Detection of maple toxins in mare’s milk

I have not seen a report of a foal illness from ingesting contaminated mare’s milk from maple ingestion. I presume that they are referring to the sycamore maple, a maple species with broad leaves somewhat resembling that of a sycamore tree. For more on this cause of myopathy see the article associated with this topic.
DrO

Detection of maple toxins in mare’s milk
J Vet Intern Med. 2020 Dec 18. doi: 10.1111/jvim.16004.
Authors
Johannes Sander 1 2 , Michael Terhardt 1 , Nils Janzen 1 3
Affiliations

1 Screening-Labor Hannover, Ronnenberg, Germany.
2 Department of Hygiene, Hanover Medical School, Hannover, Germany.
3 Department of Clinical Chemistry, Hanover Medical School, Hannover, Germany.

Abstract

Background: Plants from the Sapindaceae family that are consumed by horses (maple) and humans (ackee and litchi) are known to contain the toxins hypoglycin A and methylenecyclopropylglycine which cause seasonally occurring myopathy in horses and entero-encephalopathic sickness in humans. Vertical transmission of these toxins from a mare to her foal has been described once. However the mare’s milk was not available for analysis in this case. We investigated mare’s milk in a similar case.

Objective: We hypothesized that hypoglycin A and methylenecyclopropylglycine, like other amino acids’ are secreted into the milk.

Animals: Mare with atypical myopathy.

Methods: A sample of the mare’s milk and 6 commercial horse milk samples were extracted with a methanolic standard solution and analyzed for hypoglycin A, methylenecyclopropylglycine, and metabolites using tandem mass spectrometry after column chromatographic separation.

Results: There were hypoglycin A (0.4 μg/L) and the associated metabolites methylenecyclopropylacetyl glycine and carnitine (18.5 and 24.6 μg/L) plus increased concentrations of several acylcarnitines in the milk. The milk also contained methylenecyclopropylformyl glycine and carnitine (0.8 and 60 μg/L). The latter substances were also detected in 1 of 6 commercial horse milk samples.

Conclusions and clinical importance: Transmission of the maple toxins can occur through mare’s milk. Vertical transmission of Sapindacea toxins might also have importance for human medicine, for example, after consumption of ackee or litchi.