Delicate tum

As my collie has got older, I've noticed that she has developed an increasingly delicate stomach. The slightest thing can set her off. I used to be able to give her some of our dinner or little treats, but now there's usually a smelly consequence the next day.
Even something a simple as an overnight stay at a hotel can mean that she has an upset tum overnight (which is hard to cope with!). It could be the change in the water or just the stress of a change of routine.
Is there anything I can do to help her digestive system run a little more smoothly? Or is this just something that happens with older dogs?
Carol Wilby, Waltham-On-Thames

Although my Lab has an cast-iron constitution, I do tend to play it safe and feed her only her dog food, day in, day out. I suppose it is because professionally I have seen so many stomach upsets in dogs after a change in diet, such as eating titbits or scavenging. From my side of the consulting table, such problems are best avoided from happening in the first place by sticking to a stable diet. So, the easy answer is to stick to what you know agrees with your dog’s digestive system. Really, it is much like the situation with ourselves – if you know that you have a stomach upset after eating a particular food, then you avoid it, and curse when you are ill after forgetting or risking it!
A change in the water does seem to be a common cause of an upset stomach, although one cannot rule out ‘stress’ since the water may have changed because of going away to a different place. Stress is hard to quantify and is not simply an unpleasant experience. Stress in this instance could really being used to describe a challenge for the gut, a change in the intestinal environment.
On that basis, pre- and pro-biotics may be worth giving to your dog when you know a change in the water is likely, such as when you go away. Alternatively, you could give her bottled water to drink at home and if it does not cause a stomach upset then try using that as her sole water source when you are away. I must admit that I do not hold with bottled water - I drink tap water – but this may well help your dog.
Alison Logan, Vet