BLADDER PROBLEMS OF OLDER LIFE OR JUST LAZINESS?

We have a 8-9 year old chocolate lab who has all of a sudden started weeing and poohing in the house. he NEVER did this and it's come on all of a sudden. our female (4 years old) isn't doing it coz we leave them in kitchen and go to front room she follows and he doesn't when we come back there's a huge pooh or wee! they are left alone for a couple of hours a day but we've bombarded them with toys and just before take them for a walk and as soon as we come back for a walk then 1 in the evenings. overall they get about 3 hours walks sometimes and it's all of a sudden and only he's started doing it! (4 + sometimes hours.) please tell me weather he's being lazy or old age is starting to show or he's ill coz i'm soo worried about him! he seems fine during the day he just poohs. also our female seems to be getting bored of her toys that we've given her and just dumps them in our pond and goes after the rubbish bin and walls and anything else thats around! also she's suddenly put on weight after bieng spayed/nuetured why?