Equine Metabolic Syndrome: Endocrine Disruptors Under Scrutiny

According to new research, endocrine-disrupting chemicals present in the environment of horses play a role in the development of equine metabolic syndrome. Environmental pollution (dioxins, hydrocarbons, etc.) poses a growing threat to human and animal health. It has been linked to numerous diseases (asthma, diabetes, cancer, etc.) that affect humans as well as other mammals.

There is little research on the exposure of domestic animals to endocrine disruptors, which contaminate grazing areas in particular. This first study in horses shows that these chemicals may play a role in the development of equine metabolic syndrome, an endocrine disorder similar to diabetes in humans. This discovery, made by researchers at the University of Minnesota funded by the Morris Animal Foundation, could partially explain the variability in the severity of this metabolic disease in horses, beyond other predisposing factors such as overfeeding, lack of exercise, and the season (grazing laminitis in the spring and early summer).

Knowing that environmental toxins contribute to the onset of the disease will make it possible to seek ways to reduce horses’ exposure to these industrial compounds or pollutants. In this study, researchers analyzed plasma samples from more than 301 ponies and horses from 32 farms in the United States and Canada. They focused specifically on Welsh and Morgan horses, as these two breeds are more susceptible than others to equine metabolic syndrome. The team measured the concentrations of endocrine disruptors detected by the horses’ estrogen and aryl hydrocarbon (AhR) receptors. At the same time, they determined whether each horse’s blood test results were consistent with the metabolic profile of equine metabolic syndrome (measurement of insulin levels and blood glucose levels before and after the administration of a sugary feed). Analysis of the results revealed correlations between plasma concentrations of endocrine disruptors and these variables.

The study thus demonstrates that

Endocrine disruptors are present in equine plasma, and their accumulation explains certain environmental variations observed in horses with equine metabolic syndrome; however, the precise role and the dose-response relationship have not yet been determined. This is the first example of an association between endocrine disruptors and the phenotypic components of a clinical disease in domestic animals.

Chemicals that disrupt the endocrine system are generally man-made substances found in pesticides, plastics, and cosmetics. Ubiquitous in the environment, they can mimic or block natural hormones, leading to disruptions in hormonal physiology. For this reason, they are known to have harmful effects on humans and wildlife. Horses likely come into contact with these pollutants through grazing.

Equine metabolic syndrome, for which there is no effective treatment, is characterized by endocrine abnormalities in affected horses and ponies. Obesity—whether generalized or localized—is a characteristic sign, associated with insulin resistance. This syndrome is also one of the most common causes of laminitis. Although it is difficult to avoid environmental pollutants at present, the findings from this study will help veterinarians better assess the risks of disease onset and the possibilities for prevention.

The extent of the association between endocrine disruptors and equine metabolic syndrome remains to be studied. This will be the focus of future research, which should deepen our understanding of this disease, thereby contributing to advances in equine veterinary medicine in the field of insulin resistance.

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https://vetitude.fr/exposition-aux-parabenes-les-animaux-de-compagnie-ne-sont-pas-epargnes/

https://vetitude.fr/residus-de-medicaments-une-conference-internationale-et-un-plan-national-pour-lutter-contre-les-micropolluants/