Winter conditions can lead to rapid dehydration and cracking of teat tissue, thus increasing mastitis risks. The purpose of this study was to evaluate the teat end health and skin conditioning performance of two experimental heptanoic acid based teat dips vs the commercial product Remain Gold ® using a split udder design during the winter season under best management winter milking practices. The experimental heptanoic acid teat dips KX-6185 and KX-6186 showed similar teat end health and teat skin conditioning to Remain Gold under winter conditions. Marked changes in teat end scores were measured over time and over periods as short as days. On the other hand, product treatment comparisons frequently showed parallel trends in score averages. This illustrates the importance of a split udder design to evaluate skin conditioning performance. The split udder design minimizes the risk of experimental bias due to cow and environmental factors. Most reported teat skin studies rely on comparing teat dips in separate cow groups with little consideration to group balancing even though factors such as hyperkeratosis is known to be affected by cow age and lactation stage. This study illustrates the high risk of traditional design skin toleration studies inaccurately attributing effects to teat dips.