Advertisement

Effects of tilmicosin treatment on Pasteurella haemolytica organisms in nasal secretion specimens of calves with respiratory tract disease

Glynn H. FrankNational Animal Disease Center, USDA, Agriculture Research Service, PO Box 70, Ames, IA 50010.

Search for other papers by Glynn H. Frank in
Current site
Google Scholar
PubMed
Close
 DVM, PhD
,
Robert E. BriggsNational Animal Disease Center, USDA, Agriculture Research Service, PO Box 70, Ames, IA 50010.

Search for other papers by Robert E. Briggs in
Current site
Google Scholar
PubMed
Close
 DVM, MS
,
Raymond W. LoanDepartment of Veterinary Pathobiology, College of Veterinary Medicine, Texas Veterinary Medical Center, Texas A&M University, College Station, TX 77843.

Search for other papers by Raymond W. Loan in
Current site
Google Scholar
PubMed
Close
 DVM, PhD
,
Charles W. PurdyConservation and Production Research Laboratory, USDA, Agriculture Research Service, Bushland, TX 79012.

Search for other papers by Charles W. Purdy in
Current site
Google Scholar
PubMed
Close
 DVM, PhD
, and
Emilie S. ZehrNational Animal Disease Center, USDA, Agriculture Research Service, PO Box 70, Ames, IA 50010.

Search for other papers by Emilie S. Zehr in
Current site
Google Scholar
PubMed
Close
 MA
View More View Less

Abstract

Objective—To determine the effect of tilmicosin treatment on number of Pasteurella haemolytica (PH) organisms in nasal secretion specimens of calves with respiratory tract disease.

Animals—206 British mixed-breed beef calves, 2 to 5 months old.

Procedure—In 2 separate studies of outbreaks, calves (study 1, n = 101; study 2, n = 105) that developed respiratory tract disease after transport to a feedlot were treated with tilmicosin. Nasal secretion specimens were examined for PH organisms to determine the status of colonization.

Results—In both studies, PH serotypes A1 and A6 were isolated. In study 1, tilmicosin treatment eliminated or markedly reduced the number of PH organisms in calves on days 1, 4, and 5 after treatment. In study 2, tilmicosin treatment eliminated PH organisms in calves on days 1, 2, 5, and 6 after treatment.

Conclusions and Clinical Relevance—Overall, tilmicosin treatment increased the number of culture-positive calves that became culture-negative and decreased the number of culture-negative calves that became culture-positive for up to 6 days after treatment. Tilmicosin treatment decreased the number of PH organisms in nasal secretion specimens, which indicated that fewer PH organisms were available to infect the lungs or to infect other calves. By reducing colonization, prophylactic use of tilmicosin before transport or at the time of arrival at a feedlot is likely to reduce the incidence of acute respiratory tract disease in calves for the initial several days after arrival, which is the period when they are most susceptible to infectious organisms. ( Am J Vet Res 2000;61: 525–529)

Abstract

Objective—To determine the effect of tilmicosin treatment on number of Pasteurella haemolytica (PH) organisms in nasal secretion specimens of calves with respiratory tract disease.

Animals—206 British mixed-breed beef calves, 2 to 5 months old.

Procedure—In 2 separate studies of outbreaks, calves (study 1, n = 101; study 2, n = 105) that developed respiratory tract disease after transport to a feedlot were treated with tilmicosin. Nasal secretion specimens were examined for PH organisms to determine the status of colonization.

Results—In both studies, PH serotypes A1 and A6 were isolated. In study 1, tilmicosin treatment eliminated or markedly reduced the number of PH organisms in calves on days 1, 4, and 5 after treatment. In study 2, tilmicosin treatment eliminated PH organisms in calves on days 1, 2, 5, and 6 after treatment.

Conclusions and Clinical Relevance—Overall, tilmicosin treatment increased the number of culture-positive calves that became culture-negative and decreased the number of culture-negative calves that became culture-positive for up to 6 days after treatment. Tilmicosin treatment decreased the number of PH organisms in nasal secretion specimens, which indicated that fewer PH organisms were available to infect the lungs or to infect other calves. By reducing colonization, prophylactic use of tilmicosin before transport or at the time of arrival at a feedlot is likely to reduce the incidence of acute respiratory tract disease in calves for the initial several days after arrival, which is the period when they are most susceptible to infectious organisms. ( Am J Vet Res 2000;61: 525–529)