OUTBREAK OF FIBRINOUS PNEUMONIA IN RECENTLY WEANED BEEF-CALVES IN SOUTHERN QUEENSLAND

Objective To describe an outbreak of fibrinous pneumonia in 331 recent ly weaned beef calves on two properties in the Miles district in south ern Queensland. Description of the herd The affected calves came from three groups: 88 recently weaned calves purchased at Casino NSW saleya rds on 29 April 1994, 91 recently weaned carves purchased at Inverell NSW saleyards on 11 May 1994 and 152 homebred carves weaned on 18 May 1994 off the owner's cows. All carves were Hereford and Hereford cross . Investigation The two groups of purchased carves (the Casino-Inverel l weaners) were mixed together and moved to another recently purchased property on May 19 after handling on May 18. The homebred weaners wer e not mixed with the Casino-lnverell weaners, but had nose-to-nose con tact for one night via a 3 m gateway while yarded on May 18. By May 25 , an outbreak of acute undifferentiated bovine respiratory disease was evident among all 331 carves and two were dead. The morbidity risk in all three groups was 90%, suggesting the three groups of calves were equally susceptible. Five calves died during the outbreak, giving a cr ude mortality rate of 1.5% (5/331), with necropsy of three calves show ing they died of fibrinous pneumonia. Treatment of all calves with a s ingle injection of 20 mg/kg of long acting oxytetracycline lead to rap id clinical improvement in affected calves, and appeared to prevent fu rther mortality. Mortality clustered, with three of the four dead purc hased carves coming from one vendor of the Inverell sale. Conclusions Fibrinous pneumonia can occur after weaning in beef calves in Australi a. It is highly contagious among groups of recently weaned calves.