Sorry about the length of this post, but I wanted to cover any relevant info that I could. - We have a 4 year old calico longhair that has had a oily tail base for awhile. It has never caused a serious problem until recently where she has stared grooming it excessively. Her hair is starting to fall out and none of our treatments are working well. we've taken her to 2 vets and both were unsure, but thought it may be due to food allergies even though we feed her a high quality food. They prescribed shampoo and we bathe her as often as we can, but it will only work for about a week before her coat will become oily again. After some research, i wondering if it could be caused by a malassezia infection. Awhile ago, we used to bathe her in olive oil to moisten and soften her skin and coat, which was near the time her symptoms showed up. We thought her seborrhea was due to food allergies, but because yeast bacteria is lipid dependent and thrives on substances like olive oil, we were wondering if a Malassezia infection could have started and caused her to itch. She also has some feline acne which may be a related symptom ( but we do not use any plastic bowls anymore). Any information or suggestions would be greatly appreciated!!