In this pic, I would say she is well overweight also. Do you have a more recent picture? I have never heard of a crest = founder. I agree with wee-foal -- get rid of or drastically reduce any grain if she's getting any and keep her working. If you're concerned about founder, keep an eye on her feet -- get to know her regular body controls -- heat at coronary band, digital pulse, regular pulse, colour of her gums, breathing rate. And keep her feet up to date.