Our rescue Lab has put on 6 kilos in the 9 months he has been with us! 
I know you'd expect him to or some on as he'd been a stray for a while but as he's about 10 and has arthritis in his back legs we don't want this to continue.
The DCs are terrible for always giving him treats and we've talked to them about this.
Apart from the blindingly obvious i.e. reducing his meal size and increasing his activity is there anything else we should be doing?