Adverse Food Reactions

Question 1

What is the pathogenesis of food allergies? What are some likely causes?

Answer 1

absorbed food proteins of 10000-60000 daltons cause a Type I or IV reaction –> looks like atopic dermatitis!

• genetics
• alternation in gut permeability
• dysbiosis

Question 2

What are 4 non-immunologic reactions associated with adverse reactions to food?

Answer 2

1. food intolerance
2. idiosyncratic adverse reactions (additives)
3. pharmacologic - vasoactive amines (histamine)
4. food poisoning

Question 3

What are the most common offending substrates that cause ARFs in dogs?

Answer 3

• beef
• diary - skim milk, whey
• wheat
• poultry - chicken, meal, eggs
• lamb
• soy
• corn (starch)
• pork
• rice
• fish

Question 4

What are the most common offending substances that cause ARFs in cats?

Answer 4

• beef
• dairy
• fish
• poultry
• corn
• lamb
• pork

Question 5

Cross-reactivity:

Answer 5

Question 6

What age is associated with AFRs?

Answer 6

<1-3 y/o, but seen at any age

Question 7

What are 3 historical features associated with AFRs?

Answer 7

1. non-seasonal
2. same diet for an extended time (not associated with dietary changes)
3. poorly responsive to glucocorticoid therapy

Question 8

What are 5 PE findings in ARFs in dogs?

Answer 8

1. non-seasonal pruritus - face rubbing, foot licking, generalized
2. otitis externa
3. recurrent superficial pyoderma or folliculitis
4. interdigital pyoderma
5. GI signs - increased frequency of defecation, borborygmus, vomiting, IBD-like signs, seborrhea, urticaria, excessive gas, soft stools

Question 9

AFR, dog:

Answer 9

signs typically return after glucocorticoid or antibiotic treatment

Question 10

AFR:

Answer 10

superficial pyoderma - r/o atopy vs food

Question 11

What are 5 PE findings in cats with AFRs?

Answer 11

1. pruritis - commonly on head, neck, ventral abdomen, pinnae
2. facial dermatitis
3. otitis external
4. reaction patterns - eosinophilic dermatitis, indolent ulcers, miliary dermatitis, self-induced (symmetrical ventral) alopecia
5. extracutaneous - GI, conjunctivitis

Question 12

AFR, cat:

Answer 12

pinna and head commonly affected

Question 13

AFR, cat:

Answer 13

reaction pattern - miliary dermatitis

• flea bite hypersensitivity vs. atopy vs food

Question 14

AFR, cat:

Answer 14

symmetrical licking down neck

Question 15

Food vs environmental allergies:

Answer 15

Question 16

When should allergy testing or food trials be recommended for an itchy patient?

Answer 16

ALLERGY TESTING - fulfills criteria, breed, classical signs, seasonal, response to treatment

FOOD TRIAL - signalment, non-seasonal, poor response to treatments, cat

Question 17

How does cause of pruritis compare in dogs and cats?

Answer 17

DOGS - AFR = 10-30%

CATS - AFR = 50-90%

Question 18

What are clinical features used to diagnose AFRs? What specific diagnostic is recommended? Avoided?

Answer 18

poor response to glucocorticoid therapy

hypoallergenic (elimination) diet trial - 8-12 weeks, look for >50% improvement

allergy testing

Question 19

What does diagnosis of AFR require?

Answer 19

control secondary infections/issues –> dietary trial for 8-12 weeks –> challenge with original diet –> provocative exposure to identify offending allergens

Question 20

What home-cooked diets can work as novel protein diets for trials in dogs and cats?

Answer 20

DOGS - emu and rutabaga, pinto beans and rice, pork and rice, green beans and applesauce, tofu and rice, pumpkin and pinto beans

CATS - require little to no carbohydrates

• NOT balanced diets, only recommended for limited time
• can be formulated to be balanced using veterinary resources

Question 21

What are 4 options for commercial novel protein diets for trials?

Answer 21

1. Hill’s d/d - potato and salmon, egg and rice, potato and duck, potato and venison
2. Royal Canin Select protein - kangaroo and oats, potato and venison, potato and fish
3. Royal Canine vegetarian formula
4. Blue Buffalo Novel Portein - alligator

Question 22

What are hydrolysate diets?

Answer 22

proteins broken down in size (<1500 daltons) to reduce allergenicity –> commonly combined with novel protein diets

• feather protein
• chicken liver
• salmon soy

Question 23

What are some options for feline hydrolyzed protein diets?

Answer 23

• Royal Canine Hypoallergenic - Brewer’s rice and hydrolyzed soy
• Hills z/d - Brewer’s rice and chicken liver
• Royal Canin Ultamino - corn starch and poultry aggregate
• Hills d/d

Question 24

What kind of diet is Purina Pro Plan EL?

Answer 24

proteins are broken down to an amino acid (oligopeptide) level

Question 25

Are skin support diets acceptable for dietary trials?

Answer 25

NO - neither novel proteins nor hydrolized proteins - do contain fatty acids for barrier function - OTC diets NOT reliable, often contaminated

Question 26

When may grain free diets show improvment in animals with AFRs?

Answer 26

if they are allergic to wheat - clear association with DCM in dogs

Question 27

Dog hypoallergenic diets:

Answer 27

Question 28

Cat hypoallergenic diets:

Answer 28

Question 29

How long should a hypoallergenic trial extend in dogs and cats?

Answer 29

DOGS - minimum 5 weeks --> 8-12 raises sensitivity CATS - minimum 6 weeks --> 8 weeks raises sensitivity

Question 30

AFR:

Answer 30

utricaria

Question 31

What are keys to a successful dietary trial?

Answer 31

- know who is feeding the pet - eliminate all snacks and treats, including rawhides - NO flavored medication (heartworm) - administer medication with marshmallows, fruit roll-ups, or cubes of potato/rice - have owner keep a log or diary - regular phone check-ups

Question 32

What treats can be given to animals on a food trial?

Answer 32

- hypoallergenic treats - check ingredient list! - ice chips - food part of the trial

Question 33

When is a positive response to a dietary trial expected?

Answer 33

within weeks - ranges from 2-12 weeks on the diet - owners may not notice a change until the pet is put back on the original diet - 100% improvement is only possible if a food allergy is the only problem --> concurrent atopy, perpetuating infections

Question 34

Does a positive dietary response confirm an adverse food reaction?

Answer 34

NO - other disease conditions (atopy) may respond to hypoallergenic diets rich in fatty acids

Question 35

How are AFRs confirmed? Specific causes?

Answer 35

dietary challenge - induce a relapse of clinical signs by restarting old diet and treats --> expect signs to occur within minutes to 14 days provocative exposure - add new ingredient every 7-10 days, if no reaction, continue with hypoallergenic diet for 7 days and add a new ingredient --> goal is to find a commercial diet that is acceptable

Question 36

What long-term therapy is recommended for AFRs?

Answer 36

- avoid allergens - control secondary infections - crucial if these are key manifestations, treat while starting dietary trial

Question 37

What tends to happen in dogs with environmental and food allergies? How are these dogs identified?

Answer 37

perceived failure to diet trials AND atopy therapies - control all secondary issues - allergy test to confirm atopic dermatitis - treat atopic disease to get a 50% reduction in itch - start a food trial

Question 38

What solid data is there of raw meat diets?

Answer 38

significant public health risk --> clear increase in fecal E. coli, Listeria, and Salmonella counts