Dog allergy testing

Could my dog’s diet be making him itch? Cutaneous Adverse Food Reactions (CAFR)

Cutaneous Adverse Food Reactions (CAFR), also known as food allergies, food intolerances, dietary sensitivity or hypersensitivity, can develop at any age. They are seen as skin changes, due to an inappropriate response to one or more ingredients. This could be within the main diet, treats, flavoured medications or scavenged food items on walks. Our vet explains what you might see if your dog reacts to food, and what to do if you think your dog has a skin condition.

This article was written by a FirstVet vet


Did you know that FirstVet offers video calls with experienced, UK registered vets? You can get a consultation within 30 minutes by downloading the FirstVet app for free from the Apple App Store or Google Play.


✓ Included free as part of many pet insurance policies
✓ Help, treatment and if you need it, a referral to your local vet
✓ Open 24 hours a day, 365 days a year

In this article we will discuss:

  • Can food make my dog itch?

  • What are the most common foods that can cause skin problems in dogs?

  • How do I tell if my dog has an allergy to food?

  • What should I do if I think my dog has a food intolerance?

Food reactions can cause a wide variety of changes to the skin. With CAFR, dermatitis is typically seen as inflammation and itching of one of both ears. Dogs may have dermatitis with or without other affected locations on the body. There is no seasonal pattern and no particular breed association. However, the breeds that are prone to allergic skin disease are generally more likely to be affected. Breeds most often affected are German Shepherd Dogs, West Highland white terriers, Labradors and golden retrievers.

A thorough history, appropriate further testing (if indicated) and an elimination diet trial can all help to identify the underlying cause. Food allergy blood tests tend not to be useful for diagnosis. Dietary intolerances are different to the potentially toxic foods dogs can’t eat (such as onions and chocolate). With dietary intolerance not all dogs are affected.

Can food make my dog itch?

Dogs with reactions to food usually have non-seasonal itching (pruritus). This can be difficult to distinguish from atopic skin disease (eczema). One or multiple locations can be affected including, the ears, mouth, lips, paws, groin, armpits, forelimbs, and around the eyes or bottom.

The most common symptoms of CAFR in dogs are:

  • Redness and irritation

  • Weeping, sore eyes

  • Rashes, spots

  • Itching, scratching, licking

  • Crusting, oozing, discharge,

  • Dry, flaky coat

  • Saliva staining (orange discolouration of licked fur)

  • Infections with yeasts or bacteria, that may smell

Dogs can also show signs of allergy (urticaria – hives, facial swelling, or in the worst case, anaphylaxis) or gastrointestinal changes (vomiting, diarrhoea, flatulence, more regular faeces, passing mucus or blood).

What are the most common foods that can cause skin problems in dogs?

It is more common for dogs to react to proteins than carbohydrates. Some can react to multiple foods, which can make diagnosis more challenging. The most commonly seen food allergies in dogs caused by:

  • Beef

  • Dairy products

  • Chicken

  • Wheat

  • Lamb

How do I tell if my dog has an allergy to food?

After ruling out other causes (such as parasites and contact with irritants) an elimination diet trial is recommended. An elimination diet trial normally takes 8 weeks or more. IMPORTANT: No other foods can be offered until the trial is complete. Treats and scavenged food items will affect the results. Diet trial options are:

  1. Home cooking – one new (‘novel’) protein that your dog has not previously encountered, with a carbohydrate. This can be time consuming and nutritionally unbalanced but you can be certain of the ingredients

  2. Commercial limited ingredient diet – a few options may need to be trialled in case one or more contains a trigger ingredient. A vegan or vegetarian brand is an option (see further reading, below). Examples: Hills d/d, James Wellbeloved, Butternut Box

  3. Commercial hydrolysed protein diet – the proteins are broken down into sizes the body cannot detect. Examples: Royal Canin Anallergenic, Hills z/d, Purina HA - potentially eliminating the problems of options 1 and 2

Care must be taken that any chosen diet is age appropriate. The diet can also be fed as a treat during the trial. If the signs resolve, ingredients are reintroduced one at a time as a ‘challenge’ to check for a relapse.

What should I do if I think my dog has a food intolerance?

Skin problems in dogs can be a source of discomfort and distract them from enjoying their daily life. Fortunately, many conditions can be resolved or managed once a thorough work-up and diagnosis has been achieved. Further testing, such as skin scrapes and hair plucks, may be advised. Parasite prevention will be updated if necessary.

If you suspect your dog may have a cutaneous adverse food reaction, a consultation with your vet is recommended to discuss possible causes, and if an elimination diet is appropriate.

Further reading

Still worried?

Book a video appointment to have a chat with one of our vets.

More articles about Dog