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Background: In small animal reproduction only few diagnostic tests are available which are defined as gold standards. Gold standards are methods having established accuracy for determining a test result that provides a standard to which another test can be compared to. The deficiency of these gold standards is based on the fact that only few studies investigating the quality of diagnostic methods have been conducted so far in some fields of veterinary medicine. Among other parameters, motility is routinely evaluated for canine semen analysis and the one most commonly used by practitioners. Freezing and thawing of canine semen compromise sperm cell motility. Motility is basically evaluated immediately after thawing and represents one of the first steps of a spermiogramme.
Objective: Standard operation procedures, however, have never been established for this test. Therefore, the objective was to examine the time dependent development of motility after thawing cryopreserved canine semen.
Methods: Semen of 35 clinically healthy dogs was collected and analysed. Conventional semen parameters, i.e. volume, concentration, motility, morphology and viability were evaluated individually in fresh semen and after cryopreservation. For cryopreservation CaniPRO™ Freeze A&B was used. Semen was thawed and diluted using CaniPRO™ Culture Medium. After thawing, semen was evaluated as before. In addition, every sample was tested for percentage of progressive motile, local motile and immotile sperm cells 0, 5, 20 and 60 minutes after thawing.
Results: Our findings show a significant difference between the percentages of motile sperm cells immediately after thawing compared to those five minutes after thawing. In frozen-thawed semen, positive correlations were found between membrane integrity and progressive motility: r = 0.79 (T0); r = 0.88 (T5); r = 0.69 (T20) and r = 0.65 (T60) (P < 0.05) Correlations between HOS test and progressive motility were: r = 0.64 (T0); r = 0.67 (T5); r = 0.57 (T20) and r = 0.57 (T60) (P < 0.05) in frozen-thawed semen.
Conclusions: To obtain comparable results it is required to develop standard operation procedures (Karger et al.2014). Based on our results, we suggest evaluating the percentage of progressive motile sperm cells of cryopreserved canine semen five minutes after thawing. The presented study underlines the necessity for critically scrutinizing generally accepted diagnostic tests. This is an essential prerequisite to warrant international comparability of information about semen quality. In times of emerging Evidence-based Veterinary Medicine, further research analysing the accuracy of diagnostic tests to standardize implementations is inevitable.