Current literature contains references showing a connection between teat condition and udder-health variables. Unfortunately, for acute teat condition problems it is difficult to prove a causal chain as mastitis is dependent on a number of factors and causes. Even if the other influences on the teat condition could not be excluded within these field studies, which are predominantly represented in this article, it appears logical that the disturbance of the microcirculation has a negative influence on immune cell recruitment, decelerates teat canal closure and increases the amount of strip milk in the quarter after milking. Longitudinal studies are more significant than cross-sectional studies in terms of influencing variables and are therefore more reliable. Quarters of cows with teats classified as displaying severe hyperkeratosis have an increased risk of mastitis. These teats are more difficult to clean, promote colonization by bacteria and negatively influence the ability of the teat canal to close after milking. This paper attempts to describe the state of knowledge on the impact of a disturbed integrity of the teat canal mucosa, the teat tissue and the teat skin on the development of mastitis.