Written By John Burns BVMS MRCVS
If a dog or cat is reacting to something in their diet, it is important to look at their dietary history. This is often very difficult as many pet food labels do not state specific named ingredients. For example the ingredient ‘meat’ does not indicate to the owner what species their pet has been eating. It could be lamb, beef or even rabbit for instance.
It is recommended that an animal fed an elimination diet is given a novel protein or carbohydrate source. This is an unusual ingredient that they have never eaten before so won’t have had chance to build up a reaction to the ingredient. Duck, pork and egg are examples of novel protein sources and potato or maize are examples of a novel carbohydrate source.
All other foods, treats, table scraps and tit-bits must be eliminated from the dog or cats diet. Pets can either be fed on home cooked elimination diets such as fish and potato or chicken and rice or commercial diets can be used. If using a commercial pet food it is important to choose one with a single protein source (this means that it only contains one meat source rather than several meat ingredients).
The ingredient list should be short with as few ingredients as possible. All the ingredients in the list should be named i.e. avoid diets which state they contain ‘cereals’ and ‘animal meat’.
The elimination diet should be followed for 8-12 weeks. After this time, you can “challenge” the dog with some different ingredients one at a time to see if they react.
If you have seen improvements, you can then start to reintroduce other food items one at a time in order to determine what the animal is reacting to. Experts recommend that each new food must be introduced two weeks apart as some reactions to ingredients may be delayed.
You can continue to feed the new diet long term as long as it is a complete diet and suits the pet’s nutritional needs. Rotational feeding is also sometimes recommended for dogs who are prone to developing reactions. If you can find 2 or 3 diets that the pet does well and rotate between them it helps to reduce the likelihood of them developing another reaction.
If there are no improvements after 6-8 weeks on an elimination diet then this could be for several reasons.
(1) the pet parent did not follow the diet and gave their pet other food or treats
(3) the dog or cat is actually intolerant to one of the ingredients in the elimination diet
(4) the dog or cat is suffering from factors other than food intolerance
You may need to discuss the new diet with other members of the family to ensure they are all on board. A different diet may be tried with some new ingredients that are different to the previous feeding trial to narrow things down further. We may also need to look at environmental factors such as pollens or cleaning products.
Unfortunately, top specialists no longer recommend carrying our allergy tests in pets as they are extremely unreliable. Scientific comparisons have been done with healthy dogs showing they would still come back with positive results even if they were having no reactions to food.
If a dog has never eaten an ingredient they cannot be allergic to it, so this would be a false positive.
Unfortunately, on the nutrition helpline, we speak to lots of owners who are very worried following their pet’s allergy test results but we say to only use them as a guide as many of the results are likely to be false positives. Carrying out an elimination trial is the gold standard when finding out what your pet is reacting to.