams. Mean testicular weight of the affected rams was 72.2 +/- 18.4 (S.D.) g, while that of the non-affected control rams was 190.1 +/- 38.2g. The seminiferous tubules of the atrophic testes were severely shrunken and spermatogenic arrest occurred at the spermatogonia or primary spermatocyte stage. Androgenic status and libido as assessed by seminal fructose, seminal vesicle weight, seminal fructose and reaction time were not affected by the disease. The average testicular temperature of 11 rams with extensive scrotal mange and severe testicular atrophy was 0.6 degrees C to 3.1 degrees C (average 1.7 degrees C) higher than that recorded from 11 control rams. The exudative dermatitis did not penetrate the tunica vaginalis sac and had no apparent effect on the general health of the rams. It was concluded that scrotal mange causes testicular degeneration by raising the temperature of the scrotal contents. Four rams that had severe testicular atrophy with complete spermatogenic arrest showed an acceptable level of semen production following treatment of their mange lesions. Recovery of spermatozoal production was also observed following spontaneous cure of chorioptic mange lesions in a ram whose scrotum had become severely thickened and pendulous due to long-standing chrorioptic mange.