Methocarbamol is just the generic name for Robaxin. It’s still a “human” drug that can be prescribed for horses.
Quick update: I think she hasn’t been drinking enough!
I was ready to poo-pooh the hydration suggestion due to the fact that she has a heated waterer, has had slightly loose stool (not hard, dry, or infrequent), goes through salt licks pretty quickly, and has had tons of gut noises, but I’ll be darned if we haven’t had consistently great rides since I added a shallow scoop of electrolytes to her daily alfalfa pellet mash. Warm days, cold days - she’s been her usual forward, strong-backed self and responsive to my seat again. We’ll see if it lasts when the next long cold spell hits… We’ve had some very cold days, but not prolonged spells where the highs are close to 0F.
Vet follow-up found zero lameness or back pain, and she thought kissing spine was unlikely and did not think I should go to the clinic for imaging unless we can’t otherwise solve it. Blood levels for whatever is in a standard blood chemistry test (plus E and Se by request) were all normal, except for low protein/albumin. That plus lots of loud gut noises in all quadrants made the vet think that we’re still dealing with GI upset. Continuing gastrogard was recommended, but I’m not sure we can be so sure this is all gastric and not intestinal, especially given the “intestinal hypermotility” to quote vet, so I’m finishing up an extra week of GG and will try to wean off extremely slowly to prevent acid rebound. My vet was pretty wishy washy about whether any treatment was advisable for intestinal upset, so I’m unsure how to proceed on that front.
In any case I figured while waiting for vet appt that it couldn’t hurt to try electrolytes given how difficult it is to monitor water in our boarding barn set up. She hasn’t done any of the weird under saddle pre-poop behavior since the ride before I started it. And she hasn’t been protecting her back or blowing through my seat either. I’ve kept the E in her supplements but haven’t been very good about the heating pad (need it for my own achy body now that my horse is moving big through get back again).
I’m optimistic. Will update if anything changes…
Good for you! Here’s hoping you’ve found the root of the problem. 
[QUOTE=GiantSteps;9011189]
I added a shallow scoop of electrolytes to her daily alfalfa pellet mash.[/QUOTE]
Just an FYI - my vet and I discussed daily electrolytes after a colic and he said it’s known they can be hard on the stomach, especially for a horse that leans towards ulcers.
So I do a tablespoon of iodized table salt daily in the feed and a pile of loose salt available on the stall feeder lip. I’ll add electrolytes when we have extreme temperature swings or extreme heat or cold.
So if she stabilizes on the electrolytes, consider trying just salt for a bit. You can always add the electrolytes back in if it doesn’t go well.
Supplement Magnesium and possibly B-1 :yes:
If that doesn’t help, I’d let her relax and stretch on the lunge before getting on, and warm up/ride with a quarter sheet.
