Letter regarding “Peripheral and intestinal T lymphocyte subsets in dogs with chronic inflammatory enteropathy”

I am writing in response to the article “Peripheral and intestinal T lymphocyte subsets in dogs with chronic inflammatory enteropathy” published in Issue 3, Volume 38 of JVIM. It is stated by the authors that the Wilcoxon's signed rank test was used to compare quantitative and ordinal qualitative variables between the healthy control group and the chronic inflammatory enteropathy group. As these groups are independent, the assumption of paired samples required for the use of Wilcoxon's signed rank test is not met and the results reported are therefore invalid. I am wondering if the data could be re-analyzed using the Mann-Whitney U-test, which is the appropriate statistical test for non-parametric ratio and ordinal data.¹