The majority of the time it will come out t'other end without and issue. You know the drill if anything changes already.
The cod liver oil is an excellent idea from Tambo - what I would suggest though is: If you spot it coming out and it doesn't come out freely, don't be tempted to pull it as it might do some damage to the intestines (it will mean having a mucky cat for a bit, might have to keep him indoors until it's fully out so it doesn't get caught on the neighbours brambles)
All the best for you and Ziggy