Food allergies are a reaction of the immune system to specific proteins within the diet.
• Food allergies present as persistent itchiness, primarily around the neck and head in cats
• Scratching often leads to skin damage and hair loss, which can lead to secondary bacterial or yeast infections
• Food allergy is diagnosed by elimination of other potential causes of itch through physical examination, assessment for fleas, skin scrapings, and other diagnostic tests.
• Once a food allergy is suspected, an elimination diet or a hydrolyzed protein diet is fed to confirm diagnosis
• Food items are then reintroduced to see if symptoms recur
• Proteins linked with symptom recurrence are identified as dietary allergens
• Once allergens are identified, removal of the allergen stops the symptoms
Food allergies are uncommon in cats, as the majority of allergies in cats are triggered by exposure to flea saliva, or inhaled allergens including mold and pollen. Although food allergies are not an emergency, prompt veterinary care is important to allow treatment of symptoms. Treating food allergies requires extensive testing and trial and error to successfully identify the allergen. Once identified, removing the allergen reduces symptoms significantly.
Cats may also develop skin or ear infections associated with food allergies. Symptoms of these infections include:
• Head shaking • Scratching at the ears • Dark discharge from the ears • Foul odor • Pus oozing from the skin
As with all cases of allergies, the root cause is unknown, but genetic predisposition is suggested. Food allergies are caused by the immune system recognizing a specific allergen in the pet’s diet, and targeting it as if it were a danger to the body. The most common food allergens in cats include:
• Meat proteins such as beef, pork, or chicken • Eggs • Vegetables • Grain products such as wheat, barley, or corn
The main symptoms of food allergies include:
• Skin itching (pruritus) • Reddening, swelling, or crusting of the skin • Bald patches or hair loss
• Damage to the skin such as scrapes or scratches
Approximately 10-15% of cats with a food allergy will also show gastrointestinal symptoms as well (vomiting, diarrhea, etc).
Diagnosing a food allergy begins with a physical examination. Skin scrapings or biopsies may be used to rule out other conditions such as sarcoptic mange or bacterial infections. Once food allergies are suspected, a food elimination trial is conducted to determine the cause of the allergic reaction.
A novel diet plan requires eliminating any protein and carbohydrate sources from the cat’s diet that the cat had previously eaten. Under the guidance of the vet, the protein is replaced with a less common source or a hydrolyzed protein diet.
**It is important to note that a grocery store ‘hypoallergenic food’ is not regulated as stringent as a veterinary prescription diet, so there may be contamination in the food. **In addition, for the diet to be effective, the cat must be monitored in all foods it consumes. This includes table scraps, treats, and anything they may consume while outdoors. To effectively determine the cause, there has to be no other food input to contaminate the reaction.
After a period of 8-10 weeks, if a food allergy is present, the symptoms disappear. Once confirmed, other sources of food are slowly reintroduced one at a time. If the allergy symptoms return, generally within 1-2 weeks after reintroduction, that re-added source is determined to be an allergen. This process can be repeated for all potential allergens. Once the allergens are identified, they are removed from the diet and the symptoms will cease.
Allergies are a lifelong condition. Symptoms continue as long as the allergen is still in the cat’s diet. Once the sources of the allergic reaction are removed, the symptoms should disappear. If the cat still shows consistent itching, it is possible they have atopic dermatitis or FAD in addition to the food allergy. These symptoms need further investigation and treatment.
Allergies are not contagious, nor can they be prevented. Once a food allergy is confirmed through diet elimination, symptoms can be prevented by removing the known allergens from the diet.
Food allergies are uncommon in cats.
• Remove confirmed allergens from diet
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