Milk Myths Debunked – Part 1: Is There Pus in Milk?


Perhaps you have read or heard that milk contains pus. Articles like this one from have certainly played their part in spreading this myth, claiming that mastitis runs rampant in the dairy industry and that the milk from these cows is saturated with pus (along with the highly inaccurate claim that most cows are only productive for two years). Perhaps you’ve seen inflammatory infographics like this one:

A dairy friend of mine says that the NotMilk website is aptly named: it is most certainly not milk what they describe there! A dairy friend of mine says that the NotMilk website is aptly named: it is most certainly not milk what is described there! And that bit about casein: human breast milk also contains casein. It’s not likely to be deadly, is it?!

Maybe you’ve even had the dubious pleasure of watching the same video I have, where the somber voice over gleefully chortles about the millions of pus cells present in each glass of milk.


So…Is there pus in milk??? Absolutely not. As a dairy farmer, I work with our cows and their milk daily, and I know that this is not true. Allow me to explain…

Where do these rumours begin? Like all mammals, cows produce milk after giving birth. Sometimes a cow will develop an infection of the udder called mastitis. For those familiar with breastfeeding, you’ll know that humans too can develop mastitis. This accurate definition from Wikipedia sums up mastitis clearly and succinctly: “Mastitis occurs when white blood cells are released into the mammary gland, usually in response to an invasion of bacteria of the teat canal. Milk-secreting tissue and various ducts throughout the mammary gland are damaged due to toxins by the bacteria. Mastitis can also occur as a result of chemical, mechanical, or thermal injury. The udder sac is hard, tight, and firm. This disease can be identified by abnormalities in the udder such as swelling, heat, redness, hardness or pain if it is clinical. Other indications of mastitis may be abnormalities in milk such as a watery appearance, flakes, or clots.” Reading this definition, one can almost understand why a person not familiar with procedures and practices on a dairy farm could be led to believe that there is pus in milk, especially after reading false statistics claiming widespread incidences of mastitis in dairy cows. Yes, cows can get mastitis. It can be a debilitating, even life threatening infection if not treated properly and promptly. As farmers, we take each case of mastitis very seriously. When mastitis is detected, either via testing or the daily visual inspection of each cow’s milk before the milking machine is attached, the milk from that cow does not enter the supply chain until the infection has cleared. Depending on the severity of the infection, there are a few different ways to treat mastitis. If the infection is not too virulent, hot compresses and massages and stripping out the milk from the infected part of the udder can sometimes help the cow get rid of the infection on her own. Other times, antibiotic treatment is necessary. When a cow is treated with antibiotics, her milk also does not enter the supply chain and is discarded until the drug specific withdrawal time has passed. Additionally, all milk is tested on farm and at the processing plant for antibiotic residues; if residues are detected, all contaminated milk is discarded and the farmer responsible pays a hefty fine. Once a cow has recovered and her milk has tested clear of antibiotic residues, her milk is once again shipped to the processing plant.

A healthy udder on a healthy cow. No swelling, hard quarters or redness to indicate mastitis. A few squirts of milk were expressed before milking to check for irregularities in the milk. A healthy udder on a healthy cow before and after milking. No swelling, hard quarters or redness to indicate mastitis. A few squirts of milk were expressed before milking to check for irregularities in the milk. After milking, an antibacterial dip is applied to the teats to prevent bacteria from entering the open teat end.

Is mastitis rampant in the dairy industry? No! Take this blurb from the Code of Practice for the Care and Handling of Dairy Cattle: “Overall goals to strive for are: b) Reduction in the occurrence of clinical mastitis to two or fewer clinical cases per 100 cows per month.” Adherence to the Code is now mandatory on all dairy farms across Canada. These guidelines were written to be realistic and practical for dairy farms. If mastitis were rampant, aiming for an incidence level of less than 2% per month wouldn’t be feasible. We aim to reduce cases of mastitis by ensuring that our cows live in a clean and sanitary environment. We keep their stalls full of fresh, clean bedding; we clean the barns of manure multiple times per day; we utilize sanitary practices during the milking of each cow; we ensure that our milking equipment is properly maintained and serviced, and we apply an antibacterial teat protecting dip after milking when the open teat end could allow the entry of bacteria.

Now, let’s take a look at these “pus cells” that anti-dairy groups claim are in the milk you drink.

To tell you the truth, there is no such thing as a “pus cell”. Pus is made up of dead white blood cells, dead skin cells, and bacteria, not one type of cell.

So to what are these people referring? Generally, these “experts” equate somatic cells with pus cells. Somatic cells are living white blood cells located in the udder of cows. Like all white blood cells, they fight infection so an elevated somatic cell count indicates that the cow is fighting some sort of infection, such as mastitis. Milk is tested both on farm and at the processing plant, and one of the tests run is called a “somatic cell count” test. This test shows the level of somatic cells in a sample of milk. A healthy cow with no underlying infection will have a low somatic cell count (SCC). A cow with a somatic cell count below 100 000 cells per milliliter is considered to be in optimum health by most industry sources, she is not fighting any sort of mammary infection. Ontario’s Ministry of Agriculture, Food, and Rural Affairs states that “bulk tank counts or herd averages of under 200 000 indicate excellent udder health and counts over 500 000 indicate a definite problem with subclinical mastitis.” Most dairies aim to keep their SCC level under 200 000.  An average monthly herd somatic cell count under 250 000 somatic cells per mL is also eligible for a quality bonus paid to the farmer. Typically about 80% of farms in our province receive a quality bonus each month. In Canada, the maximum allowable limit for somatic cells in milk is 400 000. This line is drawn to ensure that sick cows are treated and that their milk does not enter the food chain. Consumers can rest assured that their milk does not contain pus AND that it comes from healthy cows! (Just as an aside: the somatic cell count averages for our herd over our last three SCC tests were:  142 000 (Jan 5), 147 000 (Jan 12), 163 000 (Jan 19) ).

If you are looking for answers about dairy, please be critical. Why is the source presenting this information? Is there an underlying agenda? Try to find the source of the information, and verify that it is from an unbiased agency. Pages that push vegetarian or vegan diets or lifestyles may not be interested in telling the whole truth about dairy. While some may say that this article also is a biased source of information, remember that what I have described here is supported by the scientific and veterinarian communities. You’re welcome to double check my facts!

I hope that I’ve explained this issue clearly and logically. As always, questions or comments are more than welcome in the comments section below!


158 thoughts on “Milk Myths Debunked – Part 1: Is There Pus in Milk?

  1. NotYourMilk says:

    i don’t care .. not your milk !! why not suck them directly from the source !? And what u do with the calves, especially the male ones ? it is just a baby and u take it from his/her mother .. and after some month make it in veal ?! can u imagine a woman all her life to live in a room and to be forcibly impregnated every year so you can take her baby and suck her milk ?!


    • mandy jones says:

      As excuse me. I wasn’t even talking to you in the first place And if you don’t even care, then why did you reply to my comment? Also sucking from a cow’s tits doesn’t seem very safe or clean. Also I don’t have or own a dairy farm ( did I ever mention? Nope). Next time don’t ass-ume. It makes you look stupid. 😀


      • mandy jones says:

        Sorry. Nevermind. I thought you was relpying to be since that your comment was on my gmail, so that’s why I thought it was a relpy towards me.😅


      • Dave says:

        Somatic cells = puss but the worst part about dairy is the casein which is a known carcinogen. Drink milk at your own peril.


  2. Unknown User says:

    People are so stupid. Im very glad this, article cleared things up. This article has nothing to do with veal, but the moron above didnt get their nasty milk fantasy validated so they are bringing up veal? Stupid! Stick to the point, we are discussing milk…. and I appreciate this article and the facts presented.


  3. BeFitAgainSteve says:

    Thank you for explaining the ‘milk puss myth.’
    Can you reference a similar article about the ‘cheese is milk pus’ statements I hear almost every day?


    • Well, cheese comes from milk. So if there is no pus (one letter ‘s’) in milk then there is no pus in cheese either. As a general rule, it would be easier to link people to registered dietitians as they have PhD’s and know what they are talking about. Plus, if someone is trying to convince you to be scared of any particular food, whether it’s milk, sugar, aspartame, etc. it’s a good chance they have fallen for a conspiracy theory (that is making a lot of money).


  4. Lorra says:

    You say, pay attention to the sources of the articles you read as they may be biased and what do they have to gain? I would counter with what do plant based people have to gain? What do vegans have to gain? There is no money in being vegan. There is however, money in dairy farming. Follow the money. And then decide who to trust. The goal of animal activists is to have animals be free as nature intended and not to be used by humans. The goal of animal agriculture is to make money from animal products and slaughtering animals. In this case, it is the dairy industry that has everything to gain by saying that there is nothing wrong with milk. When in fact there is everything wrong with it and the the entire system of dairy and animal exploitation that comes with it.


    • Of course there’s money to be gained in veganism: from the self-proclaimed “experts” who get to sell their books and profit off of people’s ignorance. Never mind the higher-priced vegan food products that are sold.

      Also, simply making money off of something (people need to make a living after all) doesn’t change what the actual science has to say, or what reality is.

      If “nature intended” animals to never be used by humans, why did nature “intend” that humans would exist that would use animals for food, drink, and clothing?

      The goal of the agricultural industry is to sustain human life and livelihood.


    • Rick says:

      Somatic cell count IS NOT pus. Those who have an ideological or commercial reason to want us to fear milk are trying to convince us that SCC and pus are interchangeable terms. You either didn’t read or comprehend the article, or you are being purposely obtuse.


    • Rick says:

      “If there’s no puss in milk, then why is there an acceptable limit”

      A nonsensical question, and I think you know it. Somatic cell count, a measurement of the amount of white blood cells, IS NOT a measurement of pus. The purposeful conflating the two is a transparent semantic distortion. Here is an example of the logic you are using.

      “Football is an activity that carries a high risk of injury, including that 1 out of 100 participants will suffer a concussive injury. Football is an activity that uses a ball. Ping pong is an activity that uses a ball, therefore ping pong is football and is an activity that carries a high risk of injury including that 1 in 100 participants will suffer a concussive injury.”

      Another example: Table salt consists of sodium and chlorine molecules. Swimming pools are filled with water treated with chlorine and therefore contains chlorine. Since salt contains chlorine and swimming pools contain chlorine, when you go swimming you are actually swimming in table salt.

      Here is your argument: Pus is a liquid that forms in infected tissue. Pus contains dead white blood cells, dead skin or tissue cells, and bacteria in a solution. Since pus contains white blood cells, anything that contains white blood cells is pus.

      NO, there would be white blood cells, a somatic cell count, in milk even if an animal were completely free of infection. Infection and pus need not be present for there to be white blood cells.

      Liked by 1 person

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  6. Milk is a product of lactation and is thus meant to keep newborns and babies alive. And only babies of the mother, not other species! It contains cow’shormones. Besides, it contains casein which is addictive and that is why people can’t stop eating dairy. Read about casomorphine.


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  8. Nic Bleeker says:

    What happens to the somatic cells once they have reached the end of their capacity to fight an infection in the mammary glands? These dead somatic cells are what makes up puss as you mentioned in your article. Interested to know.

    Also, is bovine casein the same as human casein? Most dairy allergies (not intolerances) is associated with bovine dairy casein.


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