Clinical features of renal tubular dysplasia, a new hereditary disease in Japanese Black cattle

A new hereditary disease characterised by renal failure, poor growth and lo ng hooves in Japanese Black cattle (wagyu) has been recognised in a region of central Japan since 1990. The number of calves affected has increased gr adually, with the incidence reaching 17 of 485 (3-51 per cent) in 1995. Alm ost all the calves were slightly undersized at birth, and repeatedly had di arrhoea during the neonatal period. They began to show signs of growth reta rdation with proportional body and elongation of the hooves from about two to five months of age, but they had an almost normal or only slightly decre ased appetite. The concentrations of urea nitrogen, creatinine and inorgani c phosphorus in serum were high, and the affected calves excreted diluted u rine frequently. Among 25 cases, the urine of 21 contained occult blood, 24 contained protein and two contained glucose. In 29 calves observed for 30 to 130 days, the course of the disease varied; in 21 of them it remained un changed, six became gradually worse and two became severely debilitated and died. The disease was diagnosed as renal tubular dysplasia by histopatholo gical examination.