- - - Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran
- - - Gratuated student, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran
- - - Department of Pathobiology, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran

Mastitis caused by Escherichia coli (E. coli) is one of the most common causes of environmental mastitis in dairy cows, which can impact on the milk quality. In this randomized clinical trial, dairy cattle with naturally acquired acute E. coli mastitis (between January 2014 and December 2016, n = 100) were treated with ceftiofur hydrochloride (group A) or placebo (group B) and their rates of clinical recovery 5 days after starting treatment were compared. The cows were randomized into two groups with a 1:1 allocation ratio on the basis of their ear tag numbers. All cows concurrently received supportive measures such as anti-inflammatory treatment, fluid therapy, and frequent milking. Of the 50 cows in the antibiotic group, 41 (82%) recovered clinically. Of the 50 cows in the placebo group, two (4%) recovered (P < 0.01). The rates of quarter recovery in the two groups on day 5 were 31.7% and 0%, respectively (P < 0.01). Our results suggest that even when treated with intensive supportive therapy, cows with naturally acquired acute E. coli mastitis will exhibit poor recovery rates if they are not treated with an effective antibiotic such as ceftiofur hydrochloride. Regarding the presence and shedding of the E. coli microorganisms in the milk, it should be considered in relation to public health.

dairy cow, acute mastitis, Escherichia coli, Treatment, ceftiofur