Last November I had a 10 month old pup that had constant violent diahrea. I had a full spectum allergy test run. My vet drew a lot of blood and sent it off to AZ. She ended up having quite a lot of food allergies. It was $125 total and I got a really neat booklet personalized with exactly what she could and could not eat. It was really neat. I ended up getting her spayed and gave the booklet to her new pet owners.
alicat1, people can also be tested for allergies by drawing blood. My husband was tested this way years ago, and it's a lot easier and less painful than going to the doctor every few weeks to be repeatedly stuck with different needles One visit and you're done. . I don't see any reason why animals couldn't be tested the same way.