Pus in Milk?

By Guest Blogger   |  8Comments|

In‘s video-of-the-day today, 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 of the year (including seven 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, one in six dairy cows in the United States suffers from clinical mastitis, which is responsible for one in six 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, “almost always” caused by mastitis. When a cow is infected, greater than 90 percent 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.

* 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., is a physician, author and internationally recognized speaker on healthy eating. Hundreds of Dr. Greger’s nutrition videos are freely available at, with a new video posted every day! All the proceeds from the sales of his books and DVDs are donated to charity.

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8 responses to Pus in Milk?
  1. Watch this:

    Never mind the doctor’s tall frosty glass; picture a vet lancing the cow’s infected udder, draining blood & pus, filling up a BUCKET. For four minutes.

    It’s a dose of truth so intense, YouTube doesn’t want kids to see it.

    Been meaning to break up with dairy? Watch this.

  2. Oh, that poor animal!

    Please note, though, vetstud[ent?], that a cow with such an advanced case of mastitis would be excluded human milk supply.

  3. Seriously – gag. I knew there were numerous reasons dairy wasn’t for me… didn’t realize pus was one of them. Yuck. Milk is GREAT – for baby cows.

  4. Do any dairy producers hand milk their cows anymore?

  5. Today, I’m going out on a limb to suggest a new kind of Doctor-Patient Relationship

    interesting way to simply speak your truth in 2011, commentary on the practice of medicne and our health care sytem,,,? going out on a linmb? please clarify where that is coming from and what it means, thanks
    agree 100% with statement…bravo!!!

  6. What a wonderful piece from a knowledgeable authority! Thanks, Dr. Greger!

  7. Okay please keep in mind that these problems and stressed out cows do not extend to every single US dairy. These problems can usually be found in places where dairy cows are kept on an industrial level. there are plenty of small local dairy producers who care a great deal about the quality of life their cows live and the quality of milk they produce. You need only to put a little bit of research into where you are buying your milk. Some companies are good at networks with small local dairies some are not.

    Also keep in mind that is there no “natural pregnancy” cycle for a dairy cow. Dairy Cows were created by man through selective breeding to do one thing, produce milk, and lots of it. Most dairy cows can’t even give birth unassisted by the human hand. To say that the milking/pregnancy cycle stresses the cow out is not true. The cow was bred to be able to physically produce milk 10 out 12 months of the year – yes, even though a pregnancy without undue stress to itself. When you take into account most small dairy farmers treat and feed their cow better than my own dogs, a healthy dairy cow has no health issues what so ever with this cycle.

    Also not all dairy cows are sold to become hamburger at the two-year mark. In big industrial dairies, yes this does happen. In smaller local dairies it rarely does. A dairy cow can remain productive for many years if treated right, and when production drops below what a smaller dairy required lots of small dairy resell their cows to people looking for a family milk cow that doesn’t produce the typical 8 gallons a day, though eventually some do go to slaughter, that is not the end goal.

    It’s always important to give both sides of an issue when discussing such things. There are many other arguments one can use to dissuade people from drinking milk without labeling and entire industry as evil, and it doesn’t take that much time either, it took me 7 minutes to type this up.