8 year old soiling

[DingbatsFur]

Hi,
I am at my wit's end with my 8 year old. We have had issues off and on since he was toilet trained about how when he is very interested in something, he doesn't go to the toilet. As a 3 year old he would cheerfully turn out a perfectly formed poo in his pants rather than stop playing with his trains.
Now at 8 if he is playing a game, chatting with a friend or watching a squirrel he basically holds it in rather than going and ends up with skid marks, often with poo stuck to then.
When we suggest to him subtly and the unsubtly that perhaps something has happened which requires him to change he denies all knowledge. I often find myself taking him off to the toilet to get him to remove the soiled pants.
I thoughy at first he was constipated, but he has no tummy pain or any other symptoms.
He claims he can't feel it, but he also claimed this with night time bed wetting and then stopped the day after he was taken to a hospital consultant (as I was very alarmed when he said he couldn't feel anything).
Although I wonder if there is a medical issue, I really think he just can't be arsed.
Incidents happen at home more than at school an there is always a toilet free here.

While only you can say if you think your child is just too lazy, I can relay an example which might have some relevance.

The parent in question had the same set of circumstances but with a slightly older child. They took them to the doctors, who referred them to a consultant. It was suggested that a procedure could be done to ascertain if there was sensation in the child's back passage, potentially followed by surgery on the sphincter muscle. The child, who found this course of action to be undesirable, magically found the ability to use the toilet at appropriate times, problem solved.

Thanks Flossiemummy, I shall try that.
If he recurring issues I would be more concerned, but it seems if he can be bothered then he's fine.
Lovely boy otherwise!