Lesions caused by excessive reaction to foot and mouth vaccine were observed in 1,815 out of 5,000 cattle slaughtered in a slaughterhouse under federal meat inspection. Such lesions resulted in condemnation of the affect parts of the carcasses in accordance with the Brazilian Federal Meat Inspection Regulations. The affected cattle had been vaccinated on May 2012 and then slaughtered in September of the same year. They were allotted to two groups with 1,500 (Groups 1) and 315 cattle (Group 2). Post vaccination lesions were characterized as salient, firm variable sized nodules multifocally distributed in the musculature of the lateral neck. Pus oozed at the cut surface of these nodules. Samples of 28 cattle were submitted for histopathological examination; main findings were pyogranulomas with central variable-sized clear spaces surrounded by marked infiltrate of viable and dead neutrophils, which were surrounded by epithelioid macrophages with vacuolated cytoplasm and occasional multinucleated giant cell. This inflammatory reaction was walled by abundant connective tissue infiltrated by lymphocytes and plasma cells. Samples of the lesion of six cattle were submitted to bacteriological culture with negative results. When affected carcasses went through dressing, there was an average of 1.8 and 2.0 kg of muscle tissue cut off from the carcasses respectively of Group 1 and 2. Economic losses in the farm of origin of the affected cattle was R$ 20,424.00, considering the price paid by kg of cattle for slaughter at the time of the occurrence. This amount at that time was enough to buy 29.17 weaned calves for fattening. If one considers theses 5,000 cattle vaccinated on the farm as the population at risk, the morbidity rate would be 0.36%. These results indicate that the losses due to vaccine reaction, even with no overt clinical signs, may cause important economic losses.
Economic losses; vaccine reaction; foot-and-mouth disease; oil adjuvant; vaccine granulomas; cattle
