An evaluation of chlortetracycline feed additive for prevention or treatment of porcine prouferative enteropathy (PE or ileitis)

摘要

Porcine Proliferative Enteropathy (PE or ileitis) is an important enteric disease of grow/finish pigs worldwide. In vitro sensitivity testing has shown the MIC of chlortetracycline (CTC) against Lawsonia intracellularis to be very low (< 1 ppm). Hamster challenge models have also shown CTC to be an effective therapeutic for prevention/control of ileitis. The objective of this study was to evaluate the in vivo effectiveness of a granular formulation of feedgrade CTC in preventing or treating ileitisin swine challenged with a mucosal homogenate containing L. intracellularis organisms. One hundred twenty five approximately 32 day old pigs averaging 12.3 kg (27 1bs) from a high health 3 site farm of known disease status were used. The pigs were randomized into 5 treatment groups of 5 pigs per pen, replicated 5 times per treatment. Treatment groups included nonchallenged, nonmedicated (negative) controls, challenged, nonmedicated (positive) controls, challenged, CTC 22 mg/kg (10 mg/lb) body weight starting 4 days prechallenge and continued for 14 days, followed by CTC 110 ppm (100 gm/ton) through Day 35, challenged, CTC 110 ppm (100 gm/ton) starting 4 days prechallenge and continued through Day 35, and challenged, CTC 22 mg/kg (10 mg/lb) bodyweightstarting when clinical signs were first seen and continued for 14 days, then CTC 110 ppm (100 gm/ton) through Day 35. Pigs were orally dosed on Day -1 and Day 0 with a mucosal homogenate containing 6.3 X 10~8 L. intracellularis organisms. Parameters measured included individual pig weights, daily feed disappearance, mortality, abdominal appearance and pig attitude. Fecal samples were collected for PCR analysis. Gross intestinal lesion scores were recorded and histopathology was conducted.