August 01, 2022

Research has shown that an identifiable set of environmental factors can impact dog semen quality, sperm motility, and increased cryptorchidism in canine stud dogs.
In 2016, a study released by the University of Nottingham1 stated that their 26-year research project indicated that the fertility of dogs may have suffered a sharp decline with decreased sperm quality. Dr. Richard Lea, Reproductive Biology in the University’s School of Veterinary Medicine and Science, who led the research, said: “This is the first time that such a decline in male fertility is reported in the dog. We believe this is due to environmental contaminants, some of which we have detected in dog food and the sperm and testes of the animals themselves.”
The controlled canine study has also been correlated to a decline in human sperm count over the past three decades. “While further research is needed to demonstrate a link conclusively, 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 similarly to therapies.”
This study proved that an increased presence of diethylhexyl phthalate (DEHP) and polychlorinated biphenyl congener 153 (PCB153) are the primary chemicals responsible for the results in this research. These chemicals are found in typical dog food brands and everyday household and other pet-related products.

Figure 1. Temporal changes in semen quality in a population of stud dogs. Graphical summaries of the final statistical model parameters are shown for (a) Percentage Normal Motility, (b) Percentage Live Normal Sperm and (c) Total Sperm Output. In 1999 to 2001, dogs with poor semen quality were removed from the programme. Values of each parameter are give for years 1988-1998 and years 2002-2014 (n=232 dogs: 42 to 97 in any one year). Statistical analysis: conventional multilevel models (MLwin version 2.22) used to evaluate change in semen quality over time accounting for repeated seam measurements. Error bars represent ± the standard error of each estimated mean point value from the model.

What can you do to reduce your stud dog’s exposure to DEHP & PCB153? You should be aware of some potentially toxic environmental items, which might contain these chemicals, that your dog will regularly encounter:
  • Canned Dog Food: The lining inside dog food cans may contain BPA, known to cause changes in blood chemistry and the gut microbiome. In just two weeks, studies of dogs switching from kibble to canned food almost tripled their levels of BPA. BPA can cause cases of hyperthyroidism in older dogs, which affects sperm quality. Look for higher-end brands of canned food which do not use BPA for their inner can lining.
  • Dog Shampoo/Conditioner: If your shampoo or conditioner has preservatives and fragrance chemicals, there is a high likelihood that phthalates (as in DEHP) are present. Avoid these products and opt for “fragrance-free,” natural products.
  • Vinyl & Plastics: Whether it’s your dog’s toy or even your vinyl flooring, these products can increase overall levels of DEHP in your stud dog’s system, which will decrease sperm quality/motility. When choosing toys, opt for natural rope, cloth, or wool products. Consider making your toys out of old clothes–sweatshirts and jeans are excellent options and tougher to tear than t-shirts. If your dog prefers plastic chew toys, look for phthalate & BPA-free ones. Research has found some of the highest levels of phthalates in “bumper toys” like those used to train hunting, dock diving, and agility dogs.
  • Dog Beds: In 2016 they found foam beds are a concern to stud dogs because they have many flame retardants and PFCs. These can impact your dog’s health because of the amount of time spent sleeping in them. Beds can be quite an investment, but will cost less than veterinary bills in the long run. Of course, the least toxic options are produced from natural materials like cotton and wool.
  • Lawn Products: As you can imagine, lawn products contain herbicides and pesticides full of chemicals. An example is 2, 4-D–one of the main ingredients in widely used lawn products. You may not be able to control your pets’ exposure to all of these types of products, but you can make sure to wash/wipe their feet and legs when they come home, and avoid using these products on your lawn where your stud dog likely spends most of his time.

These are just some everyday items that could affect your dog’s overall health, as many are related to canine cancer studies and your stud dog’s sperm quality. The only way to know if the changes you are making to improve your dog’s environment are working is to regularly test your dog’s sperm count and the concentration of Progressive Motile Sperm Cells per mLin its ejaculate.  Good nutrition, exercise, and supplements can also increase a stud dog’s fertility. Products such as PetCount’s at-home sperm test kit can give you an accurate reading of improvements quickly and conveniently to help you measure and track any changes.

Figure 3. Concentrations of environmental chemicals in adult dog testes and commercially available dog food. (a,d,g) PCB congeners, (b,e,h) PBDE congeners and (c,f,i) DEHP were measured in (a-c) testes, (d-f) dry dog food and (g-1) canned dog food. Each circle represents a single testis or food sample. Blue circles show PCB 153 and DEHP that were detected above base levels in testes and food and selected for in vitro studies. Line indicates mean value.