Can a dog suddenly develop an allergy to food he has eaten for years?

My dog suddenly developed swelling. First it was on the bottom of one jaw. I made an appointment for the vet but the swelling disappeared and then reapeard a day later, then disappeared. Tonight the swelling is on his nose as well as his lower jaw. Please help.

Get the dog into the vet whether there is swelling going on or not. This might be something other then allergies and they can run tests to find out. However, allergies can simply develop as they sometimes do with people. It is not all that uncommon. But i would definatly have the vet give you the final word on that. Also depending on where your from, it could be such things as bee stings.

Are there insects that could be doing this? Does your dog have red gumline, perhaps infections in his mouth/teeth/jaw?It could be an infection or something.As far as dog foods go, it sounds like an unusual reaction. What does your dog eat? If it has wheat and corn and/or multiple meat sources or cereals and unidentified "meat" products, it could be food. But it sounds like something else is going on. Take photos of the swelling and take the dog to the Vet even if the swelling has disappeared. They can tell a lot by running some blood tests and doing an exam even when there is no visible swelling.Also, what plants are in your yard or house?There was a plant, one place I lived that had these very tiny thorns that embedded in animals or people that barely brushed against it. You couldn't see the thorns like you can on roses- they were tiny like needle heads. It really hurt one of my dogs and we were confused until we found the plant and went to the Vet.so hope you find out the cause and can get the Vet to do some tests. Here's a site that may be of interest to you, regardless of whether related to any swelling, it is about diet concerns:http://www.accessdata.fda.gov/scripts/petfoodrecall/Many people don't realize how many pet foods have had batches recalled, multiple times! This list, you'll notice, was updated in Jan 08

they changed formila in dog foods all the time maybe this time they put somethin in this batch ur dog just is allergic too change brands and get ur pet to the vet asap to see wht ur pet is exactly illergic too!

Yes, it's usually after eating the same food for years that dogs do develop allergies. With food allergies it's the paws, legs, underbelly, ears, face, anus, the area is hot to the touch, the dog is itchy and ends up non stop scratching/chewing. Swelling is something else and needs to be vet checked. Good luck.