WE read with interest the short communication by Li and others (2011) on the renal function of dairy cows with subclinical ketosis. The authors claim that they have shown reduced renal function of dairy cows with subclinical ketosis. While we do not doubt that ketotic cattle may have reduced renal function, the data used by Li and others do not demonstrate this. First, to assess this claim we need to be able to confirm that the two groups are equivalent. Li and others (2011) report data from 55 normal and 55 subclinical cows. As the latter could not be detected before sampling, the 55 normal cows …