Just like in humans, your dog's dry, itchy, flaky skin can be a symptom of a food allergy. But also as with humans, it can take some serious searching to find the culprit for Fido's uncomfortable (and unsightly) troubles.
Allergy or Intolerance?
Complicating the question of whether your flaky pup is suffering from a food allergy is general misunderstanding of what defines allergy, as opposed to digestive intolerance.
True allergies are serious business. They usually begin with mild discomfort, including flaky skin, but can lead to anaphylaxis -- contact with the culprit food stops your pup's breathing. Allergies may appear suddenly or grow progressively worse over time. They almost never occur upon first contact.
Digestive intolerance can be an early warning sign of a developing allergy, but is not a true allergic reaction. Food intolerance causes general signs of inflammation, including nausea, vomiting, diarrhea, constipation or blood-tinged stool -- and itchy, flaky skin. Intolerances are usually cumulative -- reaction increases with the amount of culprit food and gets worse over time.
Secondary Skin Infections
Confusing the matter further, your dog's flaky skin might be a symptom on top of a symptom -- a secondary yeast or bacterial infection due to depressed immunity from the original allergy. Sometimes these clear up when the allergen is eliminated, other times they need to be treated with antifungals or antibiotics. A warning sign for an underlying food allergy is when a known fungal or bacterial infection does not clear up with drug treatment alone.
Eliminate the Flakes
Diagnosis of food allergy or intolerance usually involves an elimination diet. These need to be strictly followed, usually for a minimum of 12 weeks, and should be conducted under the guidance of a veterinarian. Your vet may prescribe a specific homemade diet made of limited ingredients (such as lamb and sweet potatoes only), but it is more likely that she will put your pet on a packaged prescription diet made of hydrolyzed ("purified") protein. After a certain amount of time, you will begin adding foods back into the diet one by one to see which ones cause your pup's complaints to resume.
If the elimination or prescription diet is unsuccessful, or if you or your veterinarian feel that time is of the essence, your vet may prescribe a subdermal allergen test.
Deciphering Dog Food
Beware of hidden allergens! Products that contain animal digest, animal fat, dried animal digest, liver, meat and bone meal, meat by-products, meat meal and tallow and powdered cellulose can have ingredients that vary from batch to batch.
Fatty acid supplementation is a common treatment for flaky skin regardless of cause. Many oils are recommended, including olive, coconut, linseed, flaxseed, fish, fish liver, krill, bacon grease and eggs. Opinions are divided on which ones are helpful for dogs, and whether or not dogs can fully metabolize vegetable fats.
Do not rely on your intuition when it comes to diagnosing a food allergy or intolerance. Work with your veterinarian. Many dangerous and contagious conditions, including sarcoptic mange, have flaky, inflamed skin as a symptom.
Angela Libal began writing professionally in 2005. She has published several books, specializing in zoology and animal husbandry. Libal holds a degree in behavioral science: animal science from Moorpark College, a Bachelor of Arts from Sarah Lawrence College and is a graduate student in cryptozoology.