Elsewhere on this site we’ve published the evidence for which foods dogs and cats are allergic to. Now we’ll show you how to figure it out for your own pet. This even works for a mouse!
You might also like: The myths about food allergy in dogs.
Diagnosis of Food Allergies
The bad news is that there is no simple test. Popular IgG and IgE test kits sold online are not reliable.
The good news is that you can do it at home. It’s called an elimination diet. You have two choices:
- Buy one off-the-shelf
- Make it yourself (this is preferred if possible, see below)
Commercial Elimination Diets
In Australia, both Hills Pet Nutrition and Royal Canin sell elimination diets.
Food Allergy Diets for Dogs
- Hill’s Prescription Diet d/d Potato & Venison Formula – canned & dry
- Hill’s Prescription Diet z/d – dry
- Royal Canin Hypoallergenic – canned & dry
- Royal Canin Anallergenic – dry (our preference)
Food Allergy Diets for Cats
- Hill’s Prescription Diet d/d Venison & Green Pea Formula – dry
- Hill’s Prescription Diet z/d – canned & dry
- Royal Canin Hypoallergenic – dry
- Royal Canin Anallergenic – dry (our preference)
- Royal Canin Gastrointestinal (pouches- this isn’t truly an elimination diet but I’ve included it as it works well for many cases of IBD)
Home-Made Elimination Diets
The home-prepared diet is considered the gold standard elimination diet. Although commercial alternatives from your vet are easier, we always recommend at least starting by trying to do it yourself. Here’s how you do it…
Step 1: Understand the theory
This is a giant test to see if your dog or cat is allergic to part of their existing diet. Therefore, if we design a diet with NO previously used ingredients there should be no reaction. You can’t be allergic to something your body has never encountered.
You have to make a simple diet entirely out of ingredients your dog or cat has never eaten. Your diet won’t be balanced but if your pet is adult, in good health and not pregnant, no harm should occur.
Step 2: Make the diet
For dogs, choose one meat and one carbohydrate source in roughly equal quantities. Ingredients might include one of: goat, camel, rabbit, kangaroo, unusual fish species, duck, plus one of: pumpkin, sweet potato, potato, tapioca, etc. By all means, cook it in batches to save time.
For cats, just choose one meat source from the above list and there’s no need to cook. It’s a lot easier. However, never buy ‘pet grade’ meats if they are fed alone, only use meats fit for human consumption. Read why here.
Step 3: Never, never compromise
This is the critical thing: the immune system is the most sensitive detector we know. It can’t be fooled. There’s no point in doing an elimination diet until every member of the household is on the same team.
If you give any other food item, even tiny scraps or flavourings, you could ruin the test. You should place your pet where they can’t hoover up table scraps or kitchen waste,. Never leave food where they might have access, including that of other pets.
It’s worth also asking about the food source. The meat will need to be 100% pure, with no other other meat packed on the same equipment without cleaning.
Step 4: Run test for 8 weeks
After feeding it for 8 weeks, over 90% of food-allergic dogs and cats will have improved. By this time, if your pet is still itchy or unwell, the cause is unlikely to be a food. If they are getting better, you still have more to do…
Step 5: Rechallenge the original diet
This is the real test; do they get itchy again when they start eating the old food? Otherwise the improvement might have been due to something else. If you get a worsening of itch after rechallenge, your pet most likely has a food allergy. The next step is to find out to what…
Step 6: Identify the allergen(s)
Put them back on the elimination diet until they are better again. Now, a week at a time, add back one individual ingredient (such as beef, chicken, wheat, dairy) until your pet starts reacting to one of them. There could be more than one.
Step 7: Design a lifelong diet
Once you know the offending ingredient, the problem is usually that it will be found in all pet foods at some level. However, you can choose special veterinary diets, high quality limited ingredient diets, or just decide to make your pet’s food yourself.
Remember, elimination diets aren’t balanced enough to use beyond 8 weeks. You need to either find a commercial alternative that is tolerated or get nutritional advice on how to construct a balanced diet.
If you got this far, well done; you’re on the home stretch now.
If your diet trial failed, don’t despair. It’s probably not the food but there’s so much more your vet can do.
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