My 3 Year Old Brindle Boxer Dog Pepper Has Started

My 3 year old brindle boxer dog Pepper has started losing hair on both sides of her. We took her to the vet and she has had a blood test and all is clear. Also a skin test has been done with no results of anything. The vet suggested it may be a hormonal thing. I am concerned as I would like to know whether a holiday kennel will let her stay there as they may think it is mang which it is not. It all started when I began to give her tinned dog food, I have since stopped this. I'm just very concerned as she had a beautiful coat in the beginning. She is playful, does eat even tho she's fussy, and normal apart from the hair loss. If you are able to suggest anything I can give her I would be very grateful. Cheers Naomi