I can only report on my single experience. My female Rottweiler, Story, was having constant hot spots some years ago, which as you probably know are caused by itching in a single area until the skin is broken. Bacteria invade, and the whole thing turns into a nasty mess. It was to the point I'd barely get one starting to clear up when another would appear. She once had three at the same time. A woman I trained with mentioned allergies. She had allergic dogs and had them tested via blood testing. She said her experience with testing at the university in our state, the place most of us would probably turn to, was not encouraging. Results from testing the dogs this year and then a few years later often had little in common, but you'd expect the allergies from the first test to still be there even if new ones appeared. She recommended:
Home - Spectrum Veterinary
My vet had never done this before, but he downloaded the instructions on the website, drew the blood, and sent it off. I received a pretty comprehensive report. Although it didn't include every single thing you can imagine, it did cover many possible environmental allergies and most of the ingredients you'd find in available dog foods. There wasn't much I could do about the environmental things other than wipe her off after she'd been out (hers were all grasses, trees, and the like, not thank goodness, things like household dust). I did adjust her diet to avoid every ingredient she showed a reaction to, which in the end led to a raw diet. Her problem isn't meats but everything else in dog food - wheat, corn, rice, potatoes, peas, even some supplements like alfalfa.
Story has gone from constant hot spots to one or two a year. Her ears, which had never been infected but were always pretty gunky even when cleaned weekly, are now to where I only clean them occasionally and they're not much worse than any other dog I've had. Her eyes, which were always runny didn't clear up, but they're better than they were.
Every once in a while I'm reminded of the problem. For instance, I read all the hype about coconut oil and starting adding some to Story's diet. Itching! Whoops! Incidents like that are indentifiable and controllable so long as you never add more than one new thing at a time.
The weakness in the report I received was the included recommendations. Whether, like me, they simply couldn't find a dog food without ingredients the test showed sensitivity to and so settled for recommendations of foods that only had a couple of things on her list or whether their recommendation procedure is always flawed I don't know, but they recommended kibbles that had ingredients Story's test showed were a problem. Before going to raw, I did find a limited ingredient kibble that only had one thing on Story's list - alfalfa, which is a supplement and wouldn't be present in quantity. Feeding that did reduce the hot spot incidence, but her coat turned dull, and that's when I went to raw.
So for me the test was really worth it, but that is, of course, just one person's experience. I'm sure the elimination diet thing works if done carefully, but I knew I didn't have the patience and how exactly do you feed just one ingredient that's in kibble in the same form it's in when cooked into kibble? Good luck with your research. I hope you find a solution for your dog.