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05th May 2017

Food Allergy or Food Intolerance?

by Laura Crotch-Harvey MSc BSc (Hons)

Have you noticed your precious pooch itching more recently? Does your friendly feline or prized pooch appear to be suffering from allergies? Confused by the difference? Our expert nutritionists have outlined the differences between a pet food allergy and a pet food intolerance to help you understand their needs a little more.

Is a food allergy and intolerance the same? The simple answer is no. A pet food allergy involves the immune system and is usually triggered by a response to a protein.

pet food intolerance is an abnormal response to an ingredient but it does not involve the immune system.

The symptoms of both can be very similar. Allergy tests can only detect food reactions which involve the immune system so the only true way to determine an adverse food reaction is by feeding an elimination diet.

Symptoms of adverse food reactions in pets affecting the digestive system:

  • vomiting and/or diarrhoea
  • abdominal pain and/or bloating
  • occasional diarrhoea
  • flatulence
  • soft/loose stools

Affecting the skin…

  • itchy skin
  • inflamed skin
  • scaly, crusty patches of skin

If your pet is itching, this may be caused by:

  • flea allergy dermatitis (FAD), very common in dogs and cats and caused by a sensitivity to flea saliva – this can be caused by just one or two flea bites. Owners may not even see fleas on their pet; excessive grooming by hypersensitive pets often removes any evidence
  • environmental allergens (e.g. pollen) – this type of allergy is known to be inherited. Dogs and cats suffering from an allergy should not be bred from

If your pet has problems with digestive upset, this may be caused by:

  • scavenging
  • eating too much or fatty food
  • parasites
  • infection

How can you help your pets to avoid an adverse food reaction?

In most cases adverse food reactions develop over time, therefore if you have a healthy dog or cat you should consider rotating between food varieties to avoid your pet being exposed to the same ingredients over and over. This should also help to identify whether or not there is an adverse food reaction (you may see your pet improve or worsen on one particular variety). However, if your pet has already had problems and is doing well on one particular variety of food it may be best to continue with this diet. Please speak to one of our nutritionists before changing diets.

Most common food allergies

Beef Dairy Fish Wheat
Dogs Dogs Dogs
Cats Cats Cats

Dog breeds most commonly affected by food sensitivity

Westies Cocker Spaniels Irish Setters Shar Pei German Shepherds

The breeds listed above are just a small number of the dogs who are more commonly affected by food sensitivity.

The areas most affected are the face, paws, lower legs, groin, and, less often, the ears and eyes. In addition to scratching themselves with their hind feet, dogs often lick or chew the affected areas, or rub along the carpet to scratch their face or ears. Initially, there are no apparent skin abnormalities, except possibly slight reddening, even though the dog is clearly itchy. (This is important because in other conditions there is often a rash or some visible lesion).

Over time lesions develop as a result of the scratching and self-trauma, bacterial or yeast infections, and seborrhea, all of which can contribute to the ‘smelly dog’ odour. The skin becomes reddened and eventually darkened (hyperpigmentation), abraded, thickened, and wrinkled, with loss of hair and bronze staining from saliva.

Gastro-intestinal symptoms may include diarrhoea, increased frequency of passing motions, increased stool volume, highly unpleasant smelling stools, vomiting, bad breath, flatulence and inappetence.


Some studies have shown Siamese cats and Siamese crosses are more likely to have skin issues.

Similar to dogs, cats will develop itchy skin when an allergy is present. Cats will rarely lick and scratch in front of owners so looking out for other signs is vital. Furballs or hairs around the tounge, teeth or house will be a good indicator that your cat is over-grooming and licking excessively. Some cats will appear to go bald from over-grooming. Cats can also develop ulcers and moist weeping sores around the head and neck region when a food allergy is present.

Don’t forget!

Treats, supplements, dental chews, rawhide and even some medications all have ingredients that your pet could react to. When trying to avoid certain ingredients in the main diet you will need to look at the composition of these items too.

How common are adverse food reactions in pets?

Only 1-6% of skin problems in dogs and cats are thought to be caused by food according to veterinary dermatologists. Flea sensitivity & environmental allergies are much more common.

Between 10-49% of all allergic reactions (skin, digestive, respiratory etc) are thought to be caused by a reaction to food, however several studies have shown that cats are more commonly affected than dogs.

If you suspect that your pet has a food allergy/intolerance…

  • look for a hypoallergenic food as this avoids common allergens like beef or wheat
  • choose a diet with a single protein (meat/fish/egg) source
  • choose a diet with novel ingredients (ones your dog or cat has not eaten before or very often)
  • follow our elimination diet guide

And lastly, contact a friendly Burns nutritionist for advice. Our nutritionists are on-hand every Monday to Friday 9am to 5pm to answer all your pet nutrition enquiries. Reach them on freephone number 0800 083 66 96 or email to communicate digitally.

by Laura Crotch-Harvey MSc BSc (Hons)

I've worked at Burns for over four years and head up a busy, dedicated team of pet nutritionists at our Kidwelly head office. No two days are ever the same. We are often busy going the extra mile for our customers and offer free advice via LiveChat, telephone and email.

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