Toxic myopathy in dairy goats caused by spontaneous ingestion of Senna obtusifolia

Abstract

Senna obtusifolia, commonly known as sicklepod, has become widely distributed across tropical and subtropical regions globally. This aggressive weed of rangelands is capable of outcompeting palatable grasses and suppressing the growth of desirable pasture species. In Brazil, intoxication by S. obtusifolia is rarely reported in small ruminants. This study reports the epidemiology, clinical signs, biochemistry, and gross and microscopic lesions associated with spontaneous S. obtusifolia intoxication in goats from northeastern Brazil. The disease presented with a subacute course, characterized mainly by muscle weakness, reluctance to move, and a stiff or uncoordinated gait, which progressed to permanent recumbency. The activities of plasma creatine kinase were strongly increased. The gross findings included asymmetrical, pale areas in the skeletal muscles, and histologically, the lesions consisted of severe segmental myofiber degeneration and necrosis. Several specimens of seeding S. obitusifolia were found invading the goats' grazing areas, which presented evidence of having been consumed. Normally, goats do not eat the plant, and this outbreak was triggered primarily by the absence of adequate weed control and heavy infestation by S. obtusifolia in the goats' grazing areas. The poor nutritional management practices adopted on the farm likely contributed to the ingestion of S. obtusifolia under conditions of forage scarcity. These findings reinforce the importance of proper pasture management, nutritional supplementation, and early clinical recognition in preventing and mitigating toxic myopathies associated with S. obtusifolia in goats.

Keywords: Muscle necrosis; Senna obtusifolia; Sicklepod; Small ruminant; Toxic plants.