Years ago we got the advice to feed our dogs only dry dog food.
They're both over 15 years old now, and have never been sick once in all that time.
Yes, but once I did that too, years ago. At 15 years of age they both developed pancreaitis and died of it. The vet said it was from all the grease being sprayed on dry food. The best bet I guess is finding one of the dry foods that claims to be healthy.
What dry food? What breed? There is a lot that goes into the equation... you are actually very lucky when you read all the stories people post on dog health lists looking for help with their sick dogs. Many rescues have the worst problems because of their treatment prior to adoption.