Problems with food are actually quite common in animals. Many times these problems are undiagnosed. Subtle indicators that may indicate food issues include indigestion, lip smacking, eating grass, flatulence, and finickiness. More serious symptoms include vomiting, diarrhea, itching, chewing, face rubbing, skin infections, and ear infections. Inflammatory bowel disease and irritable bowel disease may also have their origins in food intolerances. Behavior issues, coughing, lethargy, poor appetite, and pica (ingestion of non food items) can also indicate food issues. Sometimes the problem is not the food itself, but colors, dyes, contaminants, or vitamin/mineral mix added to the food. Processing of raw ingredients destined for the food can also introduce reaction-provoking chemicals.
If your animal is showing subtle signs, a good first step is to try a diet free of the common allergens chicken, corn, wheat, and soy. Using a good quality limited ingredient diet for 4-8 weeks can help you to determine if your animal is intolerant of one or more of these allergens. An alternative approach would be to use a dehydrated diet or pre-mix where you add your own protein, making sure in each case to avoid the common allergens. Dehydrated diets are soaked in water before feeding.
Because the more serious symptoms can also be caused by disease, getting your animal a good physical exam and appropriate testing is next. Once you know food is the likely culprit then you have several choices:
The newest approach to determining trigger foods is Nutriscan, a saliva test which identifies intolerances to 24 foods commonly found in commercial pet diets: Beef, Corn, Lamb, Venison (deer), Chicken, Turkey, Pork, Duck, Rabbit, Rice, Soy, Quinoa, Barley, Millet, Oatmeal, Cow's Milk, Potato, Sweet Potato, Salmon, White-Colored Ocean Fish (includes menhaden, pollack, herring, sardines), Lentils, Chicken Eggs, Peanut/Peanut Butter. The Nutriscan kit contains a small cotton rope which can be held in the animal’s mouth to soak it with saliva first thing in the morning before breakfast. The rope is then sealed in the provided vial and sent to the lab for processing. This test can be done at home. Once results are received, a food can be selected which is free of the problem items. The labels of any treats or supplements must also be reviewed to be sure they do not contain any reactive items. This can be challenging if potatoes, sweet potatoes, lentils( this includes peas), salmon, and/or white fish are flagged because these items are widely prevalent in pet foods. You can read more about Nutriscan at www.nutriscan.org/.
Many veterinarians still believe an elimination diet is the only way to diagnose food allergies. A home made diet consisting of a never-before-eaten single protein and single carbohydrate can be prescribed. Frequently these diets are not balanced yet must be fed for at least 4-8 weeks in order to rule out food allergies. If the animal’s symptoms improve, then foods are added back one at a time looking for foods which trigger symptoms. This is a lengthy process and increases the period when the animal is eating an unbalanced diet. More commonly, newer prescription diets may be used. Hydrolyzed diets contain protein broken down into smaller units thought unlikely to cause an allergic response. Low molecular weight diets are similar to hydrolyzed diets in that proteins are broken down into molecules too small to provoke a reaction. Novel protein diets reduce allergic reactions by feeding food the animal has never eaten before. There are several problems with the elimination diet approach. Reactive foods are not identified. Some animals will have a reaction to the diet. Long term use of a prescription diet may be required. Given the wide availability of commercial diets containing novel proteins such as rabbit, goat, and kangaroo it is almost impossible to find an animal protein that has not been previously encountered.
Radioallergosorborent test (RAST)
This test has largely been replaced by the newer ELISA (enzyme-linked immunosorbent assay). Both require a blood sample which is then tested for response to an allergen panel. This test is less frequently used than the first two methods when looking for food allergies.