A new study has found that dog fertility has suffered a sharp decline in the past three decades, likely due to environmental or food contaminants.
Dogs are man's best friend and for millennia, humanity has intertwined with their existence. We've changed how dogs feed, their behavior, we've created countless breeds based on our needs and desires - perhaps to the point where our actions could be considered inconsiderate or even reckless, but that's beyond the point. This new study found that man-made contaminants are affecting dogs in a new, more subtle way: by damaging their sperm.
The study analyzed five dog breeds: labrador retriever, golden retriever, curly coat retriever, border collie and German shepherd. They collected semen from 42-97 dogs every year for the past 27 years, finding a significant decrease in quality.
Dr Richard Lea from the University of Nottingham led the study. He said:
"This is the first time that such a decline in male fertility has been reported in the dog and we believe this is due to environmental contaminants, some of which we have detected in dog food and in the sperm and testes of the animals themselves."
This might not seem like such a big deal, but as 'man's best friend,' dogs' and humans' fate seems tightly connected. Basically, we share the same environment as well as a number of physical characteristics, so whatever is affecting them may actually affect us. In fact, there is quite a stirred discussion regarding the quality of human sperm in recent years, with a number of medical experts claiming a decline.
"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."
Regarding human sperm, we still don't know for sure how "good" it is. There is a trove of scientific data indicating a decline in the past 70 years, but many have criticized the variability of data, due to the improvements in the available technology and laboratory personnel training.
The data in the dog study is more valuable in this sense, because it was gathered at the same lab, with the same technology and with similar techniques. It seems to support the idea of a decline in human sperm quality. Dr Lea added:
"The Nottingham study presents a unique set of reliable data from a controlled population which is free from these factors. This raises the tantalising 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."
Journal Reference: Environmental Chemicals Impact Semen Quality in Dogs in Vitro and May be Associated with a Temporal Decline in Quality and Increased Cryptorchidis.