Animal-based measurements of the severity of mastitis in dairy cows.

A range of clinical parameters were studied to assess their usefulness as objective markers of the severity of clinical mastitis in dairy cows. Cows with moderate clinical mastitis had significantly higher rectal temperatures and heart and respiratory rates than cows with mild clinical mastitis or control cows. The difference in temperature between quarters did not vary significantly between the control cows and the cows with mastitis, but there was a larger difference between quarter temperatures in the cows with moderate mastitis than in the cows with mild mastitis or the control cows. The hock-to-hock distance in the control cows was significantly smaller than in the cows with mild to moderate mastitis, but there was no significant difference in the distance either between the cows with mild mastitis and those with moderate mastitis, or between the cows with mastitis in the front quarters and those with mastitis in the hind quarters. The mechanical threshold to pain of the cows with mild and moderate mastitis was significantly lower than that of the control cows.