Fatal Ricin Toxicosis in a Puppy Confirmed by Liquid Chromatography/Mass Spectrometry when Using Ricinine as a Marker

Abstract

Ricin, a lectin from the castor bean plant (Ricinis communis), is considered one of the most potent plant toxins. Ingestion of masticated seeds results in high morbidity, with vomiting and watery to hemorrhagic diarrhea. The prognosis varies with the number of seeds ingested, the degree of mastication, individual susceptibility, and the delay in treatment. Low mortality restricts assessment of histologic lesions, and the literature on toxicologic analysis for ricin is limited. This report describes a fatal case of castor bean ingestion in a 12-week-old Mastiff puppy, with confirmation of ricin exposure through detection of the biomarker ricinine by liquid chromatography/mass spectrometry (LC/MS). Despite supportive therapy, the puppy died several hours after presentation for acute vomiting, diarrhea, and lethargy. At necropsy, a segment of jejunum and mesenteric lymph nodes were congested. When the owner reported the presence of castor beans in the dog's feces, selected formalin-fixed and unfixed tissues were submitted for diagnostic evaluation. Histopathologic findings included superficial necrotizing enteritis of the jejunum and occasional, random foci of coagulative necrosis in the liver. The alkaloid ricinine was detected in gastric content by using a newly developed LC/MS method. This confirmation of exposure is important in the diagnosis of ricin toxicosis, because ingestion of castor beans is not always fatal, histologic lesions are nonspecific, and the degree of mastication can influence the effective dose of ricin.