Ask the Vet

Skin Conditions Tough to Diagnose

In young calves skin conditions are often secondary to scours. (Progressive Farmer image by Victoria G. Myers)

Question: We have a cow/calf operation, with one group of cows calving in the fall and the other in the spring, allowing us to use one bull. For the past four years, in the fall-calving herd, we have consistently found 1- or 2-week-old calves with a skin condition that resembles mange. One particular cow's calves have had the condition three of the past four years. It generally begins around the tail and progresses down the back line and the sides. All the hair comes off, and the exposed skin is raw-looking and bleeding in spots. The calf continues to nurse and does not exhibit any symptoms of distress or pain. What are your thoughts as to the cause of this problem?

Answer: A lot of the skin problems we see in young calves are secondary to scours. The loose stool can cause a moist infection that can spread rapidly. Flies will often lay eggs, and in short order, you have a problem with maggots. But, your description does not fit 100% with this condition.

I can tell you that we've seen a lot more dermatitis in cows and calves -- often caused by a hypersensitivity to insect bites. Photosensitization can also cause problems like the one you describe. This occurs when there is a substance in the skin that is reactive to sunlight. This can be due to something the calf or cow ate that contains the substance. It most commonly occurs when something damages the liver and impairs an animal's ability to process and excrete a substance derived from digestion of chlorophyll by microorganisms present in the gastrointestinal tract. White cattle or the white areas of cattle are most often affected.

In your herd's case, we also must consider the possibility of some genetic component since the problem occurred with calves from the same cow multiple times. Ultimately, a skin biopsy may be required to make a diagnosis.