Our four-legged friends have become as much a part of the family as any human member, so it's understandable that we like to include them in the festivities. Many owners even admit feeding them a Christmas dinner. So what harm can it do? Well as it turns out, quite a lot. By giving into the desire to treat our pets with human food, we may well be putting their lives in danger. This may all sound a bit 'Bah humbug' but several ingredients in our annual turkey-stuffing ritual can actually do serious damage to pets.