5. Food Allergy

How would you describe an adverse food reaction when there is an immunological reaction?

Food hypersensitivity or food allergy

What is it called when there is an non immunological reaction?

Food intolerance

What type of hypersensitivity is food allergy?

Types I, III, & IV

( I: IgE- allergic anaphylaxis and atopy

III: Immune complex

IV: Delayed)

How would you describe the pathogenesis of food allergy?

Lack of immunologic tolerance orally or in the gut

What are some things that can cause a lack of immunologic tolerance orally or in the gut?

Abnormal GI transit time

Abnormal GI barrier function

Open GI system young animals

Abnormal GI immune system

Endoparasitism skew towards IgE

T/F Most food allergy patient present later in the life

False, earlier in life

What is the most common trigger of food allergy in patient due to be them being antigentic and being able to cross react to other?

proteins

What size do the protein allergens have to be to elicit a food allergy response?

10-70 kD

What are some examples of protein allergens?

Beef, soy, chicken, fish, dairy, egg,pork

What are some examples of carbohydrate allergens?

Corn, wheat, rice (this is why the wanna do the grain free diet)

What is the age of onset for food allergy?

Young & old (>7 yrs)

How would you know if an older patient has developed a food allergy?

it is nonseasonal and causes extreme itchiness

What is the MAIN dermatological sign of food allergy?

Severe pruritus (97%) that is nonseasonal clinical signs

What are some other dermatologic signs that are associated with food allergy?

- Erythema

-papules

- Urticaria-angioedema

- Seborrhea

- Alopecia & lichenification

- Ceruminous otitis externa

- Recurrent pyoderma & pododermatitis

- Lupoid onychodystrophy

- Perianal fistula - rarely

What is the autoimmune disease where there is extreme pain and itchiness at the junction of the claw of P3?

Lupoid onychodystrophy

T/F Food allergy and atopic dermatitis present basically the same but with food allergy the drugs do not work very well

True

What dog is predisposed to Lupoid onychodystrophy and Perianal fistula?

GSD

What are the GI signs of a food allergy patient? (6)

- Vomiting

- Diarrhea

- Loose stools

- Flatulence, belching, borborygmus

- Increased frequency of defecation

- Picky eater

What are the dermatological signs of food allergy in the cat? (4)

• Miliary dermatitis

• Eosinophilic granuloma complex (Indolent ulcer, linear granuloma, eosinophilic plaque)

• Ulcerative dermatitis (head, neck, axilla)

• Self-induced alopecia/hypotrichosis

Where does the lesions for food allergy localize in the dog?

Face, ears, rears, feet, ventrum

Where does the lesions for food allergy localize in the cats?

Same distribution as dogs

• Facial only ->think FOOD!!

You have a cat that comes in due to vomiting and diarrhea. Upon presentation, the cat is super itchy on the face ONLY and has facial eosinophilic lesion. What is one of you top differentials?

food allergy

If there is a lesion in the mouth that may potentially neoplasia or eosinophilic granuloma, what do you need to do to for a definative diagnosis?

FNA

T/F Serology & intradermal testing is reliable for food allergy

False, not reliable (they are not reliable)

Why is serology and intradermal testing not reliable?

- Changes in proteins during digestion

- Differences in Ags tested & those causing disease

- Not IgE-mediated for many cases

What is the ONLY reliable method to use to get a definitive diagnosis when looking at a food allergy patient?

Elimination diet trial & rechallenge

Describe the process of going through a Elimination diet trial & rechallenge

Duration:

- Until clinical signs resolve

- 8-12 weeks total

Confirmation: Symptoms recur with provocation

What are some examples of elimination diets? (2)

1. novel protein diet

2. hydrolyzed protein diet

What is the IDEAL elimination diet?

1 CHO and 1 protein source only

T/F You cannot used any flavored medication, treat, people food, when doing an elimination diet trial

True

What are some examples of protein sources that are seen in the diet trial?

- Lamb

- Fish

- Venison

- Duck

- Rabbit

- Tofu

- Pinto beans

- Goat

- Kangaroo

- Ostrich

- Alligator

What happens when a dog's immune system mistakes a new or untasted protein for an allergen it already reacts to, because the proteins share a similar structure?

cross reactivity

What are some examples of foods that are seen in elimination diets that could have cross reactivity?

- beef and dairy

- beef and venison

- beef and lamb

- ragweed and bananas ( and other fruits)

- Birch trees and apples

- grass pollen and several fruits

- mugwort pollen and several fruits and veggies (not WTH)

What is the GOLD standard for elimination diet?

Home-cooked diets

What type of diets should you ALWAYS reccommend? (think public health)

cooked diets

T/F There are NO benefits shown with raw for food allergies

True

What are TWO reasons why you should cook diets rather than have raw diets?

- Opportunistic infections from diets (e.g.,

Salmonella, E. coli)

- Public health risk with raw diets

What elimination diet has a veterinary formulated commercial diets?

Novel protein

Just read this

okay girl

How can High in omega-3 FAs lead to a false positive in the diet trial?

High in omega-3 FAs -> reduce inflammation -> false positive

response to diet trial (this is because it helps to build the skin barrier back)

How does a hydrolized protein diet work?

Reduction of molecular size to avoid binding to IgE

What size are the majority of the hydrolized protein diets?

< 3 kDa (some

When will a hydrolized protein diet not be effective?

not all cases are IgE- mediated

How long does an elimination diet trail last?

8-12 weeks (2 diet trials before ruling out)

T/F You need to feed the original diet for 2 weeks at the end of the trial to confirm that they are actually itchy

True

What response are you looking for when finishing the elimination diet trial?

Remission of clinical signs

What anti-pruritic medications should be given during trial period?

Steroid, JAKi

What is REQUIRED for a definitive diagnosis of the food allergy?

Elimination Diet Trial Challenge

You are doing a elimination trial and at the end of the trial you feed 50:50 old diet for 2 weeks. When you feed the mix of the diet, there is no clinical signs that return. What can you conclude from this?

not a food allergy ( clinical signs have to return to diagnose this)

What are TWO options for post diagnosis of food allergy?

1. Veterinary formulated commercial diet for life

2. Single ingredient challenge

What is the management and prognosis for food allergy patients?

- Management = avoidance

- Prognosis = excellent

T/F You can do a single ingredient challenge to figure out exactly what is causing the issue

True