Glad he’s doing better!!! I have had buns had some sort of “gas attack” where they refuse everything but then perk up an hour later. I would have done exactly as you did: critical care and a tummy rub. Sometimes I think the critical care alone is enough to keep things moving!
And I agree dehydration could have been at play. I have been learning more and more recently about the importance of hydration in keeping the gut moving well, and how it can set off a cascade of slow down and even nausea (even though buns can’t vomit). So critical care definitely helps, and giving a little water never hurts either. Have you ever done the “skin tenting” test to check for dehydration? You basically grab a handful of scruff, and then see how it snaps back. If it kind of slowly rolls back into place, bun is dehydrated.
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.