Variables affecting semen quality and its relation to fertility in the dog: A retrospective study

Although semen analysis is routinely used to evaluate the male reproductive potential in the canine species, only a few authors have attempted to relate semen characteristics to donor traits, such as age or weight, and fertility. This study evaluated the effects of dogs' age (young: 0–24 months, adult: 25–84 months, old: >84 months), size (small: 40 kg) and reason for semen collection (evaluation, artificial insemination, cryopreservation or research purposes) on the seminal characteristics and related the main seminal characteristics with fresh AI results. Overall, 251 semen examinations were performed from 140 dogs presented between 2000 and 2015 at the University of Pisa Veterinary Teaching Hospital. Conventional semen parameters (semen volume, sperm concentration and total number, subjective motility and sperm morphology) were evaluated. Overall, 227 (90.4%) samples contained spermatozoa. Azoospermic samples resulted from complete (n = 13, 9 dogs), or incomplete ejaculations (n = 11, 8 dogs), based on seminal alkaline phosphatase concentration and/or ancillary examinations. Reason for semen collection had a significant effect on semen volume, sperm total number and sperm concentration. The proportion of normal spermatozoa was lower in dogs presented for semen evaluation (P