Intramuscular administration of ceftiofur sodium versus intramammary infusion of penicillin/novobiocin for treatment of Streptococcus agalactiae mastitis in dairy cows.
OBJECTIVE
To determine the efficacy of intramuscular administration of ceftiofur sodium as treatment for intramammary infections attributable to Streptococcus agalactiae, compared with that for a standard treatment of intramammary infusion of penicillin/novobiocin.


METHODS
Prospective, randomized, controlled trial.


METHODS
72 lactating Holstein cows with intramammary infections caused by S agalactiae from 5 commercial dairies in Michigan.


METHODS
In 36 of 72 infected cows, ceftiofur was administered (2.2 mg/kg of body weight, IM, q 24 h) for 5 days; 150 mg of novobiocin and 100,000 U of procaine penicillin G was infused daily into each mammary gland of the other 36 cows for 2 days. Milk samples were collected aseptically at approximately 4 and 8 weeks after initial treatment. If cows were determined to be infected at 4 weeks after initial treatment, the treatment was repeated.


RESULTS
The cure rate at 4 weeks (91.7%) and at 8 weeks (96.8%) after initial treatment for the penicillin/novobiocin-treated cows was significantly (P < 0.0001) higher, compared with that of the ceftiofur-treated cows (2.8 and 9.1%, respectively). Somatic cell counts were significantly (P < 0.0001) lower in the penicillin/novobiocin-treated group after treatment.


CONCLUSIONS
Intramuscular administration of ceftiofur is not efficacious as a treatment to eliminate intramammary infections caused by S agalactiae and should not be used to reduce the prevalence of this organism in dairy herds.
Erskine
R J
RJ
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824, USA.
Bartlett
P C
PC
Johnson
G L
GL
Halbert
L W
LW
D000818:Animals; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D002511:Cephalosporins / Q000008:administration & dosage*; D004359:Drug Therapy, Combination / Q000008:administration & dosage*; D005260:Female; D007263:Infusions, Parenteral / Q000662:veterinary; D007273:Injections, Intramuscular / Q000662:veterinary; D016015:Logistic Models; D008321:Mammary Glands, Animal; D008414:Mastitis, Bovine / Q000188:drug therapy*; D008892:Milk / Q000166:cytology; D009675:Novobiocin / Q000008:administration & dosage; D010402:Penicillin G Procaine / Q000008:administration & dosage; D010406:Penicillins / Q000008:administration & dosage; D013290:Streptococcal Infections / Q000188:drug therapy / Q000662:veterinary*; D013292:Streptococcus agalactiae; D016896:Treatment Outcome
D002511:Cephalosporins; D010406:Penicillins; D009675:Novobiocin; D010402:Penicillin G Procaine; C053503:ceftiofur