Evaluation of the therapeutic activity of tulathromycin against swine respiratory disease on farms in Europe.

The clinical efficacy of tulathromycin in the treatment of natural outbreaks of swine respiratory disease (SRD) was evaluated at five European sites. Pigs (1 to 6 months of age) exhibiting clinical signs of SRD were treated intramuscularly with tulathromycin (n = 247) at 2.5 mg/kg on day 0 versus either tiamulin (n = 102) at 15 mg/kg on days 0, 1, and 2 (Germany, the Netherlands, and the United Kingdom) or florfenicol (n = 20) at 15 mg/kg on days 0 and 2 (France). Actinobacillus pleuropneumoniae, Pasteurella multocida, and Mycoplasma hyopneumoniae infections were the most frequently diagnosed pathogens. For both tulathromycin-treated animals and those treated with tiamulin or florfenicol, there were significant (P = .0001) reductions in mean rectal temperature and the severity of abnormal clinical signs on days 2 and 10 compared with day 0. There were no significant differences (P > .05) between treatments in average daily weight gain. Tulathromycin was found to be safe and highly effective in the treatment of natural outbreaks of SRD.

Minimum inhibitory concentrations of tulathromycin against respiratory bacterial pathogens isolated from clinical cases in European cattle and swine and variability arising from changes in in vitro methodology.

The in vitro activity of tulathromycin was evaluated against common bovine and porcine respiratory pathogens collected from outbreaks of clinical disease across eight European countries from 1998 to 2001. Minimum inhibitory concentrations (MICs) for one isolate of each bacterial species from each outbreak were determined using a broth microdilution technique. The lowest concentrations inhibiting the growth of 90% of isolates (MIC90) for tulathromycin were 2 microg/ml for Mannheimia (Pasteurella) haemolytica, 1 microg/ml for Pasteurella multocida (bovine), and 2 microg/ml for Pasteurella multocida (porcine) and ranged from 0.5 to 4 microg/ml for Histophilus somni (Haemophilus somnus) and from 4 to 16 microg/ml for Actinobacillus pleuropneumoniae. Isolates were retested in the presence of serum. The activity of tulathromycin against fastidious organisms was affected by culture conditions, and MICs were reduced in the presence of serum.