Post-milking teat disinfection, is there still something interesting to write about this topic? It has been widely covered since it has been proven to reduce the incidence of new intramammary infections. Although the state-of-the-art is well-known, we are often surprised by how this step is performed daily on the farm. This article will underline the importance of teat disinfection after milking. The worldwide regulatory positioning will give us some insights on how a teat dip is evaluated during the registration process. We’ll have a close look at the EU biocide directive, the main active substances, and other ingredients such as emollients and film forming agents that can be found in the teat dip/spray formulations in order to prevent mastitis. Finally, because post-milking teat disinfection is not effective if not properly applied on the teats, the principles of a correct application will be reviewed.
In this review, the terms teat dip/teat dip solution/post-milking teat dip (PMTD) or teat disinfectant products will be used equally as general terms to describe solutions applied on the teats after milking.
Teat dip history
One of the cornerstones of the mastitis 5-point plan
Teat dip is one of the cornerstones of the 5-point plan set up in the 1960s by the National Institute for Research in Dairying (NORD) in the UK.
The five principles are the following (1):
- Record and treat clinical cases of mastitis
- Apply a blanket dry cow therapy
- Get rid of chronically infected animals
- Regularly maintain the milking equipment
- Disinfect the teats after milking
With these principles, the incidence of bot clinical and subclinical mastitis has drastically decreased. Bradley (2002) (2) reports a dramatic decrease in both the overall incidence of clinical mastitis (from over 150 to 40 cases per 100 cows per year) and the incidence of contagious pathogens between 1967 and 1982. The average bulk milk somatic cell count in England and Wales decreased from 600,000 to just over 400,000 cells/ml. Communication, education and legislation have modified the practices in the milking parlour.
In the “NMC updates Post-milking teat disinfection fact sheet”, the National Mastitis Council answers the question: Why is post-milking teat disinfection so important? “The rate of new intramammary infections can be reduced 70 percent or more by disinfecting all teats of all cows with an effective product immediately after every milking, compared with no disinfection. Teat disinfection does not affect existing mammary gland infections, but it may reduce colonization of the teat end by mastitis pathogens and thus reduce the chance of new intramammary infections.” (3).
Focus on disinfection… and skin compatibility
Historically, as described in the 5-point plan, the expectation of a teat dip solution is to disinfect the skin. However, as we will see later on in this paper, not only disinfecting properties are important. The skin compatibility as well as the coverage effect are also contributing to the role of a teat dip or spray solution in mastitis prevention.
As the disinfectant impacts the skin lipidic film, the best product is not always the one with the highest concentration of disinfectant. There must be an adequacy between the farm circumstances and the chosen solution.
Let’s have a look at the teat dip formulation and the regulatory positioning.
How to evaluate teat dip efficacy and regulatory positioning
How to evaluate disinfecting activity of a teat dip?
An in vivo field trial means that the performance of some new product is tested under the conditions in which it will be used. In vivo trials include experimental challenges and natural exposure designs. As concluded by Fitzpatrick et al. (2018) (4) in the review of test protocols for the evaluation of teat disinfectants, experimental challenges must be carried out in research farms and are not representative for the circumstances in commercial farms. Although requiring longer and more expensive studies, natural exposure field trial give a better indication of what can be expected of the teat disinfectant within a commercial farm environment. The article also suggested to conduct an evaluation study in two different herds: one having a high prevalence of contagious mastitis causing pathogens, and the other one having a high prevalence of environmental mastitis causing pathogens. This way, a sufficient number of new intramammary infections can be established to determine the disinfecting activity.
In vitro trials include the excised teat protocol and the agar diffusion assay. Over the past decades, the excised teat protocol has been less promoted to evaluate the effectiveness of a teat dip. It has been mainly used as an initial phase of development to screen different active substances regarding their germicidal activities. Agar diffusion assay (Kirby Bauer method) is presented by Fitzpatrick et al. (2018) (4) as a potential in vitro method to assess the teat disinfection properties.
Schwenker et al. (2022) (5) have also used Minimum Inhibitory Concentrations of chlorhexidine and lactic acid-based teat disinfectants to assess the bacterial selection and susceptibility. MIC values are difficult to extrapolate into practical application, as several factors have an impact on the efficacy in the field including the difference of surface on which the teat disinfectant is applied, and the presence of organic matter as well as of milk residues.
Legal requirements mandatory to release a teat dip on the market
The regulatory positioning of the product varies worldwide and has changed over the past decades. A medicine is something that treats, prevents or alleviates the symptoms of disease. Therefore, in some countries, teat dips have been included in the medicinal product category thanks to their role in mastitis prevention.
This is for instance the case in China and in some South American countries. In Canada as well, teat disinfection products must complete a full submission and approval process for veterinary drugs.
In Europe, some teat dips are registered as medicinal teat dips. Safety, toxicity and efficacity studies are required for the registration process. Only a few manufacturers have chosen this registration path to bring their product to the market.
In the United States, teat dips are considered a drug and are submitted to FDA listing. The definition given in the CPG Sec. 654.200 Teat Dips and Udder Washes for Dairy Cows and Goats is the following: “Teat dips are drugs that are applied to the teats of lactating animals immediately following milking and removal of the milking machine to control the spread of mastitis. Since the control of mastitis is inherent in the purpose for using teat dips, the control of mastitis constitutes their intended use whether or not specifically labelled for this purpose.” Today they may currently be marketed as over-the-counter drugs and without NADA approval (6).
As a borderline positioning between medicinal product and antiseptic solution, Europe has now regulated the status of the teat dips in the Biocidal Products Regulation (BPR). A biocide is an active chemical used to inhibit or destroy germs, usually on hard surfaces [definition from the European Chemicals Agency (ECHA)].
What about products with no claim or no test reference?
Teat dips must go through different registration and validation steps before they can become available on the market. The number of registration and validation steps depends on the legal requirements during the registration process. A product that has not been registered do not give any guarantee. It is highly recommended to ask test data and licenses to the manufacturer or supplier.
Biocidal product Regulation, assessment, and evaluation of efficacy
Biocidal products are ruled by The Biocidal Products Regulation (BPR). The first text was the 98/8/EC Directive. Now the (EU) 528/2012 Regulation is in force. It aims to harmonize the market at Union level, while ensuring protection for humans and the environment. The Guidance on the Biocidal Products Regulation, volume II : Efficacy describes the conditions that need to be fulfilled before biocides can become available on the market.
A biocidal product must be authorised before being sold in EU countries. There are three types of authorisations:
- Simplified authorisations, when the biocide has a favourable environmental or human and animal health profile, it can be a simpler procedure,
- Union authorisations are authorisations granted by the entire EU/EEA and Switzerland,
- National authorisations: the marketing authorization holder submit an application in a chosen EU Member State. A mutual recognition procedure is possible, either in sequence or in parallel. The company wishing to sell in other EU markets is asking other Member States to recognize the national production authorization.
The analysis is made according to the active substance. First, the active substance is evaluated and approved for a specified product-type. Twenty-two product-types are defined in four main groups. The main groups are: disinfectants, preservatives, pest control and other biocides. The first main group of disinfectants contains five product-types, amongst them the product-type 3: veterinary hygiene. It is described as products “used for veterinary hygiene purposes such as disinfectants, disinfecting soaps, oral or corporal hygiene products or with anti-microbial function”, and also “used to disinfect the materials and surfaces associated with the housing or transportation of animals”.
Surface disinfectant for animal housing, hoof disinfection solutions and teat dips, are belonging to this category. Table 1 presents the 22 different Product-Types described in the Biocidal Product Regulation guidance.
Under a Product-type (PT), specific categories with specific lab testing conditions have been described for different usages. In the case of post-milking teat disinfection, two types of tests are part of the basic requirements:
- a quantitative suspension test (phase 2, step 1);
- a quantitative carrier test (phase 2, step 2), or a field test
all simulating practical conditions appropriate to its intended use (temperature, soiling, different surfaces, contact time, etc.).
The Phase 2, step 1 is described in detail. The reference norm for bactericidal activity is the EN1656 with 3 bacteria: Escherichia coli, Streptococcus uberis and Staphylococcus aureus. The reference norm for yeasticidal activity is the EN1657 with Candida albicans. The minimum requirement is that the teat disinfection solution is effective against bacteria and yeasts. Virucidal activity is an optional claim (full virucidal activity or activity against enveloped viruses) to be performed with the adequate organism following the EN14675 test protocol.
Contact time, interfering substances and temperatures are predefined by the guidance. The purpose is to simulate practical conditions:
- Temperature of 30°C or lower
- Soiling: 10g/L skimmed milk
- Contact time is 1 minute, a maximum of 5 minutes is accepted
In the suspension test protocol, the teat disinfectant solution is mixed together with the pathogens to be tested. The number of Colony Forming Units (CFU) is counted after neutralization of the solution. The required log10 reductions is log 3 for yeast and log 4 for bacteria. With a starting point of a million of bacteria, a 3-log kill reduces the colony to 1,000 bacteria after a 99.9% reduction, and a 4-log kill reduces the colony to 100 bacteria after a 99.99% reduction.
As described in the Biocidal Product Regulation guidance, volume II Efficacy – version 4.1 of February 2022: “no European standard phase 2, step 2 tests are available for teat disinfection. To demonstrate efficacy, phase 2, step 2 tests should be provided with a test design relevant for the use. The test design must reflect the application and should be discussed with and agreed by the Competent Authority before testing takes place.”
The main actives substances
Iodine have been used for more than 150 years as antiseptic. It is still the most widely used teat solution worldwide. Iodine is a halogen and is generally unstable in water. At least seven iodine species can be found in aqueous solution, in a complex equilibrium, with hydrated molecular iodine (I2) being responsible for the bactericidal activity (7). Iodophors or iodine complexes have been acting as a reservoir of active “free” iodine in solution and also help preventing negative effects of iodine on the teat skin.
Concerning the EU biocide regulation, iodine based products are registered under the active substance: iodine (CAS number:7553-56-2) or under the active substance: Polyvinylpyrrolidone iodine (PVP-iodine) (CAS number 25655-41-8). Both substances have been approved for PT-1, PT-3, PT- 4 and PT-22. Currently, in the PT-3 category, 211 dossiers have been authorised for iodine, and 149 dossiers authorised for the PVP-iodine.
The assessment report of ECHA describes the mode of action of iodine as being non-specific, implying that the development of resistance is unlikely. Here are some of the working mechanisms of iodine as a disinfectant:
- Iodine rapidly penetrates microorganisms showing a high affinity pattern of adsorption.
- Iodine combines with protein substances in the bacterial cell; these could be peptidoglycans in the cell walls or enzymes in the cytoplasm. This results in irreversible coagulation of the protein and consequent loss of function. Iodine also reacts with thiol groups in the metabolic chain and interferes at the level of the respiratory chain of the aerobic microorganisms.
A practical aspect is the colour of iodine solution: the germicidal activity of iodine-containing solutions is characterized by their colour. Amber solutions are active whilst pale yellow or colourless solutions are less effective and must be replaced by new solutions.
Chlorhexidine has been widely used in antiseptic products, in particular in handwash and oral products. This is due to its broad-spectrum efficacy and low irritation towards skin. Chlorhexidine is well known as a bactericidal agent, and chlorhexidine gluconate is rapidly acting on bacteria (7).
Concerning the EU biocide regulation, chlorhexidine (CAS number: 18472-51-0) has been proposed for PT-1, PT-2 and PT-3 uses. Chlorhexidine based products have not yet been assessed under the new biocide regulation (9). Dairy producers should still refer to national authorisations.
Chlorine is one of the most significant microbicidal halogens and has been traditionally used for both antiseptic and disinfectant purposes. Chlorine dioxide is a highly active oxidizing agent (7).
In a teat dip solution, chlorine dioxide is a gas solubilized in the solution. Chlorine dioxide is well known in water disinfection to penetrate the slime layers of the biofilm. Used as a teat dip, we can assume that its gaseous form allows an in-depth disinfection in the skin and teat end surroundings.
Concerning the biocide EU regulation, chlorine dioxide (CAS number 10049-04-4) has been proposed for PT-2, PT-3, PT-4, PT-5, PT-9, PT-11 and PT-12 (10). The initial application for approval is in progress. Chlorine dioxide based products have not yet been assessed. Dairy producers should still refer to national authorisations.
Lactic acid is often seen as the ideal candidate as a green biocidal agent.
In the US, lactic acid is classified by EPA as a biochemical pesticide due to its non-toxic mode of action, natural occurrence in the environment and history of exposure to humans and the environment demonstrating minimal toxicity. It is also classified as an antimicrobial pesticide and is used as a disinfectant, indirect food contact surface sanitizer, fungicide and virucide on hard, non-porous surfaces.
The ECHA distinguishes 2 active substances: the lactic acid and L-(+)-lactic acid.
Lactic acid (CAS number 50-21-5) is a racemic mixture of L and D forms. It is considered as a non-dangerous chemical and the registration of formula based on this active is made via a simplified procedure. Today a few teat dips have been registered under the simplified procedure (11).
The L-(+)-lactic acid (CAS number: 79-33-4) has been approved for PT-1, PT-2, PT- 3, PT-4 and PT-6. Currently, in the PT-3 category, 13 dossiers have been authorized (12).
The assessment report of ECHA describes the mode of action of L-(+)-lactic acid as non-specific, and consider the development of resistance unlikely. In solution, L-(+)-lactic acid exists in a pH-dependent equilibrium between the undissociated and dissociated form. At a low pH, uncharged acid enters the cell, lowers the pH of the cytoplasm, and inhibits the metabolic reactions.
The teat dip cup should be as clean as possible in order to safeguard the bactericidal activity of the disinfection.
The mode of action of salicylic acid is similar to lactic acid. The non-dissociated salicylic acid penetrates the bacteria and yeast, decreasing the pH and disturbing the cell functions. Since the mode of action is based on the non-dissociated form of salicylic acid, pH of the disinfectant should be lower than 3. Overall, bacterial resistance is unlikely to occur.
Concerning the EU biocide regulation, salicylic acid (CAS number: 69-72-7) has been proposed for PT-1, PT-2 and PT-3 uses. The biocidal product committee has given a positive opinion regarding the use of salicylic acid as a ready-to-use product to disinfect teats before or after milking. The assessment outcome is in progress (13).
Peracetic acid, hydrogen peroxide or biphenyl-2-ol are approved by the Biocidal Products Committee as active substance for Product type 3 (14) (15) (16). However, the intended uses are surface disinfections. The application on the skin as a post-milking teat disinfection is not described.
Combination of several active substances
There is a tremendous increase in the availability of dual active substance products on the European market. While some combinations are known to be synergistic, other combinations might be offering the marketing authorization holder an opportunity to delay the deposit of the registration dossier as combined active substances are postponed to the last active substance deadline. Therefore, the level of each active compound should be analysed critically to evaluate the benefit of the dual active formulation.
Skin barrier is an essential defence mechanism against exterior aggressors. A study by Abdul et al, published in 2010, suggests an association between intramammary infections at calving and the presence of hyperkeratotic teat-end lesions, derived from the fact that Staphylococcus aureus, non-aureus staphylococci, Streptococcus uberis, Streptococcus agalactiae and Escherichia coli were significantly more often cultured from more quarters with these kind of hyperkeratotic teat-end lesions than from quarters without such lesions or with other types of lesions (17).
Milking routine, weather conditions or products that come into contact with the teat skin can affect the teat skin condition.
The impact of weather conditions can strongly vary depending on the housing system due to factors such as wind exposure or humidity level. Exposure to cold temperatures may results in dry and chapped teats. The post-milking teat disinfection fact sheet published by NMC describes well the importance of choosing a teat dip adapted to the farm and weather conditions (3).
Active substances impact the lipidic film present on the skin. Therefore, emollients are important ingredients of teat dip formulations. An emollient is a substance that helps soothe, soften, and increase moisture levels, in the skin. Let’s have a look at the most common emollients added in post-milking teat disinfection.
Glycerine or glycerol is a primary component of triglycerides, naturally-occurring fats present in most lipid-rich substances. It’s a thick, viscous texture, making it a popular ingredient in a wide range of products, including food, medications, and skincare. Glycerine is use as a humectant: it works by drawing water from the atmosphere to hydrate and soften the skin. Glycerine penetrate the first layers of the skin to provide continuous hydration. It is recognized in the International Nomenclature Cosmetic Ingredient as a substance having skin conditioning and skin protecting properties (19).
Sorbitol, a well-known ingredient of the cosmetic industry, is another emollient used in teat dip composition. It acts as a natural humectant, thanks to its water-binding capacity. It attracts water from the air and binds it to the skin cells, slowing the evaporation process. Sorbitol is naturally present in fruits such as plums, apples or cherry and is industrially produced by hydrogenation of corn syrup or glucose. It is also used as a food additive under the name E420. It is recognized in the International Nomenclature Cosmetic Ingredient as a substance having humecting, skin conditioning and skin protecting properties (20).
Lanoline, from animal origin, is also called wool fat or wool wax, it is obtained by purification of the fat part of the wool. It helps to form emulsions and blends well. Lanoline is used to moisturize the skin. It has also surfactant properties: it reduces the surface tension between the product and the skin and contributes to a proper coverage. It has some adhesive characteristics. it is also used a food additive E913. Some of the INCI functions described in the INCI include: emollient, emulsifying, skin conditioning and surfactant properties (21).
Propylene glycol is from a vegetal or synthetic origin. It works as a humectant: maintaining the water content of the product on the skin, as a skin conditioning agent and solvent and viscosity controlling agent in the formulation of the solution. Propylene glycol is also a food additive E1520. It is recognised in the International Nomenclature Cosmetic Ingredient as a substance having humecting and skin conditioning and skin protecting properties (22).
Aloe vera, a gel extract from the leaves of the plant of the same name, has excellent moisturizer properties. Aloe vera is described in the INCI as an emollient, an humectant and a skin conditioning agent (23).
Regular monitoring and recording of teat skin and teat end condition are advised, at least 2- 3 times per year to select the adequate post-milking teat disinfectant in function of the season, housing conditions, milking routine effects on the teat condition.
Teat disinfecting solutions range from water-like solution to creamy formulations with more or less film forming properties. Barrier teat disinfectants are designed to leave a protective film on the teat and teat sphincter for a certain period of time between two milkings. Some emollients act as viscosity enhancers which is for instance the case for propylene glycol or glycerine. Other substances may be added to obtain a residual film which might still be present at the next milking.
The main purpose of applying the teat dip after milking is to prevent teat skin and teat end colonization by bacteria. Considering that the bacteria have been deposed on the teats during milking, the goal is to disinfect the entire surface of the teat that has been in contact with the teat liner. The teat shape is rapidly evolving after milking, bacteria present on the teat surface become less accessible a few minutes after milking. Therefore, the sooner after milking cluster removal the teats are disinfected, the more effective.
Emily Krekelberg, from the University of Minnesota, describes a way to validate the coverage, the so-called White Towel Test (24):
- Immediately after the teats have been dipped or sprayed, wrap a clean towel around the base of the teat
- Make sure to blot the teat dip from the entire teat.
- Unwrap the towel and open it to display the teat dip pattern.
The purpose is to get a continuous shape. If the pattern shows incomplete coverage, training should be implemented to show the milkers the proper procedures.
How long should the teat dip stay on the teats?
The answer to this question is farm-specific.
In case of contagious mastitis, the udder is the predominant infection source and the bacteria are primarily spread via contaminated milk on the teat skin during milking. The transfer of bacteria between animals occurs via the teat liners, cloths used to wipe the teats, and the hands of milkers. In this situation, consistent, fast and complete teat coverage at each milking is the target.
If the main challenge is environmental mastitis, and if the cows are housed in challenging environmental conditions (i.e. high stocking density, warm and humid conditions), barrier teat disinfectants will be of added value. To prevent penetration of bacteria present in the environment into the udder, long term coating is desirable. How to measure the effect? Check the teats at the next milking: are there still pieces of the barrier dip visible on the teats?
Inadequate teat coverage
Although considered as a simple step of the milking routine, teat dipping or spraying is often not done properly. Every consultant that is paying particular attention to post-milking teat disinfection has seen dirty dip cups, dirty teat solutions and inadequate/blocked spray systems resulting in poor teat coverage. The effectiveness of post-milking teat disinfection relies on the complete coverage of the teats. Whether post-milking teat disinfection is performed manually or automatically, it is recommended to set a quality control scheme to get the most out of this effective prevention measure. Table 2 proposes a “post-milking teat protection evaluation sheet”.
Table 2. Example of a post-milking teat protection evaluation sheet.
Make sure the application devices are clean
Dip cups should be as clean as possible. There is often a false idea that disinfecting material does not need to be cleaned as it is meant to get rid of pathogens. However, when there is a layer of 2 mm of dirt in the bottom of the cup, the disinfectant will be working on this organic matter, and will barely be effective in killing the bacteria on the teat skin. Hygiene is even more critical if return cups are used.
With spray devices, the principle is the same: keep the spray nozzle as clean as possible. Each teat spray solution has a different viscosity, implying that the spray pattern will vary. It is necessary to adjust the system parameters to obtain the optimum teat coverage. Check the spray pattern to make sure that the spray device disperses the solution properly by spraying upwards onto a sheet of paper (approx. 15-20 cm distance). A solid cone of spray should be achieved.
The spray pattern can be checked by spraying upwards onto a sheet of paper (approx. 15-20 cm distance) (left). A solid cone of spray should be achieved (right).
Concentrate forms are usually more interesting from an economic point of view. Still, they require an extra preparation step before teat solution is ready-to-use. On farms that make use of concentrate forms, it is essential to have a quality control in place in order to avoid over- or under-dilution. A detailed factsheet has been written by NMC regarding the proper storage and handling of teat disinfectants (25).
Make sure to use water of drinking quality to dilute the concentrate form. If the water is of poor microbiological quality, the disinfectant will already lose part of its activity in the solution before it ends up on the teats. Mineral load can also have an impact on the chemical stability of the solution.
Mixing chemicals that are not intended to be mixed can cause a loss of efficacy. Disinfectants are non-specific reactive substances, and a change of pH for instance may impact the equilibrium of the formula and decrease the disinfecting properties. Mixing chemicals can also create aggressive by-products. When there is a change of teat spray, it is recommended to flush the spray devices with lukewarm water to avoid involuntarily mixing chemicals in the tubes.
Robotic milk spraying
Not all the teat disinfecting solutions can be used with each and every kind of device. Viscous or barrier solutions have a higher risk of blocking pipes and tubes. It is best applied thanks to a non-return dip cup. A liquid solution is usually applied with a spraying device, but it can also be applied with a dip cup.
When the application is performed manually, the challenge is to obtain a systematic application without spending too much time or wasting too much solution. In-liner automated teat disinfection gets rid of the human factor. The manufacturer of such systems claim proper coverage, consistency, and economical and fast application as the teat spray is applied specifically on the teats while the teat liners are still attached.
The principles as the advantages of post-milking teat disinfection are well-known. Only the combination of all properties of the teat dip/spray formulation together with a correct application leads to effectiveness.
When it comes to post-milking teat disinfection, the traditional recipe is still the best:
- Select quality ingredients, a proven disinfecting solution, a pinch of emollients, and a dash of film-forming agents if required based on the farm circumstances and practices.
- Then apply it consistently, after each milking to obtain one of the most relevant mastitis prevention measures!
- Bradley, A. J. (2002). Bovine mastitis: an evolving disease. The veterinary journal, 164(2), 116-128.
- NMC https://www.nmconline.org/2020/10/06/nmc-updates-post-milking-teat-disinfection-fact-sheet/
- Fitzpatrick, S., Garvey, M., & Gleeson, D. (2018). A review of test protocols for the evaluation of teat disinfectants. International Journal of Dairy Technology, 71(3), 553-563.
- Schwenker, J. A., Schotte, U., & Hölzel, C. S. (2022). Minimum inhibitory concentrations of chlorhexidine-and lactic acid-based teat disinfectants: An intervention trial assessing bacterial selection and susceptibility. Journal of Dairy Science, 105(1), 734-747.
- FDA https://www.fda.gov/regulatory-information/search-fda-guidance-documents/cpg-sec-654200-teat-dips-and-udder-washes-dairy-cows-and-goats
- Antiseptics and disinfectants: Activity, action and resistance, G. McDonnell et al., Clinical microbiology reviews, 1999, 147-179
- ECHA Iodine PT3 Assessment report https://echa.europa.eu/information-on-chemicals/biocidal-active-substances/-/disas/factsheet/1319/PT03
- ECHA Chlorhexidine https://echa.europa.eu/information-on-chemicals/biocidal-active-substances/-/disas/factsheet/1288/PT03
- ECHA Chlorine dioxide https://echa.europa.eu/information-on-chemicals/biocidal-active-substances/-/disas/factsheet/1477/PT03
- Lactic acid ECHA simplified procedure https://echa.europa.eu/information-on-chemicals/biocidal-active-substances/-/disas/factsheet/1421/null
- Lactic acid ECHA https://echa.europa.eu/information-on-chemicals/biocidal-active-substances/-/disas/factsheet/1322/PT03
- Salicylic acid ECHA https://echa.europa.eu/information-on-chemicals/biocidal-active-substances/-/disas/factsheet/1376/PT03
- Biphenyl-2-ol ECHA https://echa.europa.eu/information-on-chemicals/biocidal-active-substances/-/disas/factsheet/1249/PT03
- Hydrogen peroxide ECHA https://echa.europa.eu/information-on-chemicals/biocidal-active-substances/-/disas/factsheet/1315/PT03
- Peracetic acid ECHA https://echa.europa.eu/information-on-chemicals/biocidal-active-substances/-/disas/factsheet/1340/PT03
- Abdul L. Bhutto, Richard D. Murray, Zerai Woldehiwet, Udder shape and teat-end lesions as potential risk factors for high somatic cell counts and intra-mammary infections in dairy cows, The Veterinary Journal, Volume 183, Issue 1, 2010, Pages 63-67.
- Glycerine https://incibeauty.com/en/ingredients/6832-glycerin
- Sorbitol https://incibeauty.com/en/ingredients/18826-sorbitol
- Lanolin https://incibeauty.com/en/ingredients/6281-lanolin
- Propylene glycol https://incibeauty.com/en/ingredients/5327-propylene-glycol
- Aloe vera https://incibeauty.com/en/ingredients/2223-aloe-barbadensis-leaf-extract
- , Timing the milking procedure, 2020 https://extension.umn.edu/dairy-milking-cows/timing-milking
- Guidelines for Proper Storage and Handling of Teat disinfectants, NMC, https://www.nmconline.org/nmc-protocols-guidelines-and-procedures/