Ask The Vet

May Be a Short-Lived Problem

Image by Jim Patrico

We had a heifer we had to pull a calf from. We started to milk her to give the calf colostrum, and her bag was hot and hard, and the milk was a brown color. We thought we had an orphan and a cull cow on our hands. We figured the cow had mastitis. We gave the calf a colostrum replacer, and the next day, it was up nursing, and the milk and the bag were almost normal. What do you think was going on here?

Dr. McMillan: I have seen this several times during my 38 years of practicing, and I bet it happens a lot more than we realize since we rarely see the milk of beef cows after calving unless you have a problem. I think this happens more with heavier milkers or those whose bags fill early.

My theory is either inflammation or mild trauma leads to a hemorrhage in the udder in the weeks leading up to calving. As the blood breaks down, the heme pigment in hemoglobin turns to a rusty brown color. It is, after all, an iron-containing molecule. If trauma occurs close to or at calving, the milk may have a pink to red color. It may even have clots in it. It takes very little blood in milk to change color.

I doubt this is an infectious mastitis, and it probably does not need to be treated. I also think if this cow completes a normal lactation and raises a good calf, this problem is not likely to recur.

I have a cow with pink eye. None of the others are affected. I have given her two different antibiotics, but it only seems to have gotten worse. What do I need to do next?

Dr. McMillan: We have a lot of questions about pink eye, but this may be less about pink eye and more about infectious bovine keratoconjunctivitis. When a cow gets an infected or irritated eye, especially in the winter months, I always consider the possibility the eye was scratched eating from a bale of hay, or the cow got seed in her eye. I have removed a lot of things from cows’ eyes over the years. Sometimes grass seed, sometimes another type of foreign object that is stuck behind the third eyelid. Squamous cell carcinoma, or cancer eye, is another common eye problem that can show up any time of the year. None of these things will respond to antibiotics. This is a good example of a case where if your initial treatment doesn’t produce the results you’d expect, get your veterinarian out to take a look. And, when it’s the eyes we’re talking about, sooner is always better.

I have been using loose cattle mineral with an additive for fly control. It will only control horn flies. I want to switch to another product to help control face flies, but both the loose mineral and the supplement blocks I can find that will do this contain the active ingredient Rabon. The label says before using Rabon with pregnant or nursing cows, you are supposed to consult a veterinarian. I have a small cow/calf operation, and most of our cattle are pregnant or nursing, so I’m not sure what to do. I don’t use ear tags, but I do use a fly rub-scrub with strips and bullets on it. I also make direct applications on an as-needed basis. These products are permethrins.

Dr. McMillan: You are correct that Rabon can help with the control of face flies. I talked to a veterinarian at Bayer, and he is confident the product is safe when used according to the label. It has been used for more than 50 years, and a lot has gone into pregnant cows. We do advise calling the mineral company to see where its concerns are. I think you would be fine using it, but I would like to know what the company has to say. Another option is a newer product, ClariFly, that is labeled as an aid for control of houseflies, horn flies, face flies and stable flies. I know it is offered in minerals and blocks, and as a premix. Keep up the integrated pest-management program. You are right on track.

Please contact your veterinarian with questions pertaining to the health of your herd. Every operation is unique, and the information in this column does not pertain to all situations. This is not intended as medical advice but is purely for informational purposes.

Write Dr. Ken McMillan at Ask The Vet, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email


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