What Canine Testes Inform Us About Human Fertility

In the early 1900s, miners used caged birds to monitor flight safety and alert them if they were inhaling harmful gas while they could still act to save themselves. Today, researchers are studying dogs to learn about the chemicals men are exposed to at home, looking for warning signs that human health may be at risk.

New study examined dogs, rather than birds, for early signs of toxicity

“Our work focuses on dogs, who share our pet environment and are therefore exposed to the same household pollutants as their owners,” says Rebecca Sumner, PhD, lecturer in basic veterinary science in the Department of Veterinary Sciences and Medicine at the University of Nottingham in the UK. “Many of the diseases and cancers that affect dogs also affect humans, so if environmental pollutants are responsible for altered reproductive health in humans, it is likely so in dogs,” she says.

The resulting new research suggests that the environment in which men live can have an impact on their reproductive health. The study, led by Dr. Sumner and other University of Nottingham scientists, and published in Scientific Reports in April 2021, examined geographic locations and compared them to environmentally harmful chemicals in dog tests, some of which are known to have effects on reproductive health.

The dog’s reproductive system is similar to that of humans

As with men, a dog’s testicles, or testicles, are the sex organ that produces semen and testosterone. Sperm health is important for the fertilization of a female egg and for the conception and production of offspring.

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Sumner notes that semen quality degrades over time in both dogs and humans. “Since this decline in humans has been linked to environmental pollutants, it seemed likely that the dog was a sentinel species,” which means it could serve as a warning. “We have shown that contamination in dog testicles affects sperm function in humans and dogs alike.”

Chemicals around men can affect sperm quality and other health characteristics

The new research builds on previous research looking at environmental chemicals and sperm quality. “In the current study, we looked at dog tests from the UK, Denmark and Finland for a range of environmental chemicals as well as testicular pathologies,” says Sumner.

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Concentration of chemicals by geographic location

“The two main observations were that the levels of chemical contaminants in dog tests and the extent of the pathologies observed depend on where the dogs lived,” says Sumner, noting that the differences included higher concentrations of chemicals used in flame retardants in samples from Finland and Denmark compared to Great Britain. In contrast, a class of industrial chemicals known as polychlorinated biphenyls was higher in the UK than in Scandinavia. Still, dog tests from Finland showed fewer pathologies than any other region. “Although we cannot prove cause and effect,” says Sumner, “these geographic differences add to the weight of the evidence that our environment determines the contaminants we are exposed to.”

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“Other published data support our results and underscore the need to control the release of chemical pollutants into the environment,” she emphasizes. “We exist in a changing world and are seeing significant changes in a variety of health parameters associated with chemical exposure to the environment. “

Experts share concerns about pollutants and human health

“I hope this research attracts the attention of everyone who is concerned about their reproductive health,” says Shanna Swan, PhD, author of Countdown: How Our Modern World Is Threatening Sperm Counts, Male and Female Reproductive Development, and Usage The future of the world endangers Human Race, who was not involved in the new research.

Sumner says she wants the data to create greater awareness of the pollutants we are exposed to on a daily basis and how we need to think about contamination in relation to human health, even when it is difficult to pinpoint all of the variables in action. “Unfortunately, we are exposed to a large number of chemicals in the environment that are broken down in the body and can even interact with one another,” says Sumner.

Flame retardants, chemicals made from plastic, are common in many households

The Sumner team chose flame retardants and chemicals made from plastic because they are ubiquitous in the environment and affect reproduction in a variety of different studies.

What about chemicals that can affect female fertility?

It is hoped that research in this area will continue to examine women’s reproductive health as well. “There are several plans to continue this research and a need too,” she says. “Our current PhD students are focused on advancing this area from both a female and a female perspective [animals with] herbivorous diets. Working on different types, such as B. sheep, suggest that exposure to pollutants may affect the ovary. We have a lot to do in this area that is relevant to human, dog and mammalian reproductive health. “

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In the meantime, says Dr. Swan, this result is “one of many scientific findings that should serve as a wake-up call for the severe decline in the reproductive health of many species on this planet”.