Salivary syndrome in horses: identification of slaframine in red clover hay.

The research focuses on investigating an outbreak of salivary syndrome among horses in North Carolina, which was found to be caused by ingestion of toxic red clover hay contaminated by the fungus Rhizoctonia leguminicola. The fungus was found to be less common in the hay after 10 months of storage and the hay’s toxicity reduced significantly after this duration. The study also provides the first direct identification of slaframine, a mycotoxin, in the toxic red clover hay.

Investigation of the Outbreak

• Researchers were focused on exploring the main cause of an outbreak of salivary syndrome in horses which was traced back to the intake of toxic red clover hay.
• Rhizoctonia leguminicola, a fungus, was prominently found in the identified toxic hay.
• It was established that the presence of this fungus in the hay reduced over the course of 10 months and so did the toxicity or biological activity of the hay.

Experimental Results

• Tests were conducted on guinea pigs by feeding them the toxic hay, leading to excessive salivation, piloerection, respiratory distress, and more frequent defecation.
• Purified extracts of the toxic hay and pure slaframine resulted in the same symptoms or responses, thus confirming the presence of the mycotoxin in the hay.
• The toxic hay initially contained 50 to 100 ppm (50 to 100 microgram/g) of slaframine, which reduced to about 7 ppm after 10 months.

Identification of Slaframine

• Slaframine was identified in the purified extracts of toxic hay using gas-liquid chromatography-mass spectrometry.
• This process entailed the usage of slaframine and seven synthetic derivates of it for the presumptive chromatographic identification of this mycotoxin.
• This was the first instance of direct identification of slaframine in toxic red clover hay, suggesting it as a key element contributing to the outbreak.