Since I have also read your other post in re easy keeper/overweight, I am wondering if a total diet evaluation night be prudent.
“Easy keeper”… I hate that term : D They are maybe CHEAP to keep but when we cannot seem to feed anything more than air yet the horses is heavy, how do we achieve the right nutrient load and how do we know when we have? Easy keeper, indeed… not..
Where your mare seems to ‘survive’ well on pasture perhaps there is still something missing in her diet/ her graze components. The overweight can definitely be a low key metabolism and can also be a mineral or vitamin deficiency, ‘specially where she is currently sporting dry itchy skin and thin hair(mane /tail). What do her feet look like? Might consider an absorption issue if her pasture is healthy and she is getting what she needs..is her manure “normal”?
I know this concept can be easily overdone but diet: ratios of vitamins, minerals and all the good stuff in proper amounts along with regular and diverse exercise are the basics of any healthy weight. Just from curiosity, look into what grasses are in her pasture. Possibly there could be one inocuous weed/plant that she has munched and is maybe experiencing a mild allergic reaction. OR there could just be too much of one plant, not enough or another. The soil itself can also yield (or not: in New England, necessary Selenium is much lower in the dirt than required amounts so it is commonly added to many of our grain products as well as available in supplements) certain nutrients to what grows in it.
Due to the possibility that her nutrient base is out of whack (volume is NOT the answer: components/ingredients ARE), a chat with a nutritionist or veterinarian could shed some light for you.
Easy keepers vs the hard ones…. At least with the hard keepers, we KNOW they are getting enough of everything…. and then some.
Chat with your vet.
Ride more (if you can) : )
Sure there's right and wrong but mostly there's just a whole lotta different.