If any of your canine clients are considering breeding, you might want to advise them on dog food. At least, that’s what a new study suggests.

Researchers from The University of Nottingham in the United Kingdom found that sperm quality in a population of stud dogs studied over a 26-year period had fallen significantly. Additionally, a potential link to environmental contaminants was identified.

The study was published in Scientific Reports on Sept. 16.

The study centered on samples taken from stud dogs at an assistance dogs breeding center over the course of 26 years. Five breeds were studied, including the Labrador retriever, golden retriever, curly coat retriever, border collie, and German shepherd

Semen was collected from the dogs and analyzed to assess the percentage of sperm that showed a normal forward progressive pattern of motility and that appeared normal under a microscope (morphology).

Over the 26 years of the study, the researchers found a striking decrease in the percentage of normal motile sperm. From 1988-1998, sperm motility declined by 2.5% per year and following a short period when stud dogs of compromised fertility were retired from the study. Sperm motility from 2002-2014 continued to decline at a rate of 1.2% per year.

In addition, the researchers discovered that the male pups generated from the stud dogs with declining semen quality had an increased incidence of cryptorchidism, a condition in which the testes of pups fail to correctly descend into the scrotum.

Sperm collected from the same breeding population of dogs, and testes recovered from dogs undergoing routine castration, were found to contain environmental contaminants at concentrations able to disrupt sperm motility and viability when tested.

The same chemicals that disrupted sperm quality were also discovered in a range of commercially available dog foods, including brands specifically marketed for puppies.

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