Deterioration of teat skin quality can adversely affect milk quality. Trauma and lesions can be caused by a number of factors: machine milking effects, environmental effects and/or agents and finally, infectious agents. Diagnosis of lesions is important in assessing appropriate management practices.
J. Eric Hillerton, G.A.Mein, F.Neijenhuis, W.F.Morgan, D.J.Reinemann, J.R.Baines,
I.Ohnstad, M.D.Rasmussen, L.Timms, J.S.Britt, R.Farnsworth, N. Cook & T. Hemling,
The various types of abnormal condition of teats of dairy cows caused or affected by environmental factors are described. This paper is part of a series of six publications covering all aspects of unsatisfactory teat conditions, their impact, causes, evaluation and treatment.
Various agents and mechanisms, causing a number of forms of trauma or lesions, may affect the condition of the teats of the milking dairy cow. In general, these agents and mechanisms fall into one of three broad categories:
- Machine milking effects
- Environmental effects and/or agents
- Infectious agents
Table 1 Teat conditions observable according to the cause of the problem.
||Other abrasions and cuts
||Foot and Mouth Disease
|Hemorrhaging – petechia
|Hemorrhaging – larger
Short-term effects and medium-term changes caused by machine milking have been described previously (3), similarly for the more chronic changes known as hyperkeratosis (4).
A second group of skin conditions is caused by infections and again they have been described (2).
Any teat skin condition less than perfect may indicate the standard of the hygienic practices, as well as mastitis prevention and milk quality management employed on the farm, and may be used to indicate exposure to environmental conditions injurious to cow welfare. Any deterioration of teat skin condition may adversely influence milk quality, milk safety, and udder health and present hazards to the health and safety of staff.
Here, commonly encountered conditions, induced by a variety of environmental factors affecting teat skin are considered. These may be related primarily to weather, sunburn or frostbite. They may be directly caused damage such as cuts, abrasions or damage from insect bites and occasionally calf suckling or suckling by herd mates. Some conditions have multifactorial causes including allergic reactions or chapping of skin. Chemical damage may occur due to accidental use of inappropriate products, especially for teat hygiene.
Appreciation of the different skin conditions and differential diagnosis will be aided by use of the Teat Club International portfolio of teats available on compact disc. Appropriate techniques and methods to compare teat condition between herds and within a herd over time have been recommended (3, 5). This includes the number of teats and cows to be examined and how to estimate the severity and significance of the observations.
On examination of teats many conditions may be observed. The most frequent variation of the teat from perfect condition is the degree of roughness of teat skin. This is the simplest of a series of environmentally related conditions that are usually unconnected to the action of the milking machine but may be causally related to the milking process.
The appearance of skin roughness varies with the color of the teat. As roughness is accompanied by, or due to dryness, then black teats always look rougher. A simpler guide is to draw a finger down and around the teat and to feel the amount of friction. This is best achieved when wearing thin surgical rubber gloves. (These should always be worn in the interests of hygiene). At a practical level only three grades of roughness are needed.
The smooth teat is one where there is no apparent drag on the finger and the teat looks shiny, but is not edematous. A rough teat will have noticeable drag. A very rough teat gives significant drag on the rubber to the extent of puckering it. This teat will usually have dry skin flaking from the surface.
Roughness is the only teat condition that should be assessed before milking. The slightly wet teat after milking will often look shiny and feel smooth. The extent of roughness may then have to be observed on the area above the top of the liner, which is unsatisfactory in many instances.
Teat chaps present as horizontal cracks, open or scabbed, following the natural transverse folds of the shrunken teat. They may occur more obviously on the anterior surfaces of front teats and the posterior surfaces of hind teats. The effects of a poor climatic environment on abraded teat skin induce chaps. Usually this is excessive drying of wet teats often caused by cold draughts and winds. Poor housing or pasture may mean that mud abrades the teat and is a primary problem. Strip grazing of brassicas (kale) in autumn/winter is a well-reported risk factor although this may involve irritancy too. Poor liners and over aggressive teat cup removal may also cause primary trauma leading to chapping.
Often the occurrence of chaps indicates poor application of teat disinfection or use of an inappropriate product. It is essential to use a high emollient concentration, always more than 5% glycerol or equivalent. Treatment of chaps benefits from smearing the affected areas with glycerol alone then dipping (not spraying) with an appropriate product. It is crucial that the whole teat surface is covered with disinfectant. Excessive emollient should not be added to proprietary teat disinfectants, as this will impair bactericidal activity. Good disinfectant activity is necessary to prevent secondary infections.
During the development of teat disinfection it was shown clearly that preventing and curing teat chaps was essential in reduction of mastitis caused by contagious pathogens.
Contamination by soil occurs as a general splashing of mud on to the teats and udder and when cows lie on bare soil. The former is often a problem of a high density of traffic through a gateway. The latter may occur in sand bedded systems or when cows ‘camp’ on bare soil areas e.g. under shade in late summer. Then the soil may also be heavily contaminated with feces. Problems only really occur when there is poor washing and either milking or walking ‘sands’ the skin. The condition presents as a raw area; telltale mud and sand will be obvious.
Suckling by other animals, often newly calved heifers, of herd mates is not uncommon. Damage is more commonly observed on the newly calved animal at the first milking. Then the damage is caused by the dam’s own calf.
The lesions resulting are similar to chaps but are vertical on the teat and not transverse. They are usually caused by teeth scraping the skin. Treatment is the same as for chapping but, in addition, the cross-suckler must be identified if a herd-mate.
Insects may damage teats in several ways. Biting species, including stomoxinae, culicoides midges, sand flies and mosquitoes may suck blood and leave puncture wounds. It is these wounds that are enlarged by the rasping mouthparts of muscids such as the head fly, Hydrotaea irritans. This is considered to be the mechanism of transmission of ‘summer mastitis’ in northwestern Europe.
Other species may create larger, discrete wounds. These include the excision of tissue by the yellow-jacket wasp as reported from Israel. Various ticks may be found on teats but relatively infrequently, as improved pastures are a poor environment due to their frequent disruption. The initial bite may cause a problem especially by disruption in the parlor. More frequently it is reaction to the bite and secondary infections, both viral and bacterial that cause most problems.
Abrasions and cuts
Any abrasions that occur are usually related to lying conditions and muddy/sandy soils. Very old liners may also cause limited abrasions. Cuts to teats are usually caused by hooves when cows are rising or lying down, often because the stalls are of incorrect size or hoof management is poor. At pasture they are more likely to be caused by wire fencing.
Usually cuts require treatment, often suturing. Failure to treat in the milking cow may be a problem as milking often reopens the wound leading to blood in the milk. Also a poor heal may leave a flap of tissue that affects liner action. Suturing may be avoided by use of medical tapes that can be applied to clean skin.
Often, if a cut is near the orifice, then a cannula is inserted into the teat duct. This should be avoided if at all possible, as these are a major risk factor for intra- mammary infection.
At least three types of weather conditions affect teat skin. Cold winds on wet teats cause chaps. Sun and frost cause direct effects. Frostbite is not uncommon in very cold areas even in a dry cold. The likelihood of frozen teats depends both on the air temperature and on the wind speed. Teats start to freeze in a wind of 60 km/h (40 mph) just below freezing point, at –10° C (14°F) freezing starts in a wind of 15 km/h (10 mph) and teats will freeze in still air at –18° C (-1°F). Frostbite may more usually affect front teats and distally. Teats may initially appear reddened or pale. When severe, a scab forms that eventually drops off to leave a raw teat end. The teat duct must not be allowed to become occluded.
Sunburn affects pink teats and is less likely in pigmented teats and so some breeds rarely suffer. It is also most likely on easily exposed teat skin and so will be directional and not affect the whole circumference of the teat. Thus, it may affect the outside of teats on one side of the udder and the inside of the teats on the other side of the udder. This occurs because the effect is greatest when cows lie down and any one cow usually only lies on one side. Teats are shaded during the greatest exposure of ultraviolet B light when the cow stands.
When severe blistering occurs it must not be confused with vesicles from viral infections. Sunburn may occur in any geographical area, as it is not necessarily related to temperature but only to ultraviolet light. Climatic change is predicted to increase ultraviolet light and so the relative risk may increase. At least one company sells a sun block specifically for teats.
Sun may also contribute to photosensitization of teat skin. This is a product of interaction of sunlight and phytotoxins or other environmental chemicals or drugs. Hypothetically, there may be many possible occurrences but specific examples are few and rare. Phytotoxins may come from plants in the grazing or be systemically distributed from foodstuffs.
St John’s Wort causes primary photosensitization. Bermuda grass may be a primary irritant whose effects are exacerbated by sunlight. Ragwort disrupts liver function and has secondary effects often on the mammary gland making it more sensitive to light.
Unpigmented areas of teat skin develop an erythema and occasional edema often results. Eventually the skin becomes cracked, possibly necrotic and will be shed. Because the toxin is usually distributed systemically over white areas of skin, particularly bare skin, not only the teats will often be affected.
Cows spending a long time in cooling ponds often show erythema extending over the whole of the lower body up to a ‘tide mark’ that includes the teats and udder.
Teat damage resulting from chemicals is usually the result of a defective teat disinfectant product or the application of a wholly unsuitable material.
Any teat disinfectant may cause a problem if formulated wrongly. Correct concentration may not be prepared, freezing may separate components, or the water supply may be contaminated. Teats appear dry and roughened, often pink teats are reddened, especially distally. When an iodophor is used the teat may be heavily stained. The effects are rarely acute although high concentrations may induce hyperplasmia and a very leathery appearance to the teat. All teats will be affected. Changing to an appropriate product will result in a rapid resolution. Iodophors cause allergies in milkers but claims of this occurring in cows have yet to be substantiated.
The mistaken use of a concentrated washing product e.g. a tank cleaner will cause severe damage to teat skin, as these are usually highly corrosive products. Resolution is much slower and a severe outbreak of clinical mastitis is likely. The more deleterious the product used then the more teats will be affected in number and severity, and the more rapidly the effects will occur.
Problems may also occur when slaked lime is used as a drying agent in bedding. The effect may be directly on the skin or more significantly when a hypochlorite teat dip is used.
Aldehyde products used as a disinfectant on bedding or in a footbath may also cause chemical burns. In bedding the effects will be laterally on the teats and skin of the lower body. Splashing from a footbath will cause discrete localized areas of damage but spread over the posterior distal body with the coronary band often significantly reddened.
Scoring reactions and responses
When assessing teat condition, all lesions observed should be recorded. Few lesions and no infections should be found if good husbandry is being applied. Indeed identification of any lesions should be rare in routine teat condition monitoring in developed dairy industries. It is more likely that problems will be encountered when investigating problem herds with either poor milking performance, a mastitis problem or a reported teat condition problem of any form.
The occurrence of any impaired teat condition and the importance of making a correct identification should never be underestimated. A specific diagnosis is essential to indicate the strategic significance of the problem, to identify the risk for the rest of the herd and the farm staff, and to design a treatment program to alleviate the condition and remove the causes. When lesions appear severe or affect more than a few teats then remedial action is necessary. First there must be removal or control of the causative agents. Then specific treatments may be required, some are suggested above. More details on treatments are given in a companion paper (1). Often salves or ointments may be recommended.
Frequent practical experience is that usual farm practices rarely keeps these products clean and sterile after initial use, and that subsequent treatment is a major risk to secondary infection of any teat wounds.
- T. Hemling, G.A.Mein, F.Neijenhuis, W.F.Morgan, D.J.Reinemann, J.E.Hillerton, J.R.Baines, I.Ohnstad, M.D.Rasmussen, L.Timms, J.S.Britt, R.Farnsworth & N.Cook (2002) Evaluation of bovine teat condition in commercial dairy herds: 6. Teat condition - prevention and cure through teat dips. These proceedings.
- J.E.Hillerton, W.F. Morgan, R. Farnsworth, F. Neijenhuis, J.R. Baines, G.A. Mein, I.Ohnstad, D.J. Reinemann & L. Timms (2001) Evaluation of bovine teat condition in commercial dairy herds: 2. Infectious factors and infections. Proceedings of the 2nd International Symposium on Mastitis and Milk Quality, NMC/AABP, Vancouver, p352-356.
- G.A.Mein, F.Neijenhuis, W.F.Morgan, D.J.Reinemann, J.E.Hillerton, J.R.Baines, I.Ohnstad, M.D.Rasmussen, L.Timms, J.S.Britt, R.Farnsworth, N.Cook & T. Hemling (2001) Evaluation of bovine teat condition in commercial dairy herds: 1. Non- infectious factors. Proceedings of the 2 nd International Symposium on Mastitis and Milk Quality, NMC/AABP, Vancouver, p374-351.
- F.Neijenhuis, G.A.Mein, J.S.Britt, D.J. Reinemann, J.E.Hillerton, R.Farnsworth, J.R.Baines, T.Hemling, I.Ohnstad, N.Cook, W.F.Morgan & L.Timms (2001) Evaluation of bovine teat condition in commercial dairy herds: 4. Relationship between teat-end callosity or hyperkeratosis and mastitis. Proceedings of the 2nd International Symposium on Mastitis and Milk Quality, NMC/AABP, Vancouver, p362-366.
- D.J. Reinemann, M.D. Rasmussen, S. LeMire, F. Neijenhuis, G.A.Mein, J.E. Hillerton, W.F. Morgan, L.Timms, N.Cook, R.Farnsworth, J.R.Baines & T.Hemling (2001) Evaluation of bovine teat condition in commercial dairy herds: 3. Getting the numbers right. Proceedings of the 2 nd International Symposium on Mastitis and Milk Quality, NMC/AABP, Vancouver, p357-361.