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 BC dairy farms, and soon will be all across Canada as well. 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 between 100 000 and 200 000 cells per milliliter is considered to be in optimum health by most industry sources, she is not fighting any sort of 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. 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!


Milk Myths Debunked – An Introduction

Picture this: In early December, the Farmer and I spent a few days in Vancouver attending the BC Dairy Conference. On our way into the city, we stopped at a boutique olive oil and balsamic vinegar shop. Fresh bread dipped in their balsamic and extra virgin olive oil? Ohhh my. But I digress…

While paying for my delicious finds, I asked for directions for the quickest way to our hotel. Over the course of the directions, I mentioned that we were in the city for a dairy conference. The sales lady’s eyes lit up. “Can I ask you a few questions?” she exclaimed. If you know me, you’ll know that this is what I love. Generally, my question answering is limited to social media, so a real question from (quite plausibly) one of our own consumers was overwhelmingly exciting for me. In the vehicle in front of the store, waiting for me to finish my shopping, the Farmer knew that something was up. When I get excited, as some of you who know me ‘in real life’ may know, I tend to become very animated. I gesture a lot, and I speak very quickly, probably too quickly 🙂 He could tell just by watching me that I was having a very interesting conversation.

This woman had some questions for me that I had heard multiple times on social media. Her granddaughter loves milk, but this little girl’s mother, the sales lady’s daughter, was concerned about some of the myths she had heard about milk and refused to purchase milk for her daughter. The grandmother was worried, knowing that milk consumption is a crucial part of any childhood. She explained some of her daughter’s concerns:

“Is there pus in milk?” “Is chocolate milk made from bloody milk?” “I heard that the only reason calcium is present in milk is because it is added to milk. Is this true?” “What about added hormones? Isn’t milk full of hormones?”

As I answered her questions as fully as I could given the limited amount of time we had, my mind worked furiously. I already knew that our consumers need a relevant, local source of information that they can trust about the products that we produce and they purchase, but this really brought that fact home to me. I became even more determined to do my utmost to provide access to this type of information. Before leaving, I gave her my blog address as well as our Facebook page, with an invitation to follow our postings there for information about the dairy industry.

I left that store on that cold December afternoon with a renewed feeling of purpose. Reaching customers like this, with genuine questions, brought a feeling of fulfillment. It was a great start to an amazing conference, where we learned so very much about our industry, met many industry representatives and other farmers, and enjoyed a few days away from the farm and our daily labours there.

Since that chance encounter, I’ve been mulling over how best to reach the consumers who have questions like this. I’ve finally decided to write a series of blog posts regarding the common myths about milk and milk products, starting with the most common one: Is there pus in milk? Over the next few months, I will be adding more topics to this series. As always, if you have any questions, please don’t hesitate to let me know! Additionally, your help in sharing these articles will ensure that consumers looking for answers to these questions will be more likely to find these posts. Thank you!