The Udder Side


One of the main problems dairies have is mastitis. This is inflammation and/or infection in the udder. It may be in just one quarter or in all four quarters. When you think about it, we can have any bacteria or fungus/yeast causing mastitis. A cow’s teat is made to have a 3 mm opening at the end. If we have problems with pressure in the milk barn or have the pressure set too high we can ruin the lower sphincter, and then we will have an opening greater than 3 mm. All it takes is a 4 mm opening for bacteria to gain access to the quarter. Damage from too much pressure in the inflation or milking machine will cause scar tissue to form at the end of the teat. This will look just like a very small donut at the lower sphincter. This animal will be prone to mastitis for the rest of her life.

Now to classify mastitis, we have two different forms: contagious and environmental. Environmental is mostly bugs like E. coli or what is known as acute or toxic mastitis. These types of bugs give off endotoxins as they die. They start dying as we treat with antibiotics, or they overgrow their food source. The cows infected like this are very sick and stand a good chance of dying. Treatment normally consists of supportive care and/or lots and lots of fluids, either by IV or drenched with shock treatment. I have had a better survival rate with this treatment and stripping out the quarters every two hours for the first day or two. This infection is normally caused by environmental bacteria. To prevent we need to keep our cows standing for about an hour after milking. This allows the lower sphincters to close naturally and prevent this. When milking, the sphincters open to allow milk flow, and when done, they can and will take about 1 hour to totally close back down. This type of mastitis causes a very high spike in somatic cell count in the infected cow, and then it will go back down. This cell count will only be elevated for just a few days or so.

Unlike the contagious mastitis which causes a very high cell count that does not go back down. And being contagious, it can and will travel throughout the whole herd. E. coli mastitis is a cow killer, but this kind of mastitis is a dairymen killer (which I mean by putting the dairymen out of business). I will see this mastitis flair up during the dry period, and then the cow will calve in with it. It will cause very extreme congestion in the udder, with hard spots. These hard spots can be abscesses and or scar tissue. Cows with mild forms of this mastitis will decrease in milk production by about 10 to 25 percent without showing clinical signs. Then when your somatic cell count is checked, it will be going very high, above 350,000 or worse. If your cell count goes high enough, your milk can and will be dumped or at least downgraded to manufacturers.

As far as treatment for this contagious mastitis, mostly you only have about a 25 percent chance of successful treatment during lactation. Normally you will run about 75 to 80 percent success at dry off. The only treatment I have had success with during lactation is vaccination. A lot of times this will mean cultures and sent off to a lab and the vaccine is made specifically for your problem. But, in the case of Staph aureous we could use a commercial vaccine. These vaccines have dropped somatic cell counts back down to acceptable values. I have also had them hold for the rest of the lactation. And you can also vaccinate your entire herd with this vaccine. It will last for a while, and then the bugs will change, and we will have to start all over.

But, as always, we need to keep things as clean as we can to prevent disease. Cleanliness is the key, but things happen no matter what.

Dr. Tim E. O’Neill, DVM, owns Country Veterinary Service in Farmington, Ark. To contact Tim go to and click on ‘Contact Us.’


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