Your dog is itchy. Your veterinarian recommends a diet that is considered hypoallergenic. After six weeks your dog is as itchy as ever. Why isn’t the food working? The main reason is that most dogs are allergic to things other than foods. Flower, grass, and tree pollens are the biggest culprits. Fungal spores and insect (fleas, house dust mites) are other common allergens. The second reason the food may not work is because it is not truly hypoallergenic. A recent study of these diets revealed that the majority contained meats not disclosed on the label.
What causes an allergic reaction?
An allergic reaction is an exaggerated response of the immune cells to certain proteins. Certain cells of the immune system attack these foreign proteins. In doing so, the immune cells release large amount of histamines. It is the histamine in the blood stream that causes the symptoms in allergic reactions. The symptoms in humans are primarily sneezing, coughing, runny nose and eyes. In dogs allergic reactions generally results in itching. The itching causes licking and biting that leads to secondary skin infections. Most dogs are allergic to environmental proteins in pollens, plant and fungal spores, dust and insect saliva. But some dogs are in fact allergic to certain meat proteins. Hypoallergenic diets can help these dogs.
What are Hypoallergenic Diets?
Diets are considered hypoallergenic if they contain “novel” proteins. Novel proteins are generally meats that are not common in most dog foods, so dogs have not likely been exposed to them. Lamb, game meats (bison, venison and duck) and fish have all been used for hypoallergenic diets. There are special, limited protein veterinary diets that use these novel meats as a single source of protein. A recent study revealed that these diets may not be single source, limited protein diets after all.
The Study’s Findings
Researchers in Italy tested 11 diets with novel proteins and 1 diet with hydrolyzed proteins. Hydrolyzed proteins are small amino acid chains that don’t cause an allergic response.
The researchers examined the food microscopically to identify bone fragments and classified them as mammal, bird or fish. They also ran DNA test on the diets to determine the same animal classifications. The researchers found that only 2 of the diets actually contained the species specified on the label. The other 10 had bones or DNA of an animal classification that was not listed as an ingredient on the label.
Six of the diets were contaminated with bird protein, five were contaminated by fish protein, and four were contaminated by mammal protein. These 10 diets weren’t single source protein foods. Dogs that are allergic to the contaminated protein would fail to respond to the diet. They would still itch and scratch.
The researchers pointed out that using these foods as a trial for diagnosing food allergy could be misleading due to the contamination. Their recommendation was to use homemade diets to test for food allergies because the limited ingredients can be more carefully controlled.
And if a diagnosis of food allergy is established homemade dog food is the easiest and best way to ensure that an allergic dog is getting a truly hypoallergenic diet.
Dr. Ken Tudor,
THE DOG DIETITIAN