My old dog has fairly regular episodes of HGE or colitis (which is a different thing I know), last one was in June and he was down the emergency vets overnight. He has mucus in his poo again today with a bit of blood, and has thrown up in five places indoors! However, he is fairly his usual self and wants to eat. I dont change his diet and he is not a dog that picks up food when we are out, he sticks right by my leg so I can monitor him well. I cant pin down anything that could keep causing him problems, His jabs are up to date. He will go to the vet if no improvement or he goes downhill, but usually unless he is really ill its antibiotics and a hefty bill. are dogs prone to this sort of thing once theyve suffered?