An outbreak of perirenal oedema syndrome in cattle associated with ingestion of pigweed (Amaranthus hybridus L.).

Forty seven of 150, 15-month-old long weaners died of an acute renal disease syndrome following introduction into an old maize field with a heavy stand of Amaranthus spp. The clinical syndrome was characterised by sudden onset neurological disease with ataxia and recumbency. Subcutaneous oedema, ascites and perirenal oedema with urine odour were the major gross necropsy findings. Renal histopathology revealed marked coagulative renal tubular necrosis of the proximal and distal straight tubules with intertubular haemorrhage. Acute renal failure and perirenal oedema has been described in cattle, pigs, horses and sheep associated with the ingestion of A. hybridus L. and A. retroflexus L. This perirenal oedema syndrome has been widely reported in the Americas, while in South Africa intoxication with the amaranths has only previously been associated with nitrate and possibly oxalate poisoning in cattle.