It's not a pleasant subject but sooner or later your dog is going to experience an upset stomach and as a result, diaorrhea. More often than not an upset stomach and the odd bout of diarrhea is nothing to worry about. Dogs are scavengers and can and will eat some fairly disgusting things when given half the chance. Most upsets rectify themselves within 48 hours or so, during which time it is best to either starve your dog or provide a bland and binding alternative to their normal food, such as boiled rice and chicken. Charcoal biscuits are also known to help settle an upset stomach.
Sometimes however an upset stomach can indicate a more serious problem. If your dog has diaorrhea for more than a few days it is worth making a visit to the vet. In such cases you will normally be advised to feed a bland and regimented diet with minimal treats or chews.
Much like humans, too much of anything can cause a problem. Some commercial dog foods, particularly wet foods, can prove too rich for some dogs. If you find that your dog is not doing well on a wet food then it is worth trying a different brand or considering changing to a dry food. Many breeders have a favourite brand of food and many vet surgeries receive commission from selling the more 'high end' brands such as Hills, Iams and Science Plan. Just because you have a brand recommended to you does not mean that it is the only suitable option. Let your dog be your guide, if something doesn't suit him you will soon know and with so many types of food out there there is no reason not to feed your dog a diet that both you and your dog are happy with.
Many people feed their dogs rigid amounts at set meal times. This may not necessarily be the best option for you and your dog. Different breeds of dog have different needs both in terms of type and quantity of food. Puppies in particular need to eat a vitamin rich food several times a day. While some dogs do gorge themselves at every opportunity - most notably Labradors - there are plenty more dogs who benefit from free feeding. With this method you provide your dog with a bowl of food and allow them to work their way through it as and when they wish. Interestingly puppies who are free fed tend not to develop the habit of bolting their food or becoming food obsessed - both of which can have severe health implications.
All too often we see dogs who are fed a rigid amount and who as a result practically inhale their food. If as puppies they had been able to eat as much as they needed when they needed it is likely that they would not feel that any food on offer must be eaten as quickly as possible before it is gone.