I have been trying to avoid writing this post all day, I am very worried and scared but it doesn't make sense to keep it for myself so here I am.
Yesterday I took Bubu to the vet. He looks perfectly fine in behaviour and appetite, but in the last two months he had loose poo and that worried me.
It's not always loose; it varies from day to day and it definitely is not diarrhea. It's more of excessive liquid.

The vet saw the various poos on the bottom of the carrier and immediately said that it's not the poo itself but polyuria, which I suspected.
He listed a few things that could be the cause and none is good. He talked about kidney disease, liver disease, possible diabetes.

Because of the big bath he had the other day, I read he might have ingested water, so the vet will see us again in a few days and carry out blood tests and whatever other test he will need.

Apart from the first months of his life when he only accepted seeds, he has been a healthy eater for most of his life. He loves food and wolfs down whatever he can put his beak on.
This is bad sometimes because he is constantly begging and trying to steal the stuff from our plates; that's not a problem, usually, because of the diet I follow, very similar to his own, but he is mad about bread and cheese, and everything else we have in our plates. Even though we shoo him away he is always able to steal something. He recognizes cheese from the wrapping! He will lick the box thinking that he can reach it through the plastic! It's spooky.

Anyway obviously we will be more careful in the future about this, but I am afraid of the damage that's been done already.
The vet said that the most damage can come from fatty food, and that includes most seeds; I have no idea of how many seeds I should give Bubu daily, I usually put a spoonful in the bowl and let him eat as many as he likes. Should I reduce the amount?
I know that birds usually stop eating when they are full but he seems to be the exception.

Fortunately he is insured now, so I will be able to let the vet carry out any test that needs to be done, and I'd like to know your opinion and experience on what the vet should do the next time he will see Bubu.
I trust him but I want to be educated as much as I can on the issue so that I can discuss the matter with a bit of knowledge and maybe also suggest something if necessary.

And, while we wait for the tests, what type of diet he should be following?
The idea of losing him is not even thinkable, and I need to do EVERYTHING possible to make him better.

I think I would wait for a diagnosis before making any dramatic changes in the diet. Diet changes are stressful and you don't want to burden him with something that might not be necessary. If I remember right, your birds already eat a lot of vegetables but not pellets. So I would encourage them (but not force them) to start eating pellets, because the vet is probably going to want this anyway if it's anything diet-related. There's info on teaching new foods at http://www.littlefeatheredbuddies.com/i ... rsion.html

Here are a couple of links on polyuria:
http://www.petplace.com/birds/polyuria- ... page1.aspx
http://www.birdvet.com.au/exotics%20car ... lyuria.htm

One of them mentions heavy metal toxicity as a possible cause, and Bubu does like to steal things so maybe he's consumed more metal than he should. This is treatable, and if your birds aren't already eating it you could add some cilantro (aka coriander leaf or chinese parsley) to their diet. There is serious research indicating that cilantro might have chelating properties: http://europepmc.org/abstract/MED/86865 ... sGeIgkpc.8 All things in moderation of course.

I hope it turns out that there isn't a big problem!

Thank you Tielfan, tomorrow I am gonna read everything up.
It is amazing how many times this bird has been in trouble. Twice in hospital, then once he almost decapitated himself with one of the cage doors, another time it was a leg, once he ate so much millet spray that he had to throw up (it was the first time in his life that he tasted it, he was a baby), plus countless times when something really serious could have happened... He is the most mischievous living being on earth. The heavy metal theory is extremely possible, god knows the stuff he might have nicked and/or ingested when I wasn't looking.
I will buy them coriander more often, they all love it, fortunately.
Without making drastic changes for now, would it make any difference in the fat intake if I eliminate completely sunflower seeds from the seed mix? I have noticed that, after the hemp seeds, they are his favourites, he picks them one by one and leaves none for the other birds, the pig!

Sunflower and safflower seeds are higher in fat than the other seeds. They're also high in nutrition so you don't have to eliminate them completely, but it wouldn't be a bad idea to control the distribution so Bubu doesn't get so many lol.

Typical boy. I kept this one area all blocked off because it was very dirty, and guess where Beaker landed? He walked out covered in dust. He got a bath, then looked like Bubu.

Lol poor Beaker! But it's true, some of them seem to be in constant search for trouble. No matter how hard you try to keep them safe (and clean), they always find ways...

Before the vet visit I ordered some oat groats because they are great favourites. Now I am not sure I should offer them. Are they fat too? I hope not because I'd be able to steer him away from the fattier seeds with it.

From what I remember, oats aren't high in fat, but they give you energy, so Bubu may be bouncing off the walls.

OMG just what I need, hyper Bubu. But he loves those so much! All right, a moderate amount. He's like his mom, doesn't know what moderation is