A multilocation clinical trial in lactating dairy cows affected with clinical mastitis to compare the efficacy of treatment with intramammary infusions of a lincomycin/neomycin combination with an ampicillin/cloxacillin combination
Deluyker, H.A.; Chester, S.T.; Oye, S.N. van
Journal of Veterinary Pharmacology and Therapeutics 22(4): 274-282
The efficacies of intramammary infusions in quarters affected with clinical mastitis of a formulation containing 330 mg lincomycin and 100 mg neomycin in a 10-ml aqueous solution (LINCOCIN FORTE S.) and a formulation containing 75 mg ampicillin and 200 mg cloxacillin in an oil suspension (AMPICLOX) were compared in lactating cows. This study was designed as a multicentre clinical trial involving investigators in France, Germany and Belgium and carried out according to the European Commission guidelines on Good Clinical Practices. Cows in the herds were monitored for clinical mastitis. When evidence of clinical mastitis was detected in a single quarter, a pretreatment milk sample was collected from the affected quarter. After milk sampling, the cow was assigned to one of the 2 treatment groups at random and treated with an intramammary infusion of one syringe of either LINCOCIN FORTE S or AMPICLOX for 3 successive milkings in the mastitic quarter. At 4-5, 13-15 and 20-22 days after first infusion, the veterinarian returned to the farm to conduct a clinical examination and collect milk samples from the affected quarter. Milk samples were cultured for mastitis organisms and somatic cell count (SCC) was measured. Following a 10-month study period, 256 cases were enrolled in the study. 232 and 189 cases were examined for clinical cure and for clinical-plus-bacteriological cure, respectively. The proportions of cases cured clinically and cured clinically-plus-bacteriologically were compared between the treatment groups. Somatic cell count differences between treatment groups were also tested. The clinical cure rate for LINCOCIN FORTE S (62.5%) was significantly better than for AMPICLOX (51.8%) (P = 0.035). The clinical-plus-bacteriological cure rate was also significantly better for LINCOCIN FORTE S (38.1%) than for AMPICLOX (21.7%) (P = 0.005). Among bacteriologically cured cases, the SCC declined in both treatment groups but the SCC was significantly higher for the AMPICLOX group than for the LINCOCIN FORTE S group (P = 0.036). In conclusion, clinical cure rate, clinical-plus-bacteriological cure rate, and SCC level were significantly better with LINCOCIN FORTE S than for AMPICLOX.