Male Dogs are Less Fertile, and Researchers Believe it’s Happening to Us Next
A recent trend has been observed all over Britain where male dogs from 5 different breeds have been losing their fertility by up to 30 percent. It will be the case that they’ll no longer be able to reproduce, but there’s a chance that we humans could be next.
“Male dogs who share our homes are exposed to similar contaminants as we are. So, in a sense, the dog is a sentinel for human exposure,” said lead researcher Richard G. Lea, from the University of Nottingham
The work here started way back in 1988 when the team analysed 232 dogs from five different breeds. Labrador retrievers, Golden retrievers, Curly coat retrievers, Border collies and German shepherds were the five breeds here. The reasons these dogs were chosen is because they all lived in the same place and were exposed to the same conditions. Moreover, their health and lineage are well documented.
Over the course of 26 years, the researchers collected sperm samples from a group of dogs in between 42 and 97. The ones with the poorest sperm quality were removed from the group. But even with this removal, they noticed a drop in quality of about 2.4% each year. In total, some 30% decline has been observed thus far,
“Between 1994 and 2014, they also noticed that the mortality rate of the female puppies, although small, showed a threefold increase,” writes Jan Hoffman for the NY Times. “And the incidence of undescended testicles in male puppies, also small, had a 10-fold increase, to 1 percent from 0.1.”
The team isn’t sure what’s causing this, but they have a hunch. They pass the blame on PCBs. These chmicals were once widely used in paints and plastics, but have since fallen out of use since the 1970’s. Nevertheless, these chemicals have a big half-life and they are now found everywhere, including in dog food.
“The scientists cannot determine how the chemicals were introduced into the food supply; these are not additives,” says Hoffman. “But Lea and his colleagues speculate that they could be in the packaging as well as in water that came into contact with any ingredients.”
The correlation between the fertility of male dogs and us humans is pretty much the same. What’s affecting them, may be affecting us as well. There have been some studies made which have shown that the quality of human semen has also decreased over the years. By itself the data isn’t enough to make a definite connection between the two incidents, but it is possible that it’s there.
“If you think about it, we are exposed to a cocktail. Who knows how many chemicals are out there and what they are doing?” Lea said.
“What we have been able to do here is just to pull out ones that we know are present, and we have tested those in terms of their effects and it does suggest there is an impact. The next stage – and it is a big next stage – is trying to tease out what else is there and how those chemicals are interacting.”
The paper, titled has been published in Scientific Reports.