Suspected citrus pulp toxicosis in dairy cattle

Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Tech, Blacksburg 24061-0442, USA.

Thirteen lactating dairy cows from a herd of 650 died over a 6-week period. Most animals were down in milk production at 1 milking and were found dead at the next milking. Two cows had elevated heart rate and enlarged mandibular lymph nodes. Two others had azotemia, elevated heart rate, hyperglycemia, and weight loss. Necropsy of 10 cows revealed hemorrhages on the intestinal serosa and epicardium, lymphadenopathy, interstitial nephritis, small intestinal hemorrhage, and interstitial pneumonia. Histopathology showed lymphocytic to lymphogranulomatous inflammation in the heart, spleen, kidney, lymph nodes, liver, lung, pancreas, and adrenal gland. Phlebitis was present in 2 livers. The lesions resembled those of hairy vetch toxicosis, but no vetch was being fed. Similar lesions have been reported with the feeding of citrus pulp. Citrus pulp was being fed to the lactating cows and had been added to the diet 6 weeks before the first death. The syndrome resolved with elimination of citrus pulp from the diet.