Crotalaria spectabilis poisoning in horses

This was an interesting study where whole oats were contaminated with rattlebox seed causing poisoning of horses. Rattlebox seeds are a dark brown somewhat discoid shape so could be distinguished from oats by appearance. Edited from the North Carolina toxic plants site: Showy crotalaria, is an annual herbaceous plant that blooms from August to November. Although it is nonnative to the United States, it was introduced to the southeast United States from the tropics. It spans from Virginia south to Florida and west to Texas. It prefers open fields, wastelands, disturbed sites such as pastures and cultivated fields and roadsides with sandy soil and full exposure to the sun.

We have images of the plants and further information in the article. Below is an image of the seeds.
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Crotalaria spectabilis poisoning in horses fed contaminating oats
Toxicon. 2021 Apr 11;S0041-0101(21)00105-7.

Authors
Maira Dos Santos Carneiro Lacerda 1 , Tais Meziara Wilson 1 , Verônica Lourença de Souza Argenta 2 , Érika Garcia de Araújo Pinto 3 , Juliana Targino Silva Almeida E Macêdo 1 , Benito Soto-Blanco 4 , Kelly Moura Keller 4 , Pedro Miguel Ocampos Pedroso 1 , Antônio Carlos Lopes Câmara 5
Affiliations

1 Veterinary Pathology Laboratory, College of Agronomy and Veterinary Medicine, Universidade de Brasília, Via L4 Norte s/n, Asa Norte, Brasília, DF 70910-970, Brazil.
2 Large Animal Veterinary Teaching Hospital, College of Agronomy and Veterinary Medicine, Universidade de Brasília, Galpão 4, Granja do Torto, Brasília, DF 70636-200, Brazil.
3 Secretaria de Estado da Agricultura, Abastecimento e Desenvolvimento Rural do Distrito Federal, Brasília, DF 70770-914, Brazil.
4 Veterinary College, Universidade Federal de Minas Gerais, Avenida Presidente Antônio Carlos 6627, Belo Horizonte, MG 31275-013, Brazil.
5 Large Animal Veterinary Teaching Hospital, College of Agronomy and Veterinary Medicine, Universidade de Brasília, Galpão 4, Granja do Torto, Brasília, DF 70636-200, Brazil. Electronic address: aclcamara@yahoo.com.br.

Abstract

The present report describes the clinical and pathological changes induced by the consumption of oats contaminated with Crotalaria spectabilis seeds by horses. Eighty horses were exposed to oats containing 10 g/kg of C. spectabilis seeds with 0.46% pyrrolizidine alkaloids, and 21 horses died within a 6-month period. Clinical signs included jaundice, apathy, a hypotonic tongue, ataxia, hyporexia, weight loss, aimless wandering, violent behavior, and proprioceptive deficits. Pathological findings were predominant in the liver and included periportal bridging fibrosis, megalocytosis, centrilobular necrosis, and bile stasis. Other findings were Alzheimer’s type II astrocytes in the cortex, midbrain, basal nuclei, brainstem and pons; multifocal edema and hemorrhage in the lungs; and degeneration and necrosis of the tubular epithelium of kidneys. Horses are highly sensitive to pyrrolizidine alkaloid-containing plants, and the observed clinical and pathological findings are typical of this poisoning. The seeds were planted, and botanical identification of the adult plants confirmed the diagnosis of C. spectabilis poisoning.

Keywords: Crotalaria spectabilis, Liver failure; Hepatic encephalopathy; Poisoning.