Adverse reactions to food, whether seen as a food intolerance or a food allergy, is one of the commonest cause of ill health in pets.
Food allergies and food intolerances are not the same. Food allergies work through the immune system and show the characteristic symptoms of itching and skin problems associated with pet allergies. Food intolerances do not work through the immune system and usually result in stomach upsets.
Both can be caused by food types such as proteins or carbohydrates but also by added ingredients such as food colourings and preservatives. This can cause problems for owners when choosing food for their pets as often not all specific ingredients are named on pet food packaging.
Food allergies affect both dogs and cats. There is no strong link between specific breeds and food allergies although it is widely thought that Westies, Cocker Spaniels and Irish Setters are more likely to develop food allergies or intolerances. Food allergies affect both males and females and can show up at any time in a pet’s life. Many animals with food allergies also have other allergies making them difficult to diagnose.
The symptoms of food allergies often mimic those of most allergies seen in dogs and cats. The primary symptom is itchy skin affecting primarily the face, feet, ears, forelegs, armpits and the area around the anus. Symptoms may also include recurrent ear infections, hair loss, excessive scratching, hot spots, and skin infections that respond to antibiotics but reoccur after antibiotics are discontinued. There is evidence that dogs with food allergies may sometimes have an increased incidence of bowel movements.
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 Only once all other causes have been ruled out or treated, is it time to perform a food trial to identify the food the pet is allergic to. This is the only way to accurately diagnose which ingredient is causing the reaction and the process must be strictly adhered to.
A food trial consists of feeding an animal a unique food source of protein and carbohydrate for a minimum of 12 weeks. An example would be a protein and carbohydrate that the animal had never eaten before. Commercial diets are available on the market or the owner can use homemade diets. The pet must only be fed these diets and water during the trial and have no access to treats, human food or food put out for other pets.
If the animal’s symptoms clear up or reduce in severity, then the animal is placed back on the original food to confirm the diagnosis. 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 food source could be tried.
The treatment for food allergies is avoidance and management. Once the offending ingredients have been identified through a food trial, then they are eliminated from the diet. Many cases of food intolerance are dose sensitive – so animals may be able to eat a small quantity of the offending ingredient without any adverse signs. Short-term relief may be gained with fatty acids, antihistamines, and steroids, but elimination of the products from the diet is the only long-term solution. The owner can choose to feed the animal a special commercially prepared diet or a homemade diet. Homemade diets should always be developed with a veterinary nutritionalist to ensure that the pet receives the correct balance of nutrients and vitamins.
There are specialised diets that have the proteins and carbohydrates broken down into such small molecular sizes that they no longer would cause an allergic response.
Owners should be aware that some pets with food allergies may develop allergies to new foods if they are fed those foods long enough
