Question about allergy "testing"

I have eliminated all foods with fish in them for Matilda. This is just a starting point to see if she is allergic to it, I just randomly decided to start with that and not chicken or turkey or something like that.

(This has to do with severe/chronic feline acne, to see if she either has a contact allergy to fish or a food allergy to it. The acne problem itself is a long story and not really the point of this thread).

So far she has gone a week eating only food that is fish-free and fish-oil free. How many weeks should I give it to see if it's helping or hurting or doing nothing? I was thinking 3-4 weeks.

In my experience when a certain food ingredient is causing an allergic reaction, eliminating that ingredient will lead to noticeable improvement within 24 hours. After that, as long as you stay away from it, there is continued improvement every day.
So if you eliminate a certain food ingredient and you donâ€[emoji]8482[/emoji]t see any improvement whatsoever after several days, then you can safely assume it wasnâ€[emoji]8482[/emoji]t the ingredient causing the problem youâ€[emoji]8482[/emoji]re trying to fix.

Have I ever given you the list of food ingredients that most often cause allergic reactions? I canâ€[emoji]8482[/emoji]t remember, so here it is now:

Beef and beef by-products
Brewerâ€[emoji]8482[/emoji]s Yeast
Corn and corn oil
Pork
Turkey
Eggs
Milk
Fish and fish oils
Wheat
Soybeans
Chicken

Many cats and dogs are also allergic to rice and other grains not mentioned in the list.
Then there is cellulose, which usually causes digestive problems.

If the experiment youâ€[emoji]8482[/emoji]re doing now doesnâ€[emoji]8482[/emoji]t produce any improvement and you want to keep checking for allergy, then your next step should be a food trial with a canned single protein food, preferably with a protein source Matilda hasnâ€[emoji]8482[/emoji]t had before. It should also contain a carbohydrate source thatâ€[emoji]8482[/emoji]s new to her. The good thing is that these foods donâ€[emoji]8482[/emoji]t contain any grains, brewerâ€[emoji]8482[/emoji]s yeast, etc, so you easily eliminate a whole bunch of allergens without even trying. You can also buy single protein foods that contain the usual protein sources plus some vegetables, but again, no grains. There are lots of choices and if food has anything to do with Matildaâ€[emoji]8482[/emoji]s problem, sooner or later you will find the food that brings improvement.

Iâ€[emoji]8482[/emoji]d like to recommend you a great book with lots and lots of incredible information:
Pet Allergies – Remedies for an Epidemic by Alfred Plechner, DVM

On page 99 Dr. Plechner mentions that 7 days is enough time for a hypoallergenic diet to start working.

I can't think of anything else at the moment except that be sure not to use stainless steel for food and water. Use only glass or corelle. They are the safest, neither can cause any skin reactions.

THAT is not a real accurate list today...

CATS

Fish ( oil techinically is not a allergen thou in some it is due to poor refining)

wheat

soy

peas
COMING up more and more

chicken

beet pulp

potato

Yeast

ceramic CAN and OFTEN causes allergies do to glazes ... ie why Stainless is so popular

Many of those listed by Violet ARE MORE common is DOGS...

HYPO = less ... to date on Science diet in a dog formula has made a NON allergy food