The effect of tilmicosin in minimizing atrophic rhinitis, pneumonia, and pleuritis in swine

Linda B. Olson, DVM, MS; Lennart R. Bäckström, DVM, PhD

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Objective: To determine whether nursery pigs fed tilmicosin for 3 weeks would be protected against progressive atrophic rhinitis (PAR) when housed with clinically diseased pigs.

Methods: Recipient pigs, exposed to donor pigs that demonstrated clinical signs of PAR, either did not (NME group) or did (ME group) receive tilmicosin in feed for 3 weeks; a third Control group was neither exposed nor medicated. Pig weights and nasal swabs for bacterial culture were collected on study days 0, 21, and 42. Feed intake was also monitored. On study day 21, all medication was removed from the ME feed and the donor animals were submitted for postmortem examination. On study day 42, NME, ME, and Control pigs were euthanized and submitted for postmortem examination. Snout scores, pneumonia, and pleuritis were assessed grossly and scored. Turbinate perimeter ratios were also scored using a digital image processing and analysis program.

Results: Overall, rate of gain was greater in the Control pigs than in either the ME or NME pigs. Average daily gain and feed intake were significantly greater (P<.05) in the ME pigs compared to the NME pigs throughout the study. Feed efficiency did not differ significantly among groups. All recipient pigs were culture negative for Bordetella bronchiseptica and Pasteurella multocida on day 0. The Control pigs remained negative for P. multocida types A and D throughout the study and only one pig was positive for B. bronchiseptica by culture at the end of the study. A higher percentage of NME pigs than ME pigs were culture positive for P. multocida on days 21 and 42. From study days 21-42, there was a marked increase of positive P. multocida type A cultures in ME pigs. At slaughter, Control pigs showed no gross pneumonia lesions and had lower visual snout scores compared to both the ME and NME pigs. Visual atrophic rhinitis scores were significantly higher (P<.05) in the NME pigs compared to the ME pigs.

Implications: Treatment with tilmicosin resulted in lower snout scores and better growth in ME pigs than in NME pigs.

Keywords: progressive atrophic rhinitis, Pasteurella multocida, tilmicosin

RIS citationCite as: Olson LB, Bäckström LR. The effect of tilmicosin in minimizing atrophic rhinitis, pneumonia, and pleuritis in swine. J Swine Health Prod 2000;8(6):263-268.

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