Male dogs have been steadily losing their ability to reproduce since the 1980s, according to a study published this week by the University of Nottingham.
The study, which examined between 42 to 97 dogs a year from 1988 to 2014, found that male canines saw an annual decline in quality semen.
While more research is needed on the subject, university researchers said they are concerned that environmental factors causing dogs to lose their fertility could also apply to humans.
“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," Richard Lea, professor at the University of Nottingham, said.
Five breed types were used for research: Labrador retriever, golden retriever, curly coat retriever, border collie and German shepherd.
The study found that from 1988 to 1998, sperm mobility declined 2.5 percent annually. From 2002 to 2014, the decline continued at 1.2 percent per year.
The study reported that dogs were exposed to a number of environmental contaminants which affected the sperm motility and viability. Many of those contaminants were found in commercially available dog foods.
“The Nottingham study presents a unique set of reliable data from a controlled population which is free from these factors," Lea said. "This raises the tantalizing prospect that the decline in canine semen quality has an environmental cause and begs the question whether a similar effect could also be observed in human male fertility.”