Aujeszky's disease in captive bears

Five of eight bears died during an outbreak of Aujeszky's disease in a beve lling circus in the north of Spain. The bears had been fed on a diet which included raw pigs' heads. One of three Himalayan bears and a Kodiak bear di ed acutely with signs of the disease. One of four polar bears died acutely without signs, another died with signs of Aujeszky's disease while it was b eing treated, and a third died with enteritis and disseminated intestinal c oagulation some time later without showing signs of the disease. A fourth p olar bear recovered from the same gastrointestinal problem without showing signs of the disease. Although one of the two surviving Himalayan bears sho wed some signs referrable to Aujeszky's disease, the results of tests for n eutralising antibodies were negative. Two of the polar bears, the Himalayan bear and the Kodiak bear were examined postmortem and three of them were e xamined histologically. No lesions referable to Aujeszky's disease were fou nd. The tissues from one female polar bear were examined and shown to be po sitive for Aujeszky's disease virus by virus isolation, polymerase chain re action, electron microscopy and fluorescent antibody tests. The DNA of the isolate was shown to be similar to that of the strains of the virus circula ting in pigs in northern Spain some years earlier.