Bear (7 months) always gets loose if he has eaten something new or something he's picked up on a walk that he shouldn't have....
Most of the time he's absolutely fine in himself and it sorts itself out and gets back to normal within 24 hours or so. But we've had a couple of times when he hasn't bounced back and instead has got dehydrated, tired and listless - then he's needed to go to the vet from some medication and special food.
I'd keep a really close eye on them and if it goes on longer than 24/48 hours, they stop drinking or they start to seem unwell and then I'd check with your vet asap. I was surprised just how quickly Bear seemed to go downhill when he got ill - but thankfully he bounced back just as quickly once the vet had given him some medicine. Puppies can be such a worry!
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