Dog Food Allergies and Skin Problems
Food allergy or intolerance?
There is a distinction that needs to be made between food allergies and food intolerances. Food allergies are true allergies and show the characteristic symptoms of itching and skin problems associated with canine allergies. Food intolerances can result in diarrhea or vomiting and do not create a typical allergic response. Food intolerances in pets would be similar to people that get diarrhea or an upset stomach from eating spicy or fried foods. Fortunately, both food intolerances and allergies can be eliminated with a diet free from offending agents.
Common food culprits
Several studies have shown that some ingredients are more likely to cause food allergies than others. In order of the most common offenders in dogs are beef, dairy products, chicken, wheat, chicken eggs, corn, and soy. Pet foods have historically been made up of beef, chicken, corn, and wheat. In an effort to combat food allergies, several companies produced a diet made of lamb and rice. There was nothing special about lamb and rice diets except those two ingredients were normally not present in pet foods. Animals had not eaten lamb or rice before, and therefore, had not developed an allergy to it yet. The determinant of whether a food is likely to cause a food allergy or not is based on the structure and size of the glycoprotein in the food. In addition, many lamb and rice-based foods contain many other ingredients, and if the animal has a food allergy to any of them, this lamb and rice food will do nothing to treat the food allergy.
Symptoms of Food Allergies
The symptoms of food allergies are similar to those of most allergies seen in dogs. The primary symptom is itchy skin. Symptoms may also include chronic or recurrent ear infections, hair loss, excessive scratching, hot spots, and skin infections that respond to antibiotics but reoccur after antibiotics are discontinued.
It is difficult to distinguish an animal suffering from food allergies from an animal suffering from atopy or other allergies based on physical signs. However, there are a few signs when you can suspect food allergies. One of these, is a dog with recurrent ear problems, particularly yeast infections. Another, is a very young dog with moderate or severe skin problems. A third tip off, is if a dog suffers from allergies year-round or if the symptoms begin in the winter. And the final clue, is a dog that has very itchy skin but does not respond to treatment.
The diagnosis for food allergies is very straightforward. But due to the fact that many other problems can cause similar symptoms and that many times animals are suffering from more problems than just food allergies, it is very important that all other problems are properly identified and treated prior to undergoing diagnosis for food allergies. Atopy, flea bite allergies, intestinal parasite hypersensitivities, sarcoptic mange, and yeast or bacterial infections can all cause similar symptoms as food allergies.
Once all other causes have been ruled out or treated, then it is time to perform a 12 week food trial diet. A food trial consists of feeding an animal a novel food source of protein and carbohydrate for 12 weeks. A novel food source would be a protein and carbohydrate that the animal had never eaten before (example rabbit and rice). If the dog shows a marked reduction or elimination of the symptoms, then the animal is placed back on the original food.
If the symptoms return after going back on the original diet, the diagnosis of a food allergy is confirmed. If there has been no change in symptoms but a food allergy is still strongly suspected, then another food trial using a different novel food source could be tried. Placing a dog on a commercial lamb and rice formula dog food is not an acceptable way to diagnose or treat food allergies. Lamb and rice are no longer considered novel food sources and most commercial lamb and rice diets also contain wheat, egg, corn, or other ingredients that can be the cause of the food allergy.
Once a food allergy is positively identified, then the treatment is very straightforward. The owner of the animal has two choices. You can choose to feed the animal a special commercially prepared diet or a homemade diet.
If you choose to feed the homemade diet, then you can periodically challenge the pet with new ingredients and determine which ingredients are causing the food allergy. For example, if the animal's symptoms subsided on a diet of rabbit and potatoes, then you could add beef to the diet for two weeks. If the animal showed no symptoms, then you could then add chicken for two weeks. If the animal began to show symptoms, then it could be assumed that chicken was one of the things the pet was allergic to. The chicken could be withdrawn and after the symptoms cleared up, a different ingredient could be added and so on until all of the offending ingredients were identified. A diet could then be formulated that was free of the offending food sources.
If your pet is still suffering from skin problems despite changing the diet and eliminating corn, wheat and other grains; then he may possibility be having an allergic reaction to new carpet fumes and chemicals, or have an itchy skin infection with hair loss due to bacteria, virus, or fungi. Your veterinarian will be able to perform a skin test to find the possible cause of the skin irritation and recommend treatment.