Potato Allergies in Dogs

When the immune system responds forcefully to a perceived threat, in this case, potatoes, an allergic reaction occurs. Potatoes are a common canine allergen due to the preponderance of allergen types that are contained within the potato, and they are frequently used as a carbohydrate source in foods and treats. Canines who develop food allergies, like allergies to potatoes, will experience inflamed and itchy skin and are prone to developing chronic conditions such as indigestion, ear infections, and wheezing. Although rare with canines, anaphylactic shock may also occur with food allergies. Dogs who have been diagnosed with allergies to other types of foods are more likely to develop allergies to new food sources.

An allergy to potatoes is an over-reaction of your dog's immune system to an unwelcome protein that is present in the tubers themselves.

Food allergies are more common in adult dogs, but can happen at any age. Signs that your dog is allergic potatoes might include: 

• Bald patches
• Biting of paws
• Chronic ear infections
• Chronic gas
• Coughing 
• Difficulty walking
• Face rubbing
• Hives
• Inflamed feet
• Obsessive licking
• Poor growth 
• Skin infections
• Skin rashes
• Vomiting
• Wheezing

Dogs do not often develop anaphylactic shock due to food allergy, but it does happen. The anaphylactic shock should be treated as an emergency, and your pet should be rushed for treatment to the nearest veterinary hospital if the following signs develop. These symptoms could include:

• Cold limbs
• Coma
• Difficulty breathing
• Elevated heart rate
• Excessive drooling
• Low blood pressure
• Pale gums
• Seizures
• Sudden diarrhea
• Sudden vomiting

Types

Potato plants, like many other plants in the Solanaceae family, produce a type of neurotoxin known as glycoalkaloids. These toxins are generally restricted to the green portions of the plant, particularly the stems and shoots, but can also be found in potatoes that have turned green, usually due to sun damage during their growth. Any green portions of potatoes should be removed before cooking.

Allergies to potatoes are due to an unwarranted defensive response to a protein in the potato that your dog’s immune cells view as an intruder. 60-70% of the immune system cells are estimated to reside within the digestive system of mammals, mostly as white blood cells called enterocytes. The digestive system breaks down the food we eat into their smallest parts, called amino acids, which are then absorbed by the enterocytes. When the proteins from the potato are not entirely broken down during the digestive process, the enterocytes then view these particles as intruders instead of as nutrients and attack them. The response of the white blood cells to the proteins in the potato will, over time, become more aggressive which causes the symptoms to become more intense. 

An allergy to one or more of the amino acids found in potatoes can also cause localized itchy rashes when the juice from the potato contacts the skin.

Due to the skin related symptoms of an allergic reaction, your veterinarian will collect skin sample by scraping the cells off the surface of the affected skin. A microscopic evaluation of the collected skin cells, called cutaneous cytology, will be done to search for signs of mites, yeast infections, or other diseases. If no other underlying causes are brought to light, a food allergy may be suspected. An elimination diet is usually utilized to confirm the diagnosis of a food based allergy. An elimination diet is done by replacing the food your dog is currently eating with either a new diet of limited-ingredient or hypoallergenic commercial dog food or a diet of bland human food. This process usually takes several weeks, and it is essential that your dog does not ingest anything other than the food that has been chosen as the replacement food during the elimination trial. A single treat that includes the allergen can cause the allergy to resurface and derail the entire process. 

All of the ingredients that constitute the dog’s current diet should be avoided when choosing the replacement food source as the symptoms may be triggered by multiple allergens. It is also possible that your pet is allergic to the entire food family, so avoiding food that is similar to past foods may prove to be more efficient. Other foods in the plant family that potatoes belong to, Solanaceae, also includes plants like tomatoes, eggplant, peppers, and tobacco. If your pet has a predisposition for food allergies multiple allergens may be involved. A properly executed elimination trial will cause the signs of allergy to cease until the allergen is reintroduced.

Elimination diets take several weeks to confirm that an allergy exists, and may take even longer to expose that the allergy is to potatoes or in the Solanaceae family. Your dog may continue to experience symptoms until the food antigens that are causing the reaction have been expelled from his system. Veterinarians will often choose to complete the diagnosis through the elimination diet before applying symptomatic medications such as antihistamines or corticosteroids to relieve itching and swelling. Although these preparations can be highly efficient at easing dermal symptoms, they are also capable of obscuring the ultimate source of the allergic reaction by masking the allergic reactions. 

Secondary skin infections are common due to the damage to the epidermis and antibiotics are often prescribed to eliminate these conditions. Once the source of the allergy has been identified as potato, you will need to avoid feeding that ingredient to your dog in the future. Potatoes belong to the same family of plants as eggplant, tomatoes, and peppers, so a dog that is allergic to potatoes may be prone to developing these allergies as well.

Potatoes are a good source of vitamins and minerals for the average dog, however for canines who are allergic to potatoes they can cause a great deal of discomfort. Food allergies are not a curable disorder, but the allergy related symptoms are easily dispersed by cutting the allergens from your dog’s diet. If your dog has exhibited an allergic response to one kind of food, they are more likely to acquire new food-related allergies, particularly foods similar to the one they are allergic to. 

The approach to preventing new allergies due to this tendency varies within the veterinary profession, with some veterinary professionals maintaining that a steady rotation of three of four novel protein foods is optimal and other advocating that your pet remains on a single source of food as long as new allergies do not develop.