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Dogs get cysts for no specific reason. Sometimes it is breed related (schnauzers, wheatons), but generally there is no known cause. I have had some success decreasing the occurence of the cysts by changing the diet to a lower fat, more easily digestible diet. If she is doing well on her diet now, then I would be a little reluctant to recommend changing it just because of these benign growths. Other issues can come up with diet changes that may be more of a concern.
Another option that may help is to add Vitamin E and 0mega-3 (fish oil) to her diet. This is easily accomplished with a daily supplement. It may help. There has been some evidence in the literature to support this.
Otherwise, you can just keep monitoring and removing as necessary (if the cyst gives her trouble).
Good luck and I hope this helps.