Will changing my dog’s diet cause a food allergy?
Sometimes. If your dog’s new diet includes a food that she has been sensitized to—and there’s really no way of know—it could trigger and allergy. You might see symptoms like licking, scratching, head shaking, chronic ear infection, anal itching.
It is really not uncommon for a dog to be eating something for years and then seemingly work up an allergy to it. Allergies don’t just happen overnight. The dog needs to have been exposed to that food item for a very long time to create a buildup. Some even recommend rotating the diet every six months or so, but please remember to change the diet gradually, as any sudden one can create GI upsets.
You do need to know that it may not necessarily be a food that is causing the allergy, because there can be other factors that come into play, such as environment or even a predisposition. Some breeds are more allergy-prone than others.
The best thing to do is to determine if it is, indeed, a food allergy and there’s only one way to be sure it’s accurate: that is an elimination diet and challenge. Take the dog off all the foods it’s eating and we put him on a food that she’s never had before. Once the dog has improved, start reintroducing the old foods you suspect might caused the problems in the first place. If she has a reaction, which usually takes a few days to a few weeks, then you’ll know it’s a food allergy.
If you see no change, further investigation by a veterinarian is warranted—and a blood test alone isn’t an accurate test for any allergy. For instance, if your dog has developed chronic ear infections, the vet might take a sample of discharge from the ears to see if there’s a problem there. If it’s suspected that the allergies are caused by the environment, he or she might conduct a skin test.