Effect of body weight, age and breeding history on canine sperm quality parameters measured by the Hamilton-Thorne analyser.

During the last decade, several computer assisted sperm analysis (CASA) systems have been validated for canine sperm quality assessment. Regarding the impressive possibilities of these systems, further research is required to determine which CASA measurements are of clinical importance in canine andrology. In the present study, the sperm quality parameters obtained by the Hamilton-Thorne Semen Analyser (Ceros 12.1; HTR) were correlated with the body weight and the age of the dogs. Moreover, the sperm quality parameters of dogs with a different breeding history were compared. The sperm-rich fraction was collected from 111 dogs of 50 different breeds, which were presented at our department. Immediately after collection, the concentration, the total sperm output (TSO) and 13 different sperm motility and velocity characteristics were measured by the HTR. The percentage of live spermatozoa and the spermatozoal morphology were examined on eosin/nigrosin stained smears. Based on their breeding history, the dogs were divided in three groups: 'fertile' (n = 60), 'subfertile' (n = 17) or 'not used for breeding' (n = 34). Significant (p < 0.05) correlations were established between the body weight of the dogs and the TSO (r = 0.245) and velocity curvilinear (VCL; r = -0.220), respectively. The age was negatively correlated with the percentage of normal spermatozoa (r = -0.203; p < 0.05). The correlations with all the other evaluated sperm parameters were low and not significant. Significant differences between the 'fertile' and the 'subfertile' group were found for all of the evaluated sperm quality parameters (except for BCF, LIN, STR and MEDIUM). In conclusion, dogs tend to produce ejaculates with a lower percentage of normal spermatozoa with increasing age and dogs with higher body weights produce ejaculates with a higher TSO and a lower VCL. Significantly poorer sperm characteristics were found for dogs with lower in vivo fertility results.