Possible link between diet and declining fertility in dogs

Researchers at The University of Nottingham have shown a rapid decline in male dog fertility, with a potential link to environmental contaminants — including dog food.

The research, published in the academic journal Scientific Reports, found that sperm quality in a population of stud dogs studied over a 26-year period had fallen significantly.

The work highlighted a potential link to environmental contaminants after the researchers demonstrated that chemicals found in the sperm and testes of adult dogs — and in some commercially available pet foods — had a detrimental effect on sperm function at the concentrations detected.

The authors believe that the results may offer a new piece of the puzzle over the reported significant decline in human semen quality — a controversial subject which scientists continue to debate.

Dr Richard Lea, who led the research, said: “While further research is needed to conclusively demonstrate a link, the dog may indeed be a sentinel for humans. It shares the same environment, exhibits the same range of diseases — many with the same frequency — and responds in a similar way to therapies.”

The study centred on samples taken from stud dogs at an assistance dogs breeding centre over the course of 26 years and focused on five specific breeds of dogs — Labrador Retriever, Golden Retriever, Curly Coated Retriever, Border Collie and German Shepherd — with between 42 and 97 dogs studied every year.

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

Between 1988 and 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 to 2014 continued to decline at a rate of 1.2% per year.

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.