week THREE: Evaluation of Bovine Teat Condition in Commercial Dairy Herds

October 31, 2012 in Weekly Series: A Tool Box for Udder Health

week THREE: Evaluation of Bovine Teat Condition in Commercial Dairy Herds: 1. Non-Infectious Factors

Ohnstad4, M.D.Rasmussen2, L.Timms5, J.S.Britt5, R.Farnsworth5, N. Cook5 & T. Hemling5.
“Teat Club International”, c/o F. Neijenhuis, Research Institute for Animal Husbandry
Lelystad, The Netherlands. email: f.neijenhuis@pv.agro.nl
Co-authors from: Australia1, Denmark2, The Netherlands3, UK4, USA5

ABSTRACT
Classification of bovine teat condition can be used to assess the effects of milking management,
milking equipment or environment on teat tissue and the risk of new intramammary infections.
Veterinarians and others require a simple and reliable method for evaluating teat health in dairy
herds. A protocol for systematic evaluation of teat condition in commercial herds is proposed.
Guidelines for interpretation of observations are given. The relative influence of non-infectious
factors affecting short-, medium- or longer-term changes in teat condition are reviewed briefly
and discussed. The main short-term (single milking) effects include changes in color, swelling
and firmness of the teat-end and barrel, and the degree of openness of the external teat orifice.
The main medium-term effects (requiring a few days or weeks) include changes in teat skin
condition and incidence of petechial haemorrhages. Changes in teat-end hyperkeratosis appear
to be longer-term effects (typically 2-8 weeks) in the absence of unusually harsh weather
conditions. Very long-term effects (typically occurring over a few or many months) such as
changes in size, tissue fibrosis and thickness of teats, are not discussed in this paper.

INTRODUCTION
Maintenance of healthy teat skin and teat-ends is a key part of any effective mastitis program.
Changes to teat tissue, particularly the skin of the barrel, teat-end, and teat canal, alter the risk of
new mastitis infections (7,11,26), sub-clinical mastitis inferred from CMT scores (19) or clinical
mastitis (30). Instruments and measurement techniques used to assess the condition of teat tissue
include changes in teat thickness with a modified cutimeter, ultrasonography, sub-cutaneous
oxygen tension (8,11,12), and pulse oximetry (21). These techniques vary in practicality in the
field, the expertise and cost required to use them, and in their demonstrated repeatability and
precision. Simpler methods for quantifying the short- or medium-term effects of milking on
teats were proposed by Hillerton et al. (14,15) who noted that many effects of machine milking
are easily recognisable immediately after cluster removal.

Numerous classification systems for teat-ends and skin condition have been published (for
example: 2, 25, 27, 38, 41, 43, 44). Visual assessment of teats, comparison with photographs,
and scoring schemes in nominal categories are the most common methods. In addition, many
veterinarians and advisers have devised their own unique classification systems. Simpler
methods that reduce time and effort for the evaluator, and also minimize interference with
milking routines, would increase their utility for assessing teats in commercial dairy herds.

The purposes of this paper, by an informal discussion group of researchers and udder health
advisers self-styled as the “Teat Club International”, are:

1) to review non-infectious factors affecting short- or medium-term changes in teats;
2) to propose a simple protocol for systematic evaluation of teats in commercial dairies;
3) to propose guidelines for interpretation of these observations.

The full version of this paper with many references, example pictures and sample recording
charts is posted on the UW-Madison Milk Quality website (http://www.uwex.edu/milkquality/ ).
Other companion papers in the “Teat Club” series in this AABP/NMC Conference Proceedings
discuss infectious factors (13), data collection and analysis (39), and the relationship between
teat-end hyperkeratosis and mastitis (31).

Short-Term Changes In Teat Condition (Responses To A Single Milking)
Faults in milking machines or milking management are the primary cause of short-term changes
in color, firmness, thickness or swelling of teats, or degree of “openness” of the teat orifice.

Color changes
Some teats are noticeably red, either at the teat-end or over the entire teat, when the cluster is
removed. Others may become reddened within 30-60 s of cluster removal. In extreme cases,
teats become blue or already appear blue when the cluster is removed, indicating cyanosis (14,
15). See examples 1-3 in the attached Powerpoint “Teat Slides” file (from 15).

Poor teat color after milking may be worse for short or slender teats (37). Color changes are
exacerbated by overmilking (14), especially with wide-bore liners (16) or tapered liners with
wide upper barrels, unusually heavy cluster weight (15), high milking vacuum (36), faulty
pulsation (17, 22, 40), or mismatch between type of liner used and mean teat size within a herd.
Black teats must be excluded from any color-based evaluation. Changes can be classified
according to the proportion of light-colored teats that, when examined within 1 min of cluster
removal, are:

1) Normal (pink)
2) Reddened (part of or all the teat-end or barrel may be discolored)
3) Blue-colored (part of or all the teat surface appears to be tinged with blue or purple).

Because the causes of reddened or bluish teats may differ, red and blue classes should be
recorded separately. However, a further simplification is to combine the red and blue categories
into a single category for analysis of Normal (pink) versus Discolored (red or blue-colored).

Swelling at or near the teat base
When examined after milking, the upper part of the teat may have a visible line or mark caused
by contact with the liner mouthpiece lip. Alternatively or in addition, there may be visible
swelling (with a palpable, thickened ring) in the unsupported area that was inside the liner
mouthpiece chamber near the end of milking (14). See examples 4 and 5 in the attached
Powerpoint “Teat Slides” file. To avoid confusion with physiological swelling of teats and
udders, cows with obvious signs of udder edema, or cows that calved within 1 week of teat
evaluation, should be excluded.

Factors commonly responsible for swelling around the top of the teat as a direct result of milking
include: high mouthpiece vacuum associated with wide-bore liners (32); overmilking, especially
with wide-bore liners or tapered liners with wide upper barrels (16); teatcup crawling; or liner
mouthpiece lips that are unusually stiff or narrow in relation to teat size.
These effects can be evaluated according to the proportion of teats that, when examined within 1
min of cluster removal, are:

1) Normal (no ring, little or no swelling)
2) Visible mouthpiece lip mark or “garter mark”
3) Marked swelling or palpable thickened ring.

To simplify data analysis, the “Normal” and “Visible lip mark” classes were combined into a
single category by Hillerton et al. (15) even though they were recorded separately. Pooling data
into two categories, Normal (no or mild swelling or lip marks) or Swollen (marked swelling or
thickening) is recommended to simplify the evaluation and statistical analysis.

Hardness at or near the teat-end
Many teats feel soft and compliant after milking and they contract when touched. However,
some teats feel swollen or firm or, in extreme cases, hard and unresponsive to touch (15). Teats
often look flat or “wedge-shaped” after milking. “Wedging” describes the (typically slight)
flattened shape of the teat-end due to the compressive load applied by the opposing walls of a
collapsed liner. Severe wedging which induces a reduction in teat end volume may result from
hard liners, liners mounted under high tension, a prolonged D-phase or failure of the liners to
open fully (Hillerton, Ohnstad, personal communications).

Factors commonly responsible for swelling near the teat-end include overmilking (8), use of
wide-bore liners (14) or liners with high mouthpiece chamber (36), high vacuum (4,10),
pulsation failure (24), insufficient rest phase of pulsation (9) or short A- and C-phases of
pulsation (29).

Teat-ends can be classified by simple visual examination supported by manual palpation, as:

1) Normal (soft and supple)
2) Firm, swollen or hard, or severely wedged.

Openness of the teat orifice
When examined immediately after milking, the external teat orifice may appear to be closed,
slightly open or, in extreme cases, with a funnel-shaped opening about the size of a match-head.
See example slide 6 in the attached Powerpoint “Teat Slides” file (from 15). According to
independent unpublished observations by three co-authors, both the new infection rate and the
proportion of teats with open teat orifices were reduced in several mastitis problem herds in
Australia, UK and USA following changes to milking equipment or procedures. In most of these
anecdotal reports, a change in liner type was thought to be the single largest contributory factor
in solving the mastitis problem (unpublished field data: Mein, Morgan, Ohnstad).

Factors linked with short-term, post-milking openness of the teat orifice include high milking
vacuum (4), overmilking, design of liner mouthpiece, unusually heavy cluster weight (15), or
high liner mounting tension (3).

Teat orifices can be classified, by qualitative assessment within 1 min of cluster removal, as:

1) Closed
2) Open (more than 2mm wide or deep).

A clean paper towel can be used to remove milk residue from the teat end. When estimating the
degree of openness, it is helpful to compare the width or depth of an open orifice with a common
object such as a match-head (about 3mm in diameter) or the shaft of the match (about 2mm).

Medium-Term Changes In Teat Condition (Responses Visible Within A Few Days Or Weeks)
Machine-induced changes in the incidence of petechial haemorrhages or larger haemorrhaging
may occur immediately or may take several days before becoming evident. Changes in teat skin
condition associated with harsh weather or chemical irritation may take a few days or weeks.

Teat skin condition
Healthy teat skin is coated with a protective mantel of fatty acids that are derived from the
dermal layer and which retard the growth of bacterial pathogens (5). When exposed to cold, wet
and windy conditions, the skin of machine-milked teats often becomes scaly, irritated or chapped
(broken skin) and the protective surface coating may be removed, thereby allowing colonization
of pathogens such as Staphylococcus aureus (5, 33). Cold, wet or muddy conditions induce
hardening or thickening of teat skin. Mud, as it dries, draws moisture from the skin with a
consequent loss of elasticity of the teat skin. Machine milking exacerbates problems of chapping
or cracking. Chemical irritation associated with disinfectant type or concentration, or
inappropriate type or concentration of emollients, may exacerbate the effects of harsh weather
conditions and promote teat chapping. Skin conditioners or emollients either reduce evaporation
from the skin or act as humectants to maintain or improve the teat skin condition (38). The
dryness of black teats tends to be over-estimated by observation alone. Evaluation is improved
by lightly rubbing the teat skin with a finger. In the absence of cracks and sores, differences in
skin condition classed as smooth or rough do not seem to influence new mastitis infection rates
(38). Consequently, we propose the following simple classification system:

1) Normal (smooth sheen, soft, healthy skin)
2) Dry (scaly, flaky or rough skin but with no cracking).
3) Open lesions (allow space for specific description, eg., chapped, cracked, blackspot).

Vascular damage
The proportion of teats with petechial haemorrhages, or more extensive haemorrhaging, is one
indication of the extent of any vascular damage. Vascular damage usually reflects some type of
pulsation failure (22, 24), often associated with high vacuum and/or prolonged over-milking.
Incidence is lower in herds milked with narrow-bore liners, at low vacuum, and/or with
automatic detachers. See example slide 7 in the attached Powerpoint “Teat Slides” file.

Longer-Term Changes In Teat-End Condition
The degree of teat-end hyperkeratosis (roughness, cornification or callosity) is a dynamic
condition. Status of teat-ends for an individual cow or herd can change within days, especially in
regions subject to harsh weather conditions or sudden weather changes (44). Seasonal conditions
may affect dryness and hardness of keratin (2, 44). In the absence of unusually harsh weather
conditions, however, changes in teat-end status occur over a period of 2-8 weeks.

Apart from seasonal weather conditions, major factors affecting teat-end hyperkeratosis include
teat-end shape, production level and stage of lactation, and interactions between milking
management and machine factors (especially slow milking and over-milking). According to
some experienced observers, the genetic predisposition of individual cows appears to influence
the degree of hyperkeratosis. This genetic influence is in addition to the more obvious effects of
teat size and shape (Hillerton, Timms, personal communications). In general, teat-end scores are
poorer for long pointed teats (1, 27), slow milking cows or higher-producing cows (23, 27,42).

Teat scores change with stage of lactation and parity. Teat-end hyperkeratosis may be
exacerbated by disinfectants that cause chemical irritation to teat skin or may be improved by the
use of a disinfectant with a high concentration of an effective emollient.

Of the milking management or machine factors, the total time per day when milk flow rate is less
than about 1 kg/min appears to have a major effect on teat-end condition. Teat-end roughness is
influenced by pre-milking udder preparation, timing of cups-on and by threshold settings for
automatic cluster removal (35). These effects are exacerbated by high vacuum (16, 18), overmilking
(34), use of liners with stiff mouthpieces or liners that are mounted at high tension (3).

The association between teat-end hyperkeratosis and mastitis is discussed in a companion paper
(31). Those results provide the framework for our proposed international system for classifying
teat-ends as follows.

1) For research studies, use the scoring method developed by Neijenhuis et al. (28).
2) For routine field evaluation, use the following simplified system.

-No ring (N) – a typical status for many teats soon after the start of lactation. This category
includes teat-ends scored as HK0 in the UK or N in NL, and some teats scored as 1 in US.
-Smooth or Slightly rough ring (S) – a raised ring with no roughness or only mild roughness
and no keratin fronds. This category includes teats classified as HK0 or 1 in UK, as 1A, 1B
or 2A in NL, 1 in AU, and most teats scored as 2 in the US.
-Rough (R) – a raised roughened ring with isolated fronds of old keratin extending 1-3 mm
from the orifice. This category indicates some breakdown in epithelial integrity. It includes
teat-ends classed as HK2 or 3 in UK, 2B or 2C in NL, 2 in AU, or 3 in the US.
-Very Rough (VR) – a raised ring with rough fronds of old keratin extending >4 mm from
the orifice. The rim of the ring is rough and cracked giving the teat-end a “flowered”
appearance. This category includes teat-ends classified as HK4 or 5 in UK, 2D in NL, 3 in
AU, or 4 in US.

Examining Teats And Interpreting Results

• To simplify and streamline the procedure, teat condition should be evaluated immediately
after the cluster is removed and before application of a teat disinfectant. However, if an
observer wants or needs to assess skin changes in greater detail (see, for example, ref. 6), it
will be necessary to evaluate teat skin condition just before milking.
• Exercise great care when approaching cows and handling teats – especially in herds where
cows are not used to having their teats touched.
• Observe and record teats in a regular pattern.
• View the teats, initially, without handling.
• Dry the teat-end with a paper towel if milk residue or debris obscures the view of the orifice.
• View teats by gently grasping the teat above the teat-end. Observe the teat from side on and
then from end on. Good lighting is essential. If lighting is poor, use a headlamp rather than a
flashlight for hands-free evaluation. This is important for increased work safety.
• Score all teats of all cows in herds of up to 80 cows, or a random sample of at least 80 cows
in herds with 80 – 400 cows, or at least 20% of cows in herds larger than 400 cows (see
companion paper by Reinemann et al, 2001). To ensure confidence in the data, score a
representative sample of cows from all feed groups and management groups.
• An automatic recording method, such as a dictaphone, enables a single observer to evaluate
and record teats. If two people are present, one can observe teats while the other records data.

How many cows?
Perhaps the most common weakness of teat evaluation procedures in commercial herds is that
sample sizes are too small. Preliminary guidelines for the collection of statistically defensible
data were published by LeMire et al. (20). One method for assessing and describing the teat
condition status of a herd of cows is to measure the proportion of teats that have a particular
condition classed as abnormal, eg., more than 20% of teats with rough teat-ends, or more than
20% of light-colored teats classed as reddened or blue-colored after milking. These and other
statistical issues, such as the influence of herd size, are discussed in our companion paper (39).
Further investigations may be required if one or more of the following are observed:
Main short-term and medium-term effects (primarily associated with milking machine faults or
poor milking management resulting in long periods of flow below 1 kg/min and/or overmilking)

-Color: more than 20% of cows with light-colored teats have one or more teats that are visibly
reddened (congested) or tinged with blue (cyanotic).
-Swelling at or near the top of the teat: more than 20% of cows have one or more teats with
marked swelling or palpable rings.
-Swelling and hardness at or near the teat-end: more than 20% of cows have one or more
teats-ends classified as firm, hard or swollen, or severely wedged.
-Openness of teat orifice: more than 20% of cows have 1 or more teat orifices classed as open.
-Vascular damage: more than 10% of cows have petechiations on one or more light-coloured
teats.

Main medium-term and longer-term effects (primarily associated with poor environment,
management or chemical irritation, or cow factors such as teat shape, yield and genetics. These
effects are exacerbated by machine milking, especially if poor milking management results in
overmilking or prolonged milking at low milk flow rate. Faults in milking equipment are
unlikely to be the primary causal factors if one or more of the short-term changes, as listed
above, are not obvious)

-Teat skin condition: more than 5% of cows have open lesions (including chaps or cracks) on
one or more teats.
-Teat-end hyperkeratosis: more than 20% of cows have one or more teats that are scored R or
VR, or more than 10% that are scored VR.

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