Suspected poisoning in beef cattle from ingestion of Prosopis nigra pods in north-western Argentina

Highlights

• First report providing local information on outbreaks of poisoning by P. nigra pods in cattle.

• The macroscopic and microscopic findings were consistent with those observed in poisoning by other Prosopis species.

• P. nigra has wide geographical distribution in the Argentina, Paraguay, Brazil and Uruguay region.

Abstract

The aim of this paper was to present the first report of Prosopis nigra poisoning of cattle in Argentina. Outbreaks occurred in five farms located in Salta and Santiago del Estero provinces. All animals were examined, euthanized and necropsied. Clinical signs included tongue protrusion, twitches and tremors of muscles of mastication, weight loss and lethargy. Severe atrophy of the masseter, buccinator and lingual muscles was observed, along with neuronal vacuolation in the nuclei of the trigeminal, facial, and hypoglossus nerves. These findings and the clinical signs are consistent with results obtained in animals, spontaneously and experimentally intoxicated with Prosopis juliflora in previous studies. Several species of this genus are native to Argentina. Farmers should be warned about the suspected toxicity by Prosopis nigra, since this species has wide geographical distribution in the country.

Introduction

The genus Prosopis, family Leguminosae (Fabaceae), subfamily Mimosoideae, is native to the Americas, Africa and Asia, and comprises a great number of species (Pasiecznick et al., 2001). In Argentina, the species of this genus are known as “Algarrobos” (Verga et al., 2009). Its pods are a source of animal feed in many regions of the world due to their nutritional value (Silva, 1981; Silva et al., 1990; Riet-Correa et al., 2012). Despite this, spontaneous cases of intoxication have been observed in animals that remain in areas occupied by “algarrobos” for more than a year or longer than a fruiting period (Lima et al., 2004; Assis et al., 2009).

To date, all reports of toxicity by the genus Prosopis in animals have been associated with consumption of P. juliflora pods (Lima et al., 2004; Tabosa et al., 2004; Silva et al., 2006; Assis et al., 2009; Câmara et al., 2009). Spontaneous intoxication by P. glandulosa in goats was also reported (Washburn et al., 2002). Moreover, a spontaneous poisoning of goats by Prosopis sp. pods in Argentina has been recently reported (Micheloud et al., 2018).

The animals poisoned by P. juliflora pods exhibited oral dysphagia, masseter atrophy, tongue protrusion, mandible slackening, and progressive weight loss, leading to death (Câmara et al., 2009; Almeida et al., 2017). Experimental studies concluded that lesion in cranial nervous nuclei was the primary damage and that it induced the clinical signs (Tabosa et al., 2000; Almeida et al., 2017).

This paper describes five outbreaks of nervous disease in cattle associated with consumption of Prosopis nigra pods, including clinical and epidemiological aspects of the disease, and the gross and microscopic lesions identified.