Colic caused by Panicum maximum toxicosis in equidae in northern Brazil.

The research focuses on the effects of Panicum maximum cultivars on equine species in the Amazon region of northern Brazil where it causes severe colic and death.

Overview of the Study

• The study involved observing outbreaks of disease in horses and mules that had been grazing on sprouting pastures of Panicum maximum cultivars during the rainy season.
• The research spanned eight separate disease outbreaks, involving 153 equidae (a group of mammals which includes horses, donkeys and zebras) of which 52 were affected by colic and subsequently, 19 of them died.

Clinical Signs and Manifestations

• The affected equidae exhibited clinical signs of colic and abdominal dilation within a period of 12 hours to 4 days post-exposure.
• Serum urea nitrogen and creatinine concentrations were occasionally elevated, though other serum indicators like gamma-glutamyl transferase and aspartate aminotransferase remained within usual ranges.

Pathological Findings

• Upon gross examination, the major lesions were concentrated within the digestive system, including severe hemorrhages and occasional erosions and ulcerations of the mucosal linings of the stomach, small intestine, and large intestine.
• The urinary bladder was rarely affected but indicated similar symptoms.
• Microscopic investigations unveiled diffuse lymphoplasmacytic gastritis and enteritis with symptoms of severe congestion, hemorrhage, and occasional necrosis and ulceration of the epithelium.
• Sporadic lymphocellular necrosis was also detected in the gut-associated lymphoid tissue; tubular nephrosis was noted in some animals.
• Pathological anomalies were also detected in the liver, including degeneration and occasional necrosis of the bile duct cells and degeneration of hepatocytes.

Toxicity Investigation

• Investigation of toxins within the Panicum maximum cultivars negated the presence of diosgenin- and yamogenin-based saponins, toxic elements usually associated with the plant toxicity.
• The concentration of oxalates, another potential contributing factor, was also found within normal ranges for the species, suggesting other, yet unknown factors, contributing to toxicity.
• The exact toxins and the reason why the Panicum maximum cultivars are toxic in this region of Brazil remain unknown.