Cooling of canine semen contaminated with urine

Résumé

Contamination of canine semen with urine, caused by urination during ejaculation or semen flow into the urinary bladder, is a common problem of sperm collected by electroejaculation for cryopreservation. The effects of urine on sperm cryopreservation, however, are not fully understood. The present study determined the acceptable upper level of contamination with urine for canine semen preservation after 24-h cooling. Semen samples obtained from 10 dogs were incubated with Ringer’s solution and different urine concentrations (0, 3, 6, 13, 25 50% and 100%) at 37°C for 20 min. The samples were centrifuged and the decanted sperm resuspended and cooled to 5°C for up to 24 h in a milk-based semen extender. The quality of the contaminated semen samples only differed from that of the control treatment after exposure to urine concentrations above 13%. After cooling, only sperm incubated with urine solutions above 25% exhibited lower activity than those incubated in simple Ringer’s solution. In conclusion, canine semen resists contamination with up to 13% urine for 20 min, and the motility of samples contaminated with up to 25% recovers similarly to that of uncontaminated samples if cooled at 5°C for 24 h in a milk-based extender.