Subchronic Administration of Technical Pentachlorophenol to Lactating Dairy Cattle: Performance, General Health, and Pathologic Changes1,2

Abstract

Technical grade pentachlorophenol (penta) was fed subchronically to lactating dairy cattle to establish whether exposure approximating farm environments containing substantial penta-treated wood represents a hazard to animal health. Four Holstein cattie in early lactation were fed .2mg penta/kg body weight per day for 75 to 84 days followed by 2mg penta/kg body weight per day for 56 to 60 days. Each treated cow was paired with a control cow of equivalent stage of lactation. Milk production, feed intake, and body weight were not affected by either dose except that treated cattle were more efficient converters of feed to milk during the early stage of the 2mg/kg period. Neither milk fat production nor somatic cell count in milk were affected by exposure to penta. Postmortem examination revealed enlargement of liver, lungs, kidneys, and adrenals and thickening of the urinary bladder wall. Chronic interstitial nephritis and subacute urocystitis were the major pathologic changes in penta-treated cattle. In vitro testing of kidney slices confirmed significant loss of renal function. The relationship of lesions to administration of penta is not clear.