I have a small herd of 11 cattle, none more than 1 1/2 years old. In the last 2 months. 4 of the calves (all 6 to 9 months old)have been getting raw patchs on their skin. The patchs bleed slightly then heal, the hair has not grown back. I thought they might be rubbing on something but that doesnt apear to be the case. My neigbor used to raise holsteins and thought the calves might have lice. The vet was out a few weeks ago so I had her deworm and delouce them with Ivomec+. Its been a month now and they are still getting sores. Any ideas what this might be and how to eliminate it?