why is our little boy doing this? it's so weird

[sotough]

I'm wondering if anyone can offer any advice on how to handle a weird toilet training problem. (Am also posting this under the potty training thread.)
Our DS (3.5) has been pretty much toilet trained for about nine months now. However, he hasn't totally cracked it, and are bemused about what is going on. Wees are no problem, but when it comes to poos, he is hopeless at heading to the toilet on his own initiative and routinely stains his pants with a bit of poo before getting to the loo.
we have learned the signs when he needs to poo, and hustle him off to sit on the loo, but he always denies he needs one, even if it's completely obvious to everyone including himself, and nine times out of ten, he stains his pants slightly before he/we can get him to the bathroom.
So basically every day, we are dealing with slightly stained pants, and we don't seem to be making any progress at all. this has been going on a good six months.
i have tried star charts (he's enthusiastic in principle; in practise, it's made no difference); we have been endlessly patient; and not got angry with him. He is very sweet every time it happens, saying sorry, etc, and that he'll "try again tomorrow" but i don't think he's actually trying to avoid it happening.
can anyone suggest any tactic for dealing with this? we are not sure if the problem is physical or psychological, though suspect it is largely that he's "too busy" to want to bother going to the loo for something that will take a while. he's an extremely energetic little boy.
any shared experiences/advice gratefully received.

Is he in any way regular or predictable. We found popping DD onto the loo at certain times and reading to her led to a poo and once she'd got the idea, it was fine.

You could also try upping his fibre intake, so he gets more practice and it's comfy when he does go.

Sometimes you can get something called 'encopresis' or overflow - where the bowel has stretched due to constipation and liquid poo from higher up the bowel seeps out round the more solid bits. See here.

Is he constipated do you think? I agree with upping fruit/veg (but not so much complex carbs like wholemeal bread as apparently these are more difficult to digest for little children) and fluid intake. You might also need lactulose or movicol from GP in the short term to try to get a more regular and soft bowel movement.

My dd did this for a phase too, and I think it was just because she couldn't be bothered to stop whatever she was doing, leave it til the last second, then realise she'd got to go up the stairs, etc etc and therefore had no time, and did it in her pants.
Sorry not particularly constructive because she did eventually stop doing it. She's 4.2 now and has been reliable for 6 months or so, apparently boys are a bit slower so hopefully it'll be soon.
Is there a more rewarding incentive you could use for while? My dd was a bit flippant with stars, however taking away a bedtime story or rewarding her (with jelly sweets, I know I know, I got desperate!! And it worked!) was more effective.
Best of luck endless poo stained pants is not fun iirc!!!

A LOT of boys do the poo with-holding thing at this age. If he isn't chronically constipated its very very likely to right itself very abruptly.

Agree with a lot of the comments about ruling out constipation but if he is genuinely just leaving it too late might it be a good idea temporarily do things to make it easier to get to the toilet when he "suddenly" HAS to go. Things that might help are: bare bum at home, leaving doors open/light on/seats up, potty in main room he play in so it's just yank pants down and sit, elastic waists so no buttons etc to deal with.

Any help?

thanks for all the replies - very reassuring that it's a problem others have experienced. I think it's probably a mixture of occasional constipation and being too busy with more interesting activities to bother getting himself to the loo.
one thing i'm wondering is whether it would be counter productive to get angry with him? i could try threatening him with no bedtime TV, which he would hate, and might be an effective "push" to get him to focus on stopping doing this; but am concerned that punishing him could really backfire and make him very distressed, so that going to the loo became an even greater source of anxiety for us all...

Could you say he could have an extra programme rather than a punishment iyswim?
Dangle that carrot!
Also make sure he drinks enough as my dd still gets this problem if she doesn't have enough water.