Guinea pig problems, perhaps constipation?

Question
QUESTION: I wonder if you can offer some advice, basically, my guinea pig Brownie, a male, about 11 months old, seemed lethargic yesterday and hasn't drunk at all from his bottle for about 36 hours, although I have been hydrating him by manually giving him water through a syringe. I don't think he has been pooing or urinating yesterday either, although today I have witnessed him producing really small poos (don't know about urinating, I think he may have though), his poo was nothing like the normal size he normally does, but all the same, I'm glad he's been. He's not as lethargic as he was yesterday and his appetite has definitely improved, I'm just waiting for him to get back to drinking from his bottle. It's weird that he's suddenly stopped drinking from his bottle because he's normally on it non-stop, he LOVES the sound! ;D Do you think it's possible that he could just have an upset stomach and will get better over time? He's definitely getting perkier as time goes on, we also gave him some olive oil earlier to encourage him to poo, because I noticed that the poos that he is producing are extremely hard. So yeah, what would you suggest? Thank you :)

ANSWER: I would check that water bottle spout and make sure it's not stuck so he can't get the water out of it. I've had that happen in my own pigs. Just tap the ball on the bottle and be sure there is water coming out when you do.

In place of water you can offer him frequent pieces of lettuce. That's excellent for hydration and is usually easy to get the pigs to eat. That will also take care of any constipation issue if there is one.

The hard poo may be from lack of water in his system. Lettuce and fruits will help replace that water that's necessary to make the bowel move easily. Hopefully within a day or so he will return to normal.

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QUESTION: Thank you for replying, unfortunately he's gotten a lot worse, I took him to the vet today and they gave him some injections to help him urinate and poo, but he has done neither for countless hours. He isn't holding any food or water down, simply just throwing it all back up, :( He's going back to the vet tomorrow but I'm not sure if he'll make it through the night. :( What do you think could be wrong with him? I'm thinking kidney / bowel failure?!?! ;'(

Answer
When a guinea pig gets stressed from illness, heat stroke, etc. they do quickly go into renal (kidney) failure. Dehydration will do the same thing to them, and since he's not been drinking that's probably what's going on. Poor little guy will most likely not suffer much longer and may have already passed away. I'm so sorry for the loss. There are some things that we just can't change no matter how hard we try, and this is one of them.