Large-scale study of blood markers in equine atypical myopathy reveals subclinical poisoning and advances in diagnostic and prognostic criteria.

Equine atypical myopathy (AM) is a severe rhabdomyolysis syndrome primarily caused by hypoglycin A (HGA) and methylenecyclopropylglycine protoxins. This study aimed to refine diagnostic and prognostic criteria for AM while exploring apparently healthy cograzers. Blood samples from 263 horses, including AM cases (n= 95), cograzers (n= 73), colic horses (n= 19), and controls (n= 76), were analyzed for HGA, its toxic metabolite, and acylcarnitines profile. Diseased horses exhibited alterations in acylcarnitines that strongly distinguished them from controls and colic horses. Regression analyses identified distinct acylcarnitines profiles among groups, with cograzers showing intermediate alterations. Age and gelding status emerged as protective factors against AM. Furthermore, serum acylcarnitines profiling was valuable in predicting AM survival, with isovaleryl-/2-methylbutyrylcarnitine (i.e., C5 acylcarnitine) showing promise as both a diagnostic and prognostic marker. Subclinical alterations in cograzers underscore a novel aspect: the presence of subclinical cases of AM.