Associations between canine male reproductive parameters and serum Vitamin D and prolactin concentrations

ASSOCIATIONS BETWEEN CANINE MALE REPRODUCTIVE PARAMETERS AND SERUM VITAMIN D AND PROLACTIN CONCENTRATIONS Adria Julianne Kukk Advisor: University of Guelph, 2011 Professor C.J. Gartley Maintaining reproductive health and diagnosing and treating conditions of infertility in stud dogs is important in canine theriogenology. However, there is still a great deal to be learned about reproductive physiology and factors that affect reproductive organs and semen quality in dogs. This thesis is an investigation of two factors in the male dog; serum 25-hydroxy Vitamin D (25OHVD) and prolactin (PRL) concentrations, and their possible associations with benign prostatic hyperplasia (BPH), prostate volume and/or sperm morphology and motility characteristics. 28 (Vitamin D Study) and 29 (28 plus one for the Prolactin study) client dogs of various breeds from the Ontario Veterinary College and Graham Animal Hospital in Southwestern Ontario, Canada were enrolled in the study from March to December 2009. Of these dogs 22 were successfully collected for semen. BPH was diagnosed using prostate volume measured by ultrasound, as well as clinical signs including blood in the ejaculate. Semen analysis was performed using manual microscopic techniques for morphology and computer assisted sperm analysis equipment for motility. In the vitamin D study, no associations were found between BPH and serum 25OHVD concentrations. In contrast, several sperm motility (motility, progressive motility, beat cross frequency (BCF), distance average path (DAP), curvilinear distance (DCL), linear distance (DSL), average path velocity (VAP), curvilinear velocity (VCL) and straight line velocity (VSL), amplitude lateral head displacement (ALH) and average orientation change (AOC)) and morphology characteristics (percentage normal sperm, head defects and detached heads) had desirable outcomes with 25OHVD concentrations between 120-180 nmol/l. Using bivariable analysis, positive associations were observed with 25OHVD and some semen quality characteristics from 4 to 8 years of age (motility, progressive motility, BCF, DCL, VCL, ALH, AOC) and at transformed prostate volumes smaller than or equal to 4.5 (motility, progressive motility, DCL, VCL, and normal morphology) while negative associations of these semen parameters were found at ages greater than 8 years and transformed prostate volumes greater than or equal to 5.5. Head defects were negatively associated with 25OHVD. Vitamin D may have an impact on spermatogenesis and normal sperm physiology that warrants further research. The prolactin study showed no statistically significant associations between serum PRL and BPH and serum PRL and sperm motility characteristics. However, two sperm morphology characteristics (percentage proximal droplets and percentage midpiece defects) had significant negative associations with PRL concentrations. Age interaction with PRL was also a factor in the percentage of midpiece defects with desirable outcomes associated at 4 years of age compared with older ages. Overall, undesirable outcomes occurred at PRL concentrations less than 2.5 ng/ml. In conclusion, both 25OHVD and PRL may have important roles in spermatogenesis and normal sperm physiology in the dog.