Peripheral blood leukocyte subpopulation of dairy cows with digital dermatitis and effect of hoof trimming with antibiotic treatment.

In the present study, 30 cows were used to evaluate the changes in the peripheral blood leukocyte subpopulation of dairy cows with digital dermatitis (DD) following hoof trimming and antibiotic treatment. The cows were divided into two groups; 18 cows (DD group) had DD on both hind feet, and 12 cows (control group) had four feet with no clinical abnormalities. The DD group was further divided into two groups based on the treatment; the antibiotic group (8 cows) was treated with only 2% lincomycin liquid spray once daily for 3 days, and the trimmed group (10 cows) received trimming of hooves as well as treatment with 2% lincomycin liquid spray. The plasma cortisol concentration was significantly higher in both DD groups before treatment than in the control group, and it decreased significantly after hoof trimming in the trimmed group. The number of CD3(+), CD4(+), WC1(+) and CD21(+) cells in both DD groups before treatment was significantly lower than that of the control group. The number of CD3(+), CD4(+), WC1(+) and CD21(+) cells in the trimmed group increased after treatment. These results indicated that cows with DD suffer from stress and reduced number of T and B cells. Treatment of DD with both hoof trimming and 2% lincomycin liquid spray was effective for reducing the stress and bringing the immune cell number back to the normal range.