The aim of this study was to evaluate tiamulin hydrogen fumerate (THF) as an in-feed antibiotic for control of porcine respiratory disease complex (PRDC) that includes infection with Mycoplasma hyopneumoniae (M hyo).
Two studies were performed, each of 17 days duration. Study One evaluated the effect of treatment with THF at 137.5 and 165.0 ppm on the clinical signs associated with PRDC and pneumonia lesion resolution in 219 nursery pigs multi-sourced from two herds affected by PRDC whereas Study Two examined similar parameters in 180 six-week-old single-sourced naive pigs were challenged with M hyo.
In Study One, pigs exhibiting clinical signs of PRDC and treated with THF at 165.0 ppm showed significantly better treatment success than did controls, defined as body temperature < 40ºC and respiratory and depression scores < 2 on Day 17 (P < .001), with lower total percent pneumonia lesions (P < .001) and mortality (P < .05). In the THF 137.5 ppm group, total percent pneumonia lesions (P < .001) and mortality (P < .05) were lower than in controls. Treatment success did not differ between the THF 137.5 ppm group and the controls.
In Study Two, all pigs were positive for M hyo infection by bacterial isolation (Table 4) after M hyo challenge and necropsy. Total percent pneumonia lesions was lower in the THF 165.0 ppm group (11.76%; P < .001) and 137.5 ppm group (16.02%; P < .05) than in controls (22.35%). There were no significant differences in treatment success, percent mortality, or clinical assessment scores performed on Day 17.
In Study One, all pigs treated with THF survived to study termination, while three pigs in the non-medicated control group died (5% mortality). Previous reports show that untreated pigs infected with PRDC experience mortality rates ranging from 2% to 20%, further evidence that the PRDC outbreak in Study One was typical of that in commercial swine settings.9
Under the conditions of this study, in-feed tiamulin hydrogen fumerate produces a positive clinical benefit in pigs experiencing PRDC or experimentally challenged with M hyo.
Roberts E, Hammer JM, Lechtenberg K, et al. Investigation of tiamulin hydrogen fumerate in-feed antibiotic for the control of porcine respiratory disease complex that includes Mycoplasma hyopneumoniae. J Swine Health Prod. 2011;19(4):218?225.