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Title: THE EFFECT OF DANOFLOXACIN AND TILMICOSIN ON BODY TEMPERATURES IN BEEF CALVES WITH INDUCED PASTEURELLA (MANNHEIMIA) HAEMOLYTICA PNEUMONIA

Author
item FAJT, VIRGINIA - IOWA STATE UNIVERSITY
item APLEY, MICHAEL - IOWA STATE UNIVERSITY
item Brogden, Kim
item SKOGERBOE, TERRY - PFIZER ANIMAL HEALTH
item KARLE, VALERIE - PFIZER ANIMAL HEALTH
item CHIN, YA-LIN - PFIZER ANIMAL HEALTH

Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2003
Publication Date: 5/1/2004
Citation: Fajt, V.R., Apley, M.D., Brogden, K.A., Skogerboe, T.L., Karle, V.K., Chin, Y. 2004. The effect of danofloxacin and tilmicosin on body temperatures in beef calves with induced pasteurella (mannheimia) haemolytica pneumonia. American Journal of Veterinary Research. 65(5):610-615.

Interpretive Summary: Pneumonia caused by Mannheimia (Pasteurella) haemolytica is a leading cause of mortality and morbidly in feedlot cattle, often resulting in significant economic losses to the producer. Body temperature is a commonly used parameter for evaluating the health status of cattle and the presence of fever implies and correlates with the presence of bacteria, like M. haemolytica, involved in respiratory disease. The objective of this study was to examine the effects of danofloxacin or tilmicosin treatment of induced M. haemolytica pneumonia in beef calves on continuously recorded body temperature. For this, pneumonia was induced intrabronchially using log-phase cultures of M. haemolytica. At 20 hours post-challenge, animals were treated with saline, danofloxacin or tilmicosin. Radiotransmitters were implanted intravaginally, and body temperatures were monitored from 66 hours prior to challenge until necropsy at 72 hours after treatment. Danofloxacin and tilmicosin did not differ in their effect on mean 3-hour interval body temperatures, but significantly decreased temperatures as compared to saline-treated infected animals. Therefore, normal daily variation in body temperature must be considered in the face of respiratory disease when clinical evaluation of feedlot animals is required.

Technical Abstract: Objective: To examine the effect of danofloxacin and tilmicosin treatment of induced P. haemolytica pneumonia in beef calves on continuously recorded body temperature. Animals: 32 weaned Angus-cross beef heifers (160-220 kg) from a single ranch with no recent history of respiratory disease or antimicrobial therapy. Procedure: Pneumonia was induced intrabronchially using log-phase cultures of Pasteurella haemolytica. At 20 hours post-challenge, animals were treated with saline, danofloxacin or tilmicosin. Radiotransmitters were implanted intravaginally, and body temperatures were monitored from 66 hours prior to challenge until necropsy at 72 hours after treatment. For each animal, a baseline temperature was established based on pre-challenge body temperature. The area under the curve (AUC) of the temperature-time plot was calculated for 3-hour intervals, and compared across treatment groups. Mean 3-hour interval temperatures were also calculated. Results: Areas under the curve for 3-hour intervals were not significantly different for any of the time intervals when challenged-treated animals were compared. Analysis of the mean 3-hour interval temperatures showed significantly higher temperatures for saline-treated as compared to antimicrobial-treated animals for the majority of the time intervals, but no differences were found between the danofloxacin- or tilmicosin-treated animals. The circadian rhythm of pre-challenge temperatures returned at approximately 48 hours after challenge. Conclusions: Danofloxacin and tilmicosin did not differ in their effect on mean 3-hour interval body temperatures, but significantly decreased temperatures as compared to saline-treated controls. Clinical Relevance: Normal daily variation in body temperature must be considered in the face of respiratory disease when clinical evaluation of feedlot animals is required.