Dog - Food Allergy

What are allergies and how do they affect dogs?

Allergic reactions are very common in dogs and are fully described in a separate handout on Allergies and Hypersensitivities.

Is there more than one type of allergy?

Yes, there are at least five common types of allergy in the dog:

1. flea
2. food
3. contact
4. inhalant (atopy)
5. bacterial hypersensitivity

What is food allergy?

Although it is well known that people can be allergic to certain foods, (e.g. strawberries, nuts, etc.) it is only relatively recently that food allergies have come to be routinely diagnosed in dogs.

What are the signs?

The main signs are pruritus (itchy skin) and an upset bowel. Just as in children, other more subtle signs also occur. In dogs these include hyperactivity, weight loss, lack of energy and aggression.

My dog seems to scratch a lot but only periodically and at the same time have a loose bowel. Is this a food allergy?

Many dogs will occasionally react to something they have eaten. This may be due to a sensitivity to a particular type of food. The symptoms are often not a true allergy but just a mild stomach upset. Once you have associated the upset with that particular food and avoid feeding it in future, the problem is usually satisfactorily solved.

Food allergy is similar but can be thought of as more profound. Antibodies are produced against some constituent of the food. In an allergic animal the immune system overreacts and produces antibodies to other substances which are normally tolerated in the body.

Are some ingredients likely to cause allergies more than others?

The most common food allergies in dogs are dairy products, beef and gluten (from wheat) but any dietary protein may cause an allergic reaction. Skin irritation can also occur. Dogs with a severe allergic response may show both skin and bowel problems together.

Are these the only food constituents likely to cause food hypersensitivity?

No, virtually any food or food ingredient can produce an allergy. Proteins are the most common cause but other substances can also be responsible. As with children, food additives are sometimes found to be responsible.

How is the condition diagnosed?

Until relatively recently feeding an elimination diet was the only means of determining the presence of a food allergy. This is a diet chosen which contains none of the ingredients of the previous diet. This is fed for a minimum of 4-6 weeks. If the clinical signs improve on the new diet, one meal of the old diet is fed to see if the clinical signs return. The problem is that since the elimination diet may not be as palatable as the original diet, there is always the possibility that your pet sabotages your best efforts. Just one mouthful of say, beef, could undo weeks of feeding the special diet! If you have other pets in the house eating "normal" food this can easily happen.

Today there are blood tests available which will give a relatively accurate indication of whether the dog is allergic to constituents in his diet.

How is the condition treated?

Once the offending constituents have been identified, a diet is organised that does not contain these particular substances. Originally one had to make one’s own diet, for example chicken and rice was a popular choice for dogs with beef protein allergies. Today there are a number of commercial diets available which are palatable, hypoallergenic and on which the dog can be fed indefinitely.

Occasionally commercial diets containing the appropriate constituents may not be available or alternatively your dog may not eat the commercial diet, in which case you may be forced to prepare a home cooked diet. We will be happy to advise you.

Can the problem be cured?

Unfortunately at present it is not possible to positively cure the dog with an allergy to food as outlined above the problematic constituents just have to be avoided.

Is it likely that my dog could develop other food allergies?

It is not uncommon for dogs that have developed an allergy to one particular food to subsequently develop other food related allergies. If signs re-appear do not immediately jump to the conclusion that your dog has eaten some of the forbidden food. It may be that unfortunately other food related allergies are appearing. Please contact us if you have any concerns.