First off, I want to apologize, because I might have to go into a little bit of detail about my dogs bathroom problems.
This morning, Royce had a normal poop. He seemed happy and energetic, like he always is. I fell asleep around 7:30 am and left him out, which is a habit we're trying to put him in and I woke up around 11:30ish. There were no accidents or anything, which I'm thrilled about, because he had gone 3 days without an accident in the house.
When I took him out around 3:00 pm today, he peed, then a few seconds later, had very explosive, liquidy diarrhea. He was still his normal self, so he didn't seem sick, then he stood by the door, wanting to go outside, about an hour after he went. I ignored him, since we were told by our vet, that the only way his bladder will grow, is if we don't let him out every hour. After 5 minutes of waiting by the door, he went in the house, and it was still explosive and liquidy. After his second go-around, we would immediately take him out when he walked to the door. He has gone about 6 times today and I'm concerned, because since we are putting him in his kennel soon for his (and our) bed time, he will wake up and immediately go in his kennel, which he has never done before. He is 4 months old, so he is still in his training phase, and I am worried that his kennel will be a complete mess, when he wakes up around 3 am, like he normally does. He always goes back to sleep when I put him back in his kennel, but not to sound selfish, but my wife and I like our sleep as well!
If he continues to have diarrhea tomorrow, we are thinking about calling our vet. Is that a good idea? We haven't changed his diet or haven't done anything differently, so it's just a concern we have, since this is his first diarrhea illness he's gone through.

Your vet told you to not let him out over hour so his bladder could grow? I have never heard of this. When either of my dogs waits by the door I let them out. Yes, sometimes they just want outside to play, but I will still let them out.

Did he have any different treats or anything? Maybe he got a hold of something he shouldn’t have? What you could do is take him off his food for a bit (12 hours or so), and give him a bland diet of rice and boiled chicken. Canned pumpkin (NOT pie filling) works wonders as well. So does cottage cheese or plain low-fat yogurt. Make sure he has plenty of water since it will dehydrate him. If he is acting normal, and it gets better within a few days then you should be fine. If he begins to be lethargic or if it lasts more than a few days then you should go to the vet.

I remember one time I gave Nikko one of those frosty paws frozen ice cream for dogs, and about 2 hours later it was explosive and was all over the place.

Also, he is going to have to go potty much more often until is gets better, and if you feed him rice he will pee more often too, since it has a high water content.

Not let him out when he has to go, so his bladder will grow? What a load of crock lol at least he sat by the door to let you know he had to go poo. Fast him for 24 hours to make sure everything has gone through his system Bland diet and plenty of fluids for a few days. If he still has the runs after that then I'd take him in.

I feel your pain. Our puppy had this for about three weeks. Sometimes it was like pure liquid! We had our vet test about three different samples of his poo and every time they told us that there was nothing wrong. We changed everything to natural because we thought he may have a sensitive tummy, food treats, everything! He would have to go so often we felt bad for the little guy. Whatever it was it worked itself out and now we don't understand how he can poop so BIG for such a little guy!!

I'd have your vet test it to make sure there is nothing wrong. If they say not then maybe wait it out a little.

And by the way, I have NEVER heard of the whole making him wait to go potty thing. It's a good thing he went to the backdoor when he had to go out!! I wish my older dogs would do that, they just start barking at me! At least the puppy is getting the idea to go to the back door now if he wants to go out!

Good luck!

Id agree with everything on here as I have struggled with the same thing in the past but it seems to have settled now. I would recommend a 24 hour fast and then a week of boiled rice and chicken. A lot of people on here recommend canned pumpkin (not pie filling) but I cant get hold of in the UK! Then ween slowly back onto the food that has previously agreed with the pup. I also found that swapping treats with carrots and boiling carrots in her food helped for fiber purposes!

make sure the puppy has plenty of water as the runs can cause dehydration.

If it persists and u are worried have your vet look at a stool sample. My vet was not concerned at all as my puppy was healthy, up to weight, not hydrated and not lethargic in any way.

I now have mine on sensitive puppy food and avoid any rich meats, she can only handle dry salmon or chicken food and not duck or lamb. It can be a bit of a trial and error finding suitable food.

I would also disagree to an extent about the bladder thing. A puppy waiting by the door sounds like a good puppy to me. Your lucky really with the runs that royce knows hes needs a poop!

never in my 40 plus years of dog ownership have I ever heard a vet tell you to make the dog wait so the bladder will grow???? This would make me seek out a new vet for sure.

If mine go to the door, out they go! Period. I hope he gets better!