Grazing Mares on Pasture with Sycamore Maples: A Potential Threat to Suckling Foals and Food Safety through Milk Contamination.

Benoît Renaud,David Stern,Thierry Petitjean,François Boemer,Pascal Gustin,Anne-Christine François,Dominique-Marie Votion,Caroline Kruse,Amandine Piot

doi:10.3390/ani11010087

Abstract

Simple SummaryEquine atypical myopathy is seasonal poisoning resulting from the ingestion of seeds and seedlings of the sycamore maple that contains toxins. Literature mentions several cases of intoxication among gravid mares and in unweaned foals. The objective of this study was to determine whether the toxins responsible for atypical myopathy could pass to the foal via suckling. Four mares that were pasturing with sycamore in the vicinity were milked. Analysis revealed the presence of toxins in milk. This unprecedented observation could partially explain cases of unweaned foals suffering from atypical myopathy. However, a transplacental transfer of the toxin cannot be excluded for newborn cases. Besides being a source of contamination for offspring, milk contamination by toxins from fruits of trees of the Sapindaceae family might constitute a potential risk for food safety regarding other species’ raw milk or dairy products.Equine atypical myopathy (AM) is seasonal intoxication resulting from the ingestion of seeds and seedlings of the sycamore maple (Acer pseudoplatanus) that contain toxins, among them, hypoglycin A (HGA). Literature mentions several cases of AM among gravid mares and in unweaned foals. The objective of this study was to determine whether HGA and/or its metabolite are present in milk from grazing mares exposed to sycamore maple trees as confirmed by detection of HGA and its metabolite in their blood. Four mare/foal couples were included in the study. Both HGA and its metabolite were detectable in all but one of the milk samples. To our knowledge, this is the first study describing transfer of HGA to the milk. This unprecedented observation could partially explain cases of unweaned foals suffering from AM. However, a transplacental transfer of the toxin cannot be excluded for newborn foals. Besides being a source of contamination for offspring, milk contamination by toxins from fruits of trees of the Sapindaceae family might constitute a potential risk for food safety regarding other species’ raw milk or dairy products.

Highlights

Atypical myopathy (AM) is a non-exercise-induced rhabdomyolysis syndrome that strikes grazing equids on a seasonal rhythm
The objective of this study was to determine whether hypoglycin A (HGA) or MCPA-carnitine are present in milk from mares exposed to sycamore maple trees
The foals were 1 to 5-months old, which implies that none of them was exclusively milk-fed at the time of sampling (Table 1)

Summary

Introduction

Atypical myopathy (AM) is a non-exercise-induced rhabdomyolysis syndrome that strikes grazing equids on a seasonal rhythm This condition has been initially described in the 1980s in the United Kingdom [1], but was later reported in about 15 European countries [2], in the US [3], and in New Zealand [4]. In 2019, a second toxin, methylenecyclopropylglycine (MCPG), has been described as playing a part in the ethiopathogenicity of AM [8]. This toxin is a structural analog of HGA, and is present in sycamore maple seeds [9]. MCPG has not been sought in seedlings but might be present

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