Are environmental conditions responsible for animal-plant carcinogen interaction? A study relating to enzootic bovine haematuria

Summary Enzootic bovine haematuria (EBH) is a disease of cattle characterised by intermittent presence of blood in their urine and tumours of mixed origin in the urinary bladder. No consensus exists on the etiology of the disease, though bracken fern (Pteridium aquilinum) and/or papilloma virus have been implicated. There are areas where the malady is absent but the putative incrementing factor(s) are present. This raised the possibility of investigations into the interplay of environmental factors which might be conducive to the possible exposures to carcinogens in some regions. A comparative study of areas where the disease is prevalent (enzootic), and where it is absent (nonenzootic), to determine the type of vegetation (including ferns), the grazing patterns, the animal husbandry practices and the agroclimatic conditions in animal-plant interaction, is presented. Most of the ferns are common to both enzootic and nonenzootic areas. Bracken fern, a known source of carcinogens is present in both enzootic and nonenzootic areas. Ferns, with the exception of Athyrium spp. are not acceptable to the cattle when offered, being smelt and rejected. Ferns are not used as bedding material in the enzootic area studied.The authors conclude that different environmental conditions and animal husbandry practices may result in the cattle in the enzootic areas being exposed to carcinogenic brackens and other ferns at a time when there is a shortage of other alternative feedstuffs.Drs Dawra, Sharma and Krishna work at the Palampur Regional Station of the Indian Veterinary Research Institute. Correspondence should be addressed to Dr Rajinder K. Dawra.