How much pus is there in milk?

How much pus is there in milk

In the new video-of-the-day, I note that the antiseptics used to disinfect cow teats can provide a source of iodine, but have been found to boost the level of pus in the milk of cows with staph-infected udders. Today’s dairy cows endure annual cycles of artificial insemination, pregnancy and birth, and mechanized milking for 10 out of 12 months (including 7 months of their 9-month pregnancies). This excessive metabolic drain overburdens the cows, who are considered “productive” for only two years and are slaughtered for hamburger when their profitability drops, typically around their fourth birthday, a small fraction of their natural lifespan.

Turning dairy cows into milk machines has led to epidemics of so-called “production-related diseases,” such as lameness and mastitis (udder infections), the two leading causes of dairy cow mortality in the United States. We all remember the Humane Society of the United States investigation showing sick and crippled dairy cows being beaten and dragged into the California dairy cow slaughter plant en route to the national school lunch program, triggering the largest meat recall in history. That loss of body condition is a result of the extreme genetic manipulation for unnaturally high milk yields.

Because of the mastitis epidemic in the U.S. dairy herd, the dairy industry continues to demand that American milk retain the highest allowable “somatic cell” concentration in the world. Somatic cell count, according to the industry’s own National Mastitis Council, “reflects the levels of infection and resultant inflammation in the mammary gland of dairy cows,” but somatic cells are not synonymous with pus cells, as has sometimes been misleadingly suggested. Somatic just means “body.” Just as normal human breast milk has somatic cells—mostly non-inflammatory white blood cells and epithelial cells sloughed off from the mammary gland ducts—so does milk from healthy cows. The problem is that many of our cows are not healthy.

According to the USDA, 1 in 6 dairy cows in the United States suffers from clinical mastitis, which is responsible for 1 in 6 dairy cow deaths on U.S. dairy farms. This level of disease is reflected in the concentration of somatic cells in the American milk supply. Somatic cell counts greater than a million per teaspoon are abnormal and “almost always” caused by mastitis. When a cow is infected, greater than 90% of the somatic cells in her milk are neutrophils, the inflammatory immune cells that form pus. The average somatic cell count in U.S. milk per spoonful is 1,120,000.

So how much pus is there in a glass of milk? Not much. A million cells per spoonful sounds like a lot, but pus is really concentrated. According to my calculations* based on USDA data released last month, the average cup of milk in the United States would not be expected to contain more than a single drop of pus.

As the dairy industry points out, the accumulation of pus is a natural part of an animal’s defense system. So pus itself isn’t a bad thing, we just may not want to have it in our mouth.

And you can taste the difference. A study published in the Journal of Dairy Science found that cheese made from high somatic cell count milk had both texture and flavor defects as well as increased clotting time compared to milk conforming to the much more stringent European standards. The U.S. dairy industry, however, insists that there is no food safety risk. If the udders of our factory-farmed dairy cows are inflamed and infected, industry folks say, it doesn’t matter, because we pasteurize—the pus gets cooked. But just as parents may not want to feed their children fecal matter in meat even if it’s irradiated fecal matter, they might not want to feed their children pasteurized pus.

-Michael Greger, M.D.

Image credit: jenny downing / Flickr

PS: With my Fall speaking tour ramping up this week, I’m going to have to scale back to just a new video every weekday given my unreliable internet access on the road. But do check back on weekends as I’ll post some of the most popular Q&A that accumulated throughout the week. If you start experiencing withdrawal symptoms, get your fix with our 1,149 topic tag cloud.

* According to the new USDA data, the American milk supply averages 224,000 somatic cells/ml (based on bulk tank samples taken from whole herds). Subtracting the 200,000 that could be present in nonmastitic milk and subtracting the non-inflammatory fraction (10%) leaves us with 21,600 neutrophils per ml, and multiplying that by the volume of milk in a cup (237ml) comes out to be about 5 million neutrophils per cup. Then it depends on the cellular concentration of pus. Pus usually has more than 10,000 cells/microliter, but “In purulent fluids, leukocyte count is commonly much lower than expected because dead cells or other debris account for much of the turbidity,” and so apparent “pure pus” may have <10,000 cells/microliter. Conservatively using what was described in the medical literature as frank pus (80,000 cells/microliter) and converting from microliters to drop (50 microliter/drop) would mean 4 million cells per drop. Assuming the excess neutrophils drawn to the infected udder are pus-forming, 5 million divided by 4 million equals little more than a single pus-drop per cup (though I guess that could mean as much as 2 or 3 per tall frosty glass). 

  • Michael Greger M.D.

    For pus-free sources of iodine, please see Avoiding Iodine Deficiency and Too much iodine can be as bad as too little. There are also more videos on dairy. And as always, feel free to leave questions or comments below.

  • vetstud

    Only a drop, doc? Looks more like a BUCKET of pus to me:

    • Michael Greger M.D.

      Yikes! The poor thing. Towards the end it looks like soft-serve ice-cream coming out :(. Definitely not for the squeamish. Even though milk is pooled together at a herd level and loaded into tanker trucks, a cow with such an advanced case of mastitis would be excluded from the human milk supply.

  • JUst another reason I am vegan!

  • Another reason why I dont drink milk!

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  • Sophiabloodmoon


  • James Thompson

    Looking at the original USDA report it looks like the 1 in 6 number is the percentage of cows that died from mastitis not the number of cows in the herd with mastitis. However subclinical mastitis also raises the somatic cell counts and as the Merck Veterinary Manual says: “All dairy herds have cows with subclinical mastitis; however, the prevalence of infected cows varies from 15–75%” (

  • mike88

    Has there ever been a test or comparison of the amount of pus in pasteurized milk compared with the amount of pus in Raw un-pateurized milk, and if so, was the comparison equal amounts of milk and taken at the same time and from the same utter area. I would like to see the results of that test if there has been one done.

  • JustTheFacts

    Our SCC averages around 70, 000 for the year but we’ve had test as low as 16, 000 and a monthly average as low as 26, 000! We use iodine dip, antiseptic wipes, soap with a small amount of bleach so your whole argument that this will increase SCC levels is complete bullshit! Clearly you don’t milk cows for a living and haven’t a clue like most people how ultra low SCC levels are achieved.

    As for altering taste …. again bullshit … usually nasty dairies that have SCC problems also have bacteria issues to boot and when the milk is pasteurized, it’s the killed bacterica along with an enzyme that gives the milk an off favor which also shortens shelf life!

    Feeding corn silage is what truely alters the taste …. sours the milk so to speak hence the reason for the great demand for grass feed only milk.

    If I were you I’d refrain from giving advice on dairy farming … lol … you clearly don’t have a freaking clue. Better yet, buy a dairy farm and see how little you really know …. put your money where your mouth is and see how long it takes you before you go bakrupt =)

    • Tommasina

      Just The Facts, I’m all for sharing information, but I’d appreciate if this could be a safe forum for everyone. Please no insults. Thanks!

    • Alex

      Dairy farmers tend to lie through their teeth. And I wouldn’t trust anyone who rapes cows and takes their young and steals their milk for a living.

      • ruth behr

        Let’s play nice here, children…

  • cow fucter

    So let’s look at some basic science here. What is a “pus cell”? Pus
    is made up of dead white blood cells, bacteria and dead skin cells.
    Gross right? That’s what the anti milk people want you to think about
    when they spout their bologna. So, there really isn’t a single “pus
    cell” like this charming infographic would like you to believe, instead
    pus is a combination of things. A white blood cell is a normal part of
    blood. White blood cells are not pus. There are white blood cells in
    milk, In the dairy industry we closely monitor what we call the somatic
    cell count (SCC) of our cows and our milk. Somatic cell count (SCC) is a measurement of how many white blood cells are present in the milk. White blood cells are the infection fighters in our body and so an elevated white blood cell presence or on a dairy farm an elevated SCC is a signal that there may be an infection that the cow is fighting.

    Dairy farmers are paid more money for milk that has a low SCC, if our
    cell count raises above normal levels they will dock the amount we get
    paid for our milk, if it raises even higher they stop taking our milk
    and we can’t sell it. So not only do we not want our cows to be sick, it
    would cost us a lot of money and could cost us our farms if we were to
    ignore a high SCC. Recently the dairy industry lowered the acceptable
    SCC level from 750 to 400. Most dairy farms aim for a SCC under 200. So
    does this mean that we are allowing some pus into your milk? No. All
    milk is going to have some white blood cells in it, that’s the nature of
    a product that comes from an animal, cells happen. It does’t matter if
    it’s organic milk or regular milk. The presence of some white blood
    cells in milk certainly doesn’t mean that the animal is sick or the milk
    is of poor quality. Again, white blood cells are normal. Additionally
    when you buy milk from the store it has been pasteurized which kills off
    any white blood cells or bacteria that are present in the raw milk.

    So the anti milk folks want to you to be grossed out by milk, but
    think about this… A steak has white blood cells in it, because it has
    blood and white blood cells are a part of that. The anti milk people
    aren’t going around saying that your steak has pus in it because we can
    see with our own eyes that it doesn’t. However, since we can’t see into
    our milk like we can see a steak, anti milk activists use bad science to
    scare you into believing their view point and that’s just not right!

    Instead of using facts to persuade people to not drink milk they are
    literally trying to make you terrified to eat or drink anything beyond
    what they feel you should be eating and drinking. It’s time to take back
    our food from the activists and let them know that it is not ok to use
    false information to slander a food they don’t agree with. My cows are
    mad and so am I!

    • Chris

      Nicely said.

    • Kim

      Nice plagiarism.

    • A

      You only half debunked one of the MANY reasons to stop eating milk and dairy…

      • lisa

        Well listen we have been drinking milk since a child no one has died from it so you know… mother milk humans I am sure made the same way. And it was made for us the first year of our life we still here so u will live …if you new the vegetables you eat was fertilized with cow crap and you still eat it what the difference? That is for vegetarians as well cheers

    • Jason Ashby

      Milk is for babies and it does not do a body good.

    • Rascal

      Just a little problem with your story. You keep referring to the milk as “our” milk. It is not and was never your milk to begin with. You stole it from the cow you raped to produce it. Sick.

    • Henry Thostason

      OK then, let’s not think about the pus. Let’s think about the cows who are being systematically inseminated and slaughtered for your “need” to have meat and milk. I cannot believe the amount of “educated” people who are so naive and ignorant about this. I’ve got an idea. Let’s see the Dairy Farmers show us a video of their milk production, ANY milk production facility, so they can show us once and for all that the cows are being treated humanely. I’ll be waiting.

  • Heroic Hal

    In other words, there’s no reason to be alarmed about it, but it’s still only fair to sound an alarm so that people who are alarmed by things there’s no good reason to be alarmed about have the opportunity to be unduly alarmed anyway and avoid the thing there’s no reason for them to avoid. Because it’s very important to avoid that one drop of harmless liquid when one is drinking one’s glass of sweat. Oh, gosh, yes, why not warn all current and future nursing mothers that their breast milk is, after all *sweat*. Then they can fear that too.

    • Henry Thostason

      Again, let’s forget about the pus. Let’s focus on the treatment. Show me a video where the Dairy Farmers Association are treating cows humanely. Its pretty stupid to drink milk (and intentionally ignore where it came from and how) when you can have rice milk, almond milk, soy milk, rice milk, coconut milk. Get it?

      • scaughie

        Get what?? Rice: grown primarily in Asia, where people are paid a pittance to farm and harvest it. Often little better than slave labor. Almond milk: love it, but it’s primarily made (for the US market) from almonds grown in CA at a HUGE water cost, more or less equivalent to raising cattle, and this in a state with years of drought under its belt and many more to come if we believe predictions. Soy: often GMO, full of estrogens (drinking 2 cups a day is equivalent to taking a birth control pill in estrogen content) plus soy farming is quite destructive to the environment. Coconut: aside from human rights issues, this ‘milk’ includes Bisphenol-A, guar gum and leads to frustose malabsorbtion. And just in case you’re wondering, I have Crohn’s and I’m on a dairy, gluten, red meat free diet, plus low fat and strong warnings to avoid alcohol. So I am not a dairy ninja. Also, I have also been a vegetarian since age 12 – that was 30 years ago, wince! – so yes, I know what I’m talking about. The fact is, the plant-based ‘milks’ are rarely a better option for the environment than animal based ones. My kids, btw, were allergic to both cow based and soy based formulas as babies, when weaning started causing problems. That was all you could get in the UK then. Do I abhor the treatment of farm animals? Absolutely. But before you start calling people stupid, consider the cost of what YOU use! Have a look at the link below. And if you truly need more documentation, believe me, I can supply it. BTW I wouldn’t be picking on you if you hadn’t called people ‘stupid’ for not drinking plant-based ‘mllk’…

        • Peter Singh

          Mallisena uses the parable to argue that immature people deny various aspects of truth; deluded by the aspects they do understand, they deny the aspects they don’t understand. “Due to extreme delusion produced on account of a partial viewpoint, the immature deny one aspect and try to establish another. This is the maxim of the blind (men) and the elephant.

        • Gretel

          This is interesting and depressing. : / Can you point me toward articles about cashewmilk?
          *nervously maintaining some hope!*

  • EMDPS2323


  • Jane doe

    Get educated everyone. If we all start drinking any one of the delicious and satisfying plant-based milks, we can save these lovely animals from horrific treatment. Please, go vegan. Or just be humane in how you eat. We have so many choices. We can change the world.

  • Hillary Rettig

    the NMPF page has been mysteriously scrubbed, but you can still find their press release on successful efforts to fight pus reduction on the Wayback Machine: