In a study conducted by the University of Minnesota, funded by the Morris Animal Foundation, researchers discovered a possible link between environmental factors and horses developing equine metabolic syndrome (EMS). The main factor they discovered was endocrine-disrupting chemicals (EDC).
EDCs are usually man-made substances that find their way into the environment, including pesticides, plastics and personal care products. They can mimic hormones in the body, blocking the real ones from properly carrying out their jobs. This can create harmful effects in not only horses but humans too. It is believed horses come into contact with EDCs through their food.
EMS has no cure and is characterized by endocrine abnormalities in horses and ponies. Physical signs typically include the development of fatty pockets or obesity. These animals also have altered insulin dynamics. EMS is a leading precursor to laminitis.
The discovery of this new factor is helping researchers understand the puzzle of why some horses developed EMS despite diligent care provided by owners.
“This is a pivotal piece of a very complicated jigsaw puzzle,” says Dr. Molly McCue, professor and interim associate dean of research in the College of Veterinary Medicine at the University of Minnesota. “It’s important that we be aware that these chemicals contribute to the problem, so we can look for a way to reduce horses’ exposure to them.”
The study was conducted on more than 300 horses from 32 farms in the United States and Canada. The focus was on Welsh ponies and Morgan horses due to their higher likelihood of developing EMS compared with other breeds. Data were collected on the horses’ lifestyles, which included information about their diet, exercise and past illness. Most importantly, researchers collected data on the horses’ farm location.
Plasma from the horses was collected and examined for EDCs that affect receptors in the horse pertaining to estrogen production and gene transcription. Blood tests were also conducted to see whether the results matched an EMS profile. Researchers conducted insulin and glucose tests at rest and a sugar challenge as well. Researchers then analyzed the results to look for correlations between plasma EDC concentrations and these variables.
The presence of EDC was likely to provide an environmental variance, but researchers concluded that the exact role and dose response to EDCs in horses with EMS is not clear at this time.
“The more we know about a disease, especially a devastating and incurable disease like EMS, the more we can find innovative ways to prevent it,” says Dr. Kelly Diehl, Morris Animal Foundation interim vice president of scientific programs. “While EDCs are difficult to avoid at the moment, the information from this study will greatly improve veterinarians’ ability to predict the disease and provide opportunities to prevent it.”
This is only the first study conducted on the relationship between EMS and EDCs, so the significance of the findings is yet to be determined. However, McCue hopes “future studies will further scientific understanding and help advance veterinary care for horses.”
The Morris Animal Foundation was founded in 1948 by veterinarian Mark L. Morris Sr. Its mission remains to bridge science and resources to advance the health of animals.
