Salvia reflexa-contaminated hay poisoning in cattle

Salvia reflexa is an annual forb that has recently (2021) been reported to contaminate hay and cause fatal hepatotoxicity in cattle. It is possible that prior poisoning cases may have gone unrecognized due to the lack of information on fatal hepatotoxicity caused by S. reflexa. Two cases are reported. Case 1 occurred in December 2001 in Montana, in which 30 cows died out of 105. Case 2 occurred in 2023 in Wyoming, in which 111 cows out of 155 died. Poisoned cows in both cases had elevated aspartate aminotransferase and alkaline phosphatase activities with microscopic severe acute centrilobular necrosis with hemorrhage. These lesions were similar to those described previously in clinical and experimental S. reflexa trials. Hepatotoxic diterpenes of S. reflexa, salviarin and rhyacophiline, were detected in hay samples in both cases and in rumen contents from animals in Case 2. Plant specimens of S. reflexa were collected from 2 herbaria, representing collections from 12 states, and screened for salviarin and rhyacophiline. The S. reflexa toxins were found in herbarium samples suggesting if S. reflexa is present, it is potentially toxic to cattle.