Unfortunately we've been programmed by the vet and food industries to think EVERYTHING is an "allergy".
I know I've talked about this before, but the Chinese/Oriental way of thinking is that some foods are merely "inflammatory". Meaning -- sometimes they are ok, but sometimes IF the body is in a perod of imbalance, or **at certain times of the year** then some foods may cause inflammation.
Food allergies are almost NEVER EVER ***PRIMARY***. Yes -- food allergies are real -- but they are typically **behind** atopic allergies in cause.
Now -- don't have a hissy fit yet -- most of the time people don't KNOW their dogs have atopic allergies because they are so busy food-switching to find something to "fix" the problem that they miss the fact that certain allergens may be present **all the time** in the dog's environment that simply keep the dog CLOSE to the edge of allergic reaction.
Think of it this way --
Take a bucket -- and make a small hole in the bottom. Sit that bucket under a faucet that is running ... a little.
First off -- depending on how big the hole in the bottom is ... and how fast the tap drips -- it may be a long time before that bucket fills. In the summer when it's hot either the tap may run faster or slower or evaporation happens quicker. But it might vary.
But eventually if the water going in is faster than the water dripping out that bucket is gonna fill up.
And MAYBE someone dumps a cup of water IN that bucket just about the time it's ready to over flow.
Let's call the dripping water allergens (and the hole in the bottom is the immune system trying to keep up WITH the allergies). Let's say that last cup of water is a "food change" -- if the last cup of water made it all overflow -- was it the "fault" of the last cup of water?
No -- the danged bucket got full just of normal daily "atopic" allergies. But you SAW the effect of that last cup of water that went in.
So -- you switch foods again and ... maybe that calmed things down. (or maybe you did allergy meds or anti-inflammatories which reduced the level of water generally in the bucket).
But -- at this point now you've got a mostly full bucket of water -- and it LOOKS like when you switch foods you stop the problem. But really you don't -- because the atopic allergies are still there keeping the bucket FULL. And at certain times of the year -- or when it's dry in the house and the mold from a basement or dust mites from wallpaper or general dryness from heated air -- sometimes of the year those things are worse than other times of the year. so maybe you go for a long while on this new food when the atopic allergens aren't super bad -- but you *think* it's food that's helping. But suddenly a few months into that bad WHAM -- you get a reaction.
It's **probably** that the outside conditions changed and raised the allergy level -- OR the dog's body changed with age and made it more prone to a certain allergic sensitivity -- so a lot of times people keep chasing food, not realizing that they're actually trying to compensate for what's going on in the air around the dog NOT *just* that food change.
But this is why suddenly a food can create a problem -- not because Poochie is truly "allergic" to it -- but simply that it's an inflammatory all along and at THIS time of the year/season Poochie is more prone to **being inflamed** so it bothers more now than at other times.
Chicken (at least according to the Oriental school of thought) is an inflammatory meat. I have one (Billy) who could get inflamed just *thinking* about it. He NEVER gets chicken other than as a treat. I also never give him rice -- it will take a simple predisposition to being inflamed and blow him out big time.
It's NOT an allergy. It simply is a catalyst for something to happen.
I hope that kind of explains why things can change so fast. The immune system is the deciding factor in allergies. But the problem is the immune system should go "on" when presented with a threat. THEN it should go "off". But ... partly because of environmental toxins, and partly because we've ushered in a world where allergies are huge (both with dogs AND humans) it's so easy for the immune system to just continue to inflame.
Inflammation is the body's defense -- it's trying to get rid of toxins and it's reacting to what's inside.
The other thing I'd strongly suggest is bloodwork be done pretty regularly (like 2-4 times a year) -- because if the body is reacting to toxins and the liver values get skewed even a *little* you can see HUGE changes in the skin (and what's more you won't get resolution if you're trying to treat those skin problems).
If you want to learn more about the Oriental way of dealing with diet and these sorts of problems I'd suggest http://www.tcvm.com -- there's a locator on the left that could help you find a practitioner near you.
OR -- you might want to check out "Four Paws Five Directions" by Dr. Cheryl Schwartz -- she's a TCVM vet and it's the handbook. Lots in there about food and the impact it has on the body.
Other things too -- even the time of day a dog reacts to something can be tied to it's cycle. Sounds strange but it's true - I've seen it with my own eyes.
I went with 2lr2Meg (Pirate's Mom) when Pirate was examined by Dr. Xie last year when he was having seizure issues (and Pirate is Mr. Major Food Issues too). One of Dr. Xie's questions to Meg was "Does Pirate tend to seize oh ... maybe between 11: p.m. and 2:a.m.??
You could have knocked her over with a feather because those were EXACTLY the hours Pirate would seize. Turns out the body clock has a whole lot to do with those kinds of issues.
Works in the food realm too -- because certain parts of the body work better at certain hours so something ingested at a sensitive time of the day can cause a problem darned quickly.