Environmental chemicals impact dog semen quality in vitro and may be associated with a temporal decline in sperm motility and increased cryptorchidism

Abstract

Adverse temporal trends in human semen quality and cryptorchidism in infants have been associated with exposure to environmental chemicals (ECs) during development. Here we report that a population of breeding dogs exhibit a 26 year (1988–2014) decline in sperm quality and a concurrent increased incidence of cryptorchidism in male offspring (1995–2014). A decline in the number of males born relative to the number of females was also observed. ECs, including diethylhexyl phthalate (DEHP) and polychlorinated bisphenol 153 (PCB153), were detected in adult dog testes and commercial dog foods at concentrations reported to perturb reproductive function in other species. Testicular concentrations of DEHP and PCB153 perturbed sperm viability, motility and DNA integrity in vitro but did not affect LH stimulated testosterone secretion from adult testis explants. The direct effects of chemicals on sperm may therefore contribute to the decline in canine semen quality that parallels that reported in the human.

Dog sperm swimming parameters analysed by computer‐assisted semen analysis of motility reveal major breed differences

“…In conclusion, from the major differences observed between breeds in sperm kinematic traits, which confirm the diversity in other sperm traits already described, it may be advisable to refrain from a generalization for dogs when carrying out reproductive studies in this species (Hewitt, Leahy, Sheldon, & England, ; Peña, Barrio, Quintela, & Herradón, ; Sánchez‐Calabuig et al, ). On the other hand, dog breeds could constitute a very useful model to examine a diversity of responses in reproductive studies, including the effect of environmental contaminants on sperm traits (Lea et al, ) and also for understanding the different aspects of female reproductive biology that may influence the evolution of sperm traits, as carried out in other taxa focusing on intra‐ and interspecific comparisons (Anderson et al, ; Roldan et al, ; Soler, García et al, ).…”

“…On the other hand, dog breeds could constitute a very useful model to examine a diversity of responses in reproductive studies, including the effect of environmental contaminants on sperm traits (Lea et al, 2016) and also for understanding the different aspects of female reproductive biology that may influence the evolution of sperm traits, as carried out in other taxa focusing on intra-and interspecific | 801 VALVERDE Et AL.…”

Selection of Breeding Stock among Australian Purebred Dog Breeders, with Particular Emphasis on the Dam

“…Further understanding of breed priorities according to the brachycephalic index would allow targeted implementation of breed standards and criteria. While comparative data on conception and prevalence of caesarean sections is lacking across all dog breeds, a recent study highlighted a general reduction in the fertility of male dogs [35]. In a retrospective cohort study of Norwegian purebred dogs, 8% of pups died before eight days of age, in 10,810 litters and 224 breeds [36].…”

Canine cryptorchidism: An update

“…However, the functional role of UCN and its receptors in testicular descent and function needs to be investigated in future studies. In another recent report (Lea et al, 2016), it was postulated that environmental chemicals, including diethylhexyl phthalate (DEHP) and polychlorinated biphenyl 153 (PCB153), may increase the incidence of cryptorchidism. However, a direct correlation study between environmental chemicals and cryptorchidism is lacking.…”