Teat End Problems and Their Likely Causes

Dr. Eleanor Jenson
USU Extension Veterinarian
Teat-end hyperkeratosis is a thickening of the skin that lines the teat canal and surrounds the external teat orifice. The condition is variously described as teat rings, teat flowers, teat erosion, callus formation, callosity, cornification or teat-end roughness.

Hyperkeratosis means “excessive keratin growth.” It is a normal physiological response to the forces applied to the teat skin during milking, either by a milking machine, a handmilker or a calf. The onset and severity of hyperkeratosis is profoundly influenced by the over-riding effects of climate, seasonal and environmental conditions, milking management, herd milk production level and genetics of individual cows. Reports of teat-end hyperkeratosis problems are far more prevalent in high-producing herds, for example, and especially during the colder periods of the year.

Cause of Hyperkeratosis

Major factors that can affect hyperkeratosis include teat-end shape, milk yield, peak milk flow rate, duration of milking and over-milking, stage of lactation, parity and the interaction between milking management and the milking machine. The total time per day when the milk flow rate is less than 1.0 kg/min appears to have a profound effect on the level of hyperkeratosis found.

In general, hyperkeratosis is more severe with long, pointed teats, slow milking cows and higher producing cows. Teat scores peak 3-4 months postpartum and decline as the lactation progresses.

The Australian Countdown Downunder Milk quality program produced a table linking risk factors for increased levels of hyperkeratosis with suggested reasons:

Risk Factor	Reason for Increased Likelihood of Teat-end Hyperkeratosis
Pointed Teats	The load applied by the closing liner acts on a smaller area of teat surface
Increasing age	The “wrinkle” factor in all species
Higher production	Cups are on for longer
Peak lactation	Cups are on for longer
Cups on before milk let down	Increased period of milk flow <1.0 kg/min (<2.2 lb/min)
Low threshold for ATOs	Increased period of milk flow <1.0 kg/min
Over-milking	Increased period of milk flow <1.0 kg/min
High vacuum	Increased stress on teat tissues

The huge variation in levels of hyperkeratosis between herds employing similar milking systems with comparable levels of yield suggests that there may be a considerable genetic influence which should not be overlooked.

Reducing Hyperkeratosis

Although some hyperkeratosis is an obvious and probably natural response to milking, there are steps which can be taken to reduce the condition. It should be noted there is also some natural resolution depending on stage of lactation.

There is evidence that the total period of time when milk flow is less than 1 kg/min can influence hyperkeratosis levels. This period includes the time before the onset of milk let down, as well as the more commonly recognized period of time after completion of milking. It is perfectly possible to over-milk a cow at the start of the milking session if she is poorly prepared.

Cows which are thoroughly prepared prior to cluster attachment exhibit improved milk let down, which leads to shorter and more complete milkings with a clearly defined end of milk flow. Advances have also been made in adjusting detachment flow rates for automatic takeoffs (ATOs).

Ensuring the teat skin is in good condition, maintaining skin moisture and natural elasticity, will help the teat to restrict the development of hyperkeratosis. Using a high quality teat disinfectant, carefully applied, is essential.

There is also a need for a close examination of the genetic effect on hyperkeratosis. In addition to the obvious link with teat length and shape, there would appear to be a more subtle effect, which may in part be related to the type of teat duct keratin and the ability of certain teats to retain keratin.

Hyperkeratosis in dairy cows is a multi-factorial problem. However, it is easily quantified and could be suggested as a measure to assess the quality of management on a dairy herd and the perspective the herd owner has on the welfare of the dairy cow.

Reprinted from NMC Annual Meeting Proceedings (2003), Mein et al., p. 114 and Ohnstad et al., p. 128