Effects of tilmicosin on acute undifferentiated respiratory tract disease in newly arrived feedlot cattle.
OBJECTIVE
To evaluate effects of tilmicosin when used in fever-based and metaphylactic treatment programs to attenuate acute undifferentiated bovine respiratory disease (BRD) in cattle that recently arrived at feedlots, and to evaluate the effects of tilmicosin for the treatment of BRD.


METHODS
Randomized-block controlled study.


METHODS
1,639 calves from livestock auctions.


METHODS
Cattle were assigned to 3 groups. Cattle in the nonmedicated (control) group were not given antibiotics during processing. Cattle in the fever-based treatment group were given tilmicosin (10 mg/kg [4.5 mg/lb] of body weight, s.c.) during processing when their rectal temperature was > or = 40 C (104 F). All cattle in the metaphylactic treatment group were given tilmicosin (10 mg/kg, s.c.) during processing. Calves with BRD were treated with tilmicosin (10 mg/kg, s.c.).


RESULTS
Morbidity rates in the metaphylactic (30.4%) and fever-based (44.7%) treatment groups were less than that for the nonmedicated group (54.8%). Mortality rate for the metaphylactic group during the first 28 days (1.1%) and during the entire study (1.7%) was less than that for the nonmedicated group (3.3 and 4.6%, respectively). Differences were not observed in therapeutic response rates among calves with BRD that were treated.


CONCLUSIONS
Fever-based and metaphylactic treatment programs that used tilmicosin decreased the prevalence of BRD and improved growth of calves. Metaphylactic treatment decreased the number of fatalities caused by BRD in high-risk calves. Fever-based treatment was less effective than metaphylactic treatment for decreasing the prevalence of BRD in newly arrived cattle.
Vogel
G J
GJ
Elanco Animal Health, Eli Lilly Co., Canyon, TX 79015, USA.
Laudert
S B
SB
Zimmermann
A
A
Guthrie
C A
CA
Mechor
G D
GD
Moore
G M
GM
D000208:Acute Disease; D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy / Q000453:epidemiology / Q000517:prevention & control*; D018942:Macrolides; D008297:Male; D009017:Morbidity; D012141:Respiratory Tract Infections / Q000188:drug therapy / Q000517:prevention & control / Q000662:veterinary*; D015645:Tylosin / Q000031:analogs & derivatives* / Q000627:therapeutic use
D000900:Anti-Bacterial Agents; D018942:Macrolides; C052319:tilmicosin; D015645:Tylosin