ABSTRACT
Twenty-four of 57 calves fed a diet containing 33% cotton seed meal (CSM) died between 7 and 15 weeks of age. Initial deaths were not accompanied by premonitory signs, but after CSM withdrawal most calves developed rough coats, anorexia, weakness, ascites and subcutaneous oedema. Those that died had large volumes of serous fluid in the body cavities, hard livers of 'nutmeg' appearance, and pulmonary congestion. Histopathologically the livers showed periacinar necrosis in acute cases and periacinar fibrosis in chronic cases. Lungs from several calves had oedema, haemosiderosis and fibrosis in some pulmonary vessels. Atrophy of myocardial fibres was present in most cases. The concentration of free gossypol in the diet was 100 to 220 mg/kg. Ante-mortem and post-mortem findings supported a diagnosis of gossypol poisoning. The deaths continued for 4 weeks after withdrawal of CSM from the diet.
Subject(s)
Cattle Diseases/chemically induced , Gossypol/poisoning , Age Factors , Animals , Anorexia/chemically induced , Anorexia/epidemiology , Anorexia/veterinary , Ascites/chemically induced , Ascites/epidemiology , Ascites/veterinary , Atrophy/chemically induced , Atrophy/epidemiology , Atrophy/veterinary , Cattle , Cattle Diseases/diagnosis , Cattle Diseases/epidemiology , Disease Outbreaks/veterinary , Edema/chemically induced , Edema/epidemiology , Edema/veterinary , Fibrosis/chemically induced , Fibrosis/epidemiology , Fibrosis/veterinary , Liver/drug effects , Liver/pathology , Lung/drug effects , Lung/pathology , Lung Diseases/chemically induced , Lung Diseases/epidemiology , Lung Diseases/veterinary , New South Wales/epidemiology , Poisoning/diagnosis , Poisoning/epidemiology , Poisoning/veterinary , Skin Diseases/chemically induced , Skin Diseases/epidemiology , Skin Diseases/veterinaryABSTRACT
A prospective study of the incidence and severity of congenital deformities of calves, attributable to maternal infection by Akabane virus, was carried out on a population of 174 susceptible animals that were between one and nine months pregnant at the time of infection. The study was carried out in the Hunter Valley of New South Wales during 1983, after an epidemic of Akabane virus infection in late February to early March 1983. The incidence of virus-induced abnormalities in calves and fetuses was 17.8 per cent (31/174). The highest incidence of abnormalities occurred during the third and sixth months of gestation (27 to 29 per cent). The earliest abnormality was observed after infection at 76 days of gestation, and the last after infection at 249 days. The development of the pathological entities of hydranencephaly/porencephaly and arthrogryposis were found to be quite distinct. Cases of hydranencephaly and porencephaly developed after infection between 76 and 104 days of gestation whereas arthrogryposis developed after infection between 103 and 174 days of infection. It was concluded that the type of congenital deformity produced by maternal infection with Akabane virus was dependent on the stage of fetal development at the time of infection. The data suggest that the infection was transplacental and that fetuses of less than two months of age were protected from infection.
