Evaluation of short-term storage of canine semen at room temperature and at 37°C – Preliminary study

Keeping dog raw semen at room temperature would prove convenient for practitioners, but validated information regarding short-term storage of semen is scarce. 0.4 ml of sperm rich fraction from 10 healthy beagles (age 1 to 7 years) were collected by digital manipulation, pooled and divided into 3 groups: (1) dilution 1:3 with homemade Tris-fructose 20% egg yolk, (2) dilution 1:3 with a commercial egg yolk-based extender (CaniXCell®) and (3) a sample left undiluted. One half of samples was stored at room-temperature (RT, 22°C) in the dark and the other half in the incubator at 37°C. Samples were submitted to microscopy and CASA (IVOS IITM), at 6 time points post-collection: 0, 12, 18, 24, 36 and 48h. Progressive Motility (PM) was assessed at all times and percentage of wobble movements was evaluated, as a marker of hyperactivation, if PM was higher than 30%. The initial PM at T0 averaged 85%. PM dramatically dropped below 6% in all groups at 37°C and further evaluation was discontinued. At RT, PM was still higher than 70% and 50% at 12 and 24 hours respectively in all groups. Surprisingly, non-diluted semen still showed 18% of MM after 48h, while it was nil in both diluted groups. Percentage of wobble movements was significantly lower at 24h in non-diluted semen than in diluted groups. The premature hyperactivation of diluted semen probably explains the shorter survival time in these samples. No bacterial contamination was observed under microscopy throughout the experiment. These results suggest that short-term storage of good quality undiluted semen at room temperature in the dark may be adequate to inseminate a bitch within 12 hours.