Firstly, re laminitis/founder, just because you've(or the horse) has done what you've always done/ate/lived on doesn't mean you'll get what you've always got. It usually takes people some time to develop type 2 diabetes from a junk food diet, and some people/horses are more sensitive than others. So do not at all rule out pasture, etc & I'd be treating her as laminitic. It may have appeared that she's had great feet until recently - & the weather would have affected her if wet for some time - but its more likely its been going on for some time but not at a level you have noticed until recently, or change in weather was the 'final straw'.
Mechanical founder to me means too much pressure on walls(eg working on hard surfaces with peripherally loaded hooves - 'road founder') causing laminar strain/failure. This doesn't look the case here, tho without more info & pics, little to go on. Home Katy Watts | Safergrass.org Mayfield Barehoof Care Centre Home Page
are some good places to start learning more.
If the 'WLD' is significant this does indeed need treating assertively & that may mean resecting, as if its deep, soaking wont get far enough up. You can't just leave wall infection to grow out, as it can eat away the hoof quicker than it can grow. I would not advise conventional shoes - peripheral loading for these feet, esp with the WLD, but *comfortable* support under the whole feet looks necessary. So I'd be going with padding &/or hoof boots.
I would be inclined to keep the horse on yielding - but dry footing, or otherwise padded/booted for comfort & sole protection, don't ride/work her until she's obviously comfortable(& use hoof boots). I'd keep her off rich grass/feed & on a low carb diet, at least until laminitis or any metabolic probs are absolutely ruled out, treat the WLD as aggressively as necessary, include a lami-safe good general nutritional supplement, pref with extra Mg, biotin & methionine, among the rest. And work on learning as much as you can about hooves & her problems.
In the meantime, more hoof & body pics with different angles - see in my signature for tips - more info on diet etc, will allow us to give you more specific opinions/ suggestions. Posted via Mobile Device