Sounds like you could possibly be onto a good thing with this vet, sounds like she might know a thing or 2 about feet & that she was able to educate the farrier on how to trim better. Here's hoping!
I do have a few questions, considerations on what you've said tho...
(And it would explain the constant dish I see in her front feet - which I was beginning to worry it was founder). So my farrier did a 4 point trim, took her heels low, .... She said Summer was not hitting the ground heel first. She also told me it could be the root of all of Summer's problems. Her dragging her back foot, her falling, her strange gait at the canter.
Yes, stretched & chronically flared toes, esp with high heels is indeed indicative of disconnection of laminae between wall & foot, and 'rotated' P3 in relation to the dorsal wall, aka 'founder' or 'mechanical laminitis'. Did the vet suggest xrays to ascertain accurately exactly what's going on inside? I'm guessing that she was supposing it was due purely to bad mechanics, as you didn't mention anything about other factors of laminitis?
Yes, too often I hear chiro's & such lament the fact that if only the client had a good farrier to the horse before
they called for bodywork... Can be that 'upstairs' issues are behind hoof imbalance, but also commonly hoof probs which are causing the 'upstairs' probs.
If your horse hasn't been using her heels & they have been high & contracted, they may well be too weak to cope with being put suddenly into a support role. If the horse is uncomfortable, he will be landing toe first regardless how 'ideally' his feet may be trimmed. Therefore, with high, weak heeled horses, I tend to take heels down more gradually, &/or provide frog support padding where necessary, to aid *comfortable* frog/heel stimulation & therefore their development.
She also has slight seedy toe, which I will see what I can do for that. It's not severe enough to need any major work, but it's there and something I can help with immune 1, which she told me to keep Summer on, especially for how her feet are going to grow differently.
If it's not severe enough to warrant serious resecting, I imagine it was very shallow & the farrier was able to just trim it out? Perhaps it was all in the stretched part of the toe which was able to be removed? I don't know what immune 1 is, but I would still be treating the seedy area topically as well, for the next few days at least, in case the farrier wasn't able to get all the infection - it can be horribly insidious if not treated assertively.
The vet said that after a while, she wont even need shoes anymore, and if she does, she'll go up to a size 1 instead of being a size 0.
Sounds like a surprisingly huge change from trimming alone (assuming she didn't even have any bodywork?). And the above is certainly possible, but... I just would be cautious of 'rose coloured glasses'. If your horse has had run forward, contracted, high heels for a long time & is mature, while you should definitely expect improvement with good management, it may be impossible for her heels to grow wide & strong. Also, many horses, even with quite healthy feet to begin with, if diet, environment, nutrition, etc aren't conducive, will still need hoof protection/support in some situations at least. Re shoe size, obviously without seeing the feet... perhaps she is anticipating the feet becoming greatly wider, but esp if hooves are run forward & flared as you describe, I generally expect hoof size will become *smaller* not bigger, when they become healthy & tight.
Poor girl was sore afterwards, I tell you what.
Missed this bit in first reading, only seen it now after replying to rest. Unfortunately it makes sense of her different way of carrying herself immediately post trim. Why was she so sore? While depending on circumstances, it is (very rarely) unavoidable that the horse is indeed slightly more sensitive following a trim, through no fault of the farrier, it is something that is commonly due to farrier error - taking too much off for eg(tho sounds like he was instructed to do so by the vet so wouldn't blame him anyway). What did they say about this & what(aside from bute) did they give/advise to do about it?? If it's due to too much material being removed from her already weak feet, replacing some of the 'armour plating' by padding her feet until they grow thicker should do the trick, but I'm concerned with the possibility of high heels being dropped so much & suddenly that it is tendon strain which is causing the discomfort, which is something that's potentially very harmful. - Another reason why I tend to drop high heels gradually.
I'm sorry to play 'Devil's advocate' here but as Dr Bowker likes to say, it's not the unanswered questions that are the most dangerous, but the unquestioned answers!