Pattern and determinant of antibiotics used on broiler farms in Songkhla province,southern Thailand

The study was conducted on antibiotics use and determinant of use on 101 broiler farms in Songkhla province, Thailand. Ninety-six farms used the broiler production system under contracting companies and 5 farms were independently operated. All of the farms used antibiotics for disease prevention. Twenty agents in 9 classes of antibiotics were used; the most commonly used ones were enrofloxacin, amoxicillin, doxycycline, colistine and roxithromycin. There were 33 patterns of antibiotics use, the most frequently used being the combination of amoxicillin-enrofloxacin (21.18%). Cluster analysis suggested that the variation in antibiotic usage is mostly under the influence of the companies. Regulation of antibiotics use thus should focus on the company level.     

Pharmacokinetics of cefaronide, ceftriaxone and cefoperazone in sheep

The pharmacokinetics of cefaronide (16 gm/kg dose), ceftriaxone and cefoperazone (47 gm/kg dose), after intravenous (i.v.) administration were determined in six Merino ewes. The mean values for terminal half life, steady state volume of distribution Vd(ss), renal clearance (ClR) and total body clearance (ClB) for cefaronide were 1.5 h, 0.39 l/kg, 0.06 l/h/kg and 0.16 l/h/kg, for ceftriaxone; 1.7 h, 0.30 l/kg, 0.08 l/h/kg, and 0.22 l/h/kg, and 0.7 h, 0.16 l/kg, 0.02 l/h/kg and 0.16 l/h/kg for cefoperazone, respectively. After 5.5 h, approximately 42% cefaronide, and after 8 h, approximately 37% ceftriaxone and 13% cefoperazone, was excreted in urine. The non-renal elimination of ceftriaxone and cefoperazone appeared to be more rapid in sheep than is reported in man. Cefaronide was excreted largely unchanged in the urine of sheep. Therefore, the elimination of cefaronide in sheep was similar to that found in man. Cefaronide was well distributed in sheep, whereas ceftriaxone and cefoperazone appeared to be distributed to a lesser degree. These findings underline the different disposition of drugs in different species.     

Effect of shock strength on survival and acute cardiac damage induced by open-thorax defibrillation of dogs

The safety of open thorax defibrillation with single damped sine-wave shocks and 6-cm-diameter electrodes was evaluated in healthy anesthetized dogs. Twenty-one dogs were allotted to 6 groups: Group A were nonshocked controls and groups B through F were given single shocks of 4-, 7-, 12-, 19-, or 32-fold, respectively, greater than a defibrillation threshold dose (30 mA/g of heart). Immediate postshock death resulted in group F dogs; group A through E dogs survived and were killed after 2 days. The incidence and severity of cardiac morphologic damage increased with shock strength (mild damage occurred in 1 of 3 dogs in group C and in 3 of 4 dogs in group D and severe damage occurred in 2 of 3 dogs in group E). The cardiac lesions were characterized grossly and microscopically. In dogs that died immediately after shocking, damage was apparent as pale circular zones of edema and myofibrillar degeneration in the ventricular free walls beneath the electrode placement sites on the cardiac surface. In the dogs that survived 2 days, the defibrillator-induced areas of myocardial necrosis and calcification were concentrated in arc or ringlike patterns beneath the periphery of the electrode placement sites. All dogs that were studied 2 days after shocking had mild fibrinous pericarditis. Postshock electrocardiographic changes were not good indicators of cardiac damage because the mild epicardial inflammatory reaction associated with the surgical procedure produced large ST and T wave changes which masked any changes associated with myocardial necrosis induced by the electric shocks. It was concluded that a substantial safety margin exists between the required defibrillation threshold shock dose and the large shocks required to produce marked cardiac damage or death in healthy dogs.