title: Semen evaluation and fertility assessment in a purebred dog breeding facility.
abstract: Semen quality in dogs has not been assessed in a longitudinal study that includes endpoints of female fertility and pregnancy. Although use of artificial insemination with chilled semen is increasingly used in canine reproduction, the resultant level of predictability and odds of fertile matings for dogs is still not fully understood. This research provides, for the first time, comprehensive semen evaluation in a large population of dogs in which fertility has been tracked. Duplicate ejaculates were obtained from 39 Labrador retriever males of the Guide Dogs for the Blind (San Rafael, CA, USA) breeding program. Sperm endpoints were determined in fresh semen and extended chilled semen at 48 hour after collection. Evaluation included total and progressive motility, average path velocity, morphology, membrane lipid peroxidation, presence of sperm reactive oxygen species, sperm chromatin structure, and mitochondrial DNA copy number. Male age ranged from 1 to 10 years and were grouped as young (Y; 1-3 years, n = 21), middle aged (M; 4-6 years, n = 13), and senior (S; 7 years or greater, n = 5) for analysis. The effects of age and sperm state (fresh vs. chilled) on the above sperm endpoints were determined using a linear mixed effects model. Semen endpoint values for all parameters were established for this group of fertile males. Progressive motility was only lower in the senior male chilled samples compared to all other groups, fresh and chilled (P < 0.05). Velocity decreased with increasing age and was lower overall in chilled samples (P < 0.05). Percent morphologically normal sperm was lower in senior dogs compared with the other age groups (P < 0.05). The presence of reactive oxygen species was lower in chilled samples compared with fresh (P < 0.05). For sperm chromatin structure, the senior-aged group had a higher %COMPαtthan the middle-aged group (P < 0.05). Bayesian analysis determined that no differences were seen in total motility, membrane lipid peroxidation, and mitochondrial DNA copy number, with regard to conception rate or average litter size between age groups or between fresh and chilled samples. We observed no effects from semen quality on fertility or fecundity regardless of age, despite the differences found in semen quality. The use of advanced laboratory tests to evaluate sperm parameters beyond the standard motility, morphology, and concentration will open investigation to more specific and sensitive fertility tests in canine reproduction.
authors.affiliation: Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, California, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Hesser
authors.affiliation: Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, University of California, Davis, California, USA.
authors.forename: Christa
authors.initials: C
authors.lastname: Darr
authors.affiliation: Guide Dogs for the Blind, California Campus, San Rafael, California, USA.
authors.forename: Kris
authors.initials: K
authors.lastname: Gonzales
authors.affiliation: Guide Dogs for the Blind, California Campus, San Rafael, California, USA.
authors.forename: Heather
authors.initials: H
authors.lastname: Power
authors.affiliation: Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, University of California, Davis, California, USA.
authors.forename: Tawny
authors.initials: T
authors.lastname: Scanlan
authors.affiliation: Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA.
authors.forename: James
authors.initials: J
authors.lastname: Thompson
authors.affiliation: Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Love
authors.affiliation: Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, California, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Christensen
authors.affiliation: Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, University of California, Davis, California, USA. Electronic address: smeyers@ucdavis.edu.
authors.forename: Stuart
authors.initials: S
authors.lastname: Meyers
mesh_terms: D000818:Animals; D004285:Dogs; D005260:Female; D005298:Fertility / Q000502:physiology*; D008297:Male; D011247:Pregnancy; D012661:Semen / Q000502:physiology*; D055101:Semen Analysis / Q000662:veterinary*
keywords: Canine sperm; Male fertility; Reproductive senescence