Adverse Food Reactions Flashcards
What is the pathogenesis of food allergies? What are some likely causes?
absorbed food proteins of 10000-60000 daltons cause a Type I or IV reaction –> looks like atopic dermatitis!
- genetics
- alternation in gut permeability
- dysbiosis
What are 4 non-immunologic reactions associated with adverse reactions to food?
- food intolerance
- idiosyncratic adverse reactions (additives)
- pharmacologic - vasoactive amines (histamine)
- food poisoning
What are the most common offending substrates that cause ARFs in dogs?
- beef
- diary - skim milk, whey
- wheat
- poultry - chicken, meal, eggs
- lamb
- soy
- corn (starch)
- pork
- rice
- fish
What are the most common offending substances that cause ARFs in cats?
- beef
- dairy
- fish
- poultry
- corn
- lamb
- pork
Cross-reactivity:
What age is associated with AFRs?
<1-3 y/o, but seen at any age
What are 3 historical features associated with AFRs?
- non-seasonal
- same diet for an extended time (not associated with dietary changes)
- poorly responsive to glucocorticoid therapy
What are 5 PE findings in ARFs in dogs?
- non-seasonal pruritus - face rubbing, foot licking, generalized
- otitis externa
- recurrent superficial pyoderma or folliculitis
- interdigital pyoderma
- GI signs - increased frequency of defecation, borborygmus, vomiting, IBD-like signs, seborrhea, urticaria, excessive gas, soft stools
AFR, dog:
signs typically return after glucocorticoid or antibiotic treatment
AFR:
superficial pyoderma - r/o atopy vs food
What are 5 PE findings in cats with AFRs?
- pruritis - commonly on head, neck, ventral abdomen, pinnae
- facial dermatitis
- otitis external
- reaction patterns - eosinophilic dermatitis, indolent ulcers, miliary dermatitis, self-induced (symmetrical ventral) alopecia
- extracutaneous - GI, conjunctivitis
AFR, cat:
pinna and head commonly affected
AFR, cat:
reaction pattern - miliary dermatitis
- flea bite hypersensitivity vs. atopy vs food
AFR, cat:
symmetrical licking down neck
Food vs environmental allergies:
When should allergy testing or food trials be recommended for an itchy patient?
ALLERGY TESTING - fulfills criteria, breed, classical signs, seasonal, response to treatment
FOOD TRIAL - signalment, non-seasonal, poor response to treatments, cat
How does cause of pruritis compare in dogs and cats?
DOGS - AFR = 10-30%
CATS - AFR = 50-90%
What are clinical features used to diagnose AFRs? What specific diagnostic is recommended? Avoided?
poor response to glucocorticoid therapy
hypoallergenic (elimination) diet trial - 8-12 weeks, look for >50% improvement
allergy testing
What does diagnosis of AFR require?
control secondary infections/issues –> dietary trial for 8-12 weeks –> challenge with original diet –> provocative exposure to identify offending allergens
What home-cooked diets can work as novel protein diets for trials in dogs and cats?
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
What are 4 options for commercial novel protein diets for trials?
- Hill’s d/d - potato and salmon, egg and rice, potato and duck, potato and venison
- Royal Canin Select protein - kangaroo and oats, potato and venison, potato and fish
- Royal Canine vegetarian formula
- Blue Buffalo Novel Portein - alligator
What are hydrolysate diets?
proteins broken down in size (<1500 daltons) to reduce allergenicity –> commonly combined with novel protein diets
- feather protein
- chicken liver
- salmon soy
What are some options for feline hydrolyzed protein diets?
- 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
What kind of diet is Purina Pro Plan EL?
proteins are broken down to an amino acid (oligopeptide) level
Are skin support diets acceptable for dietary trials?
NO - neither novel proteins nor hydrolized proteins
- do contain fatty acids for barrier function
- OTC diets NOT reliable, often contaminated
When may grain free diets show improvment in animals with AFRs?
if they are allergic to wheat
- clear association with DCM in dogs
Dog hypoallergenic diets:
Cat hypoallergenic diets:
How long should a hypoallergenic trial extend in dogs and cats?
DOGS - minimum 5 weeks –> 8-12 raises sensitivity
CATS - minimum 6 weeks –> 8 weeks raises sensitivity
AFR:
utricaria
What are keys to a successful dietary trial?
- 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
What treats can be given to animals on a food trial?
- hypoallergenic treats - check ingredient list!
- ice chips
- food part of the trial
When is a positive response to a dietary trial expected?
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
Does a positive dietary response confirm an adverse food reaction?
NO - other disease conditions (atopy) may respond to hypoallergenic diets rich in fatty acids
How are AFRs confirmed? Specific causes?
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
What long-term therapy is recommended for AFRs?
- avoid allergens
- control secondary infections - crucial if these are key manifestations, treat while starting dietary trial
What tends to happen in dogs with environmental and food allergies? How are these dogs identified?
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
What solid data is there of raw meat diets?
significant public health risk –> clear increase in fecal E. coli, Listeria, and Salmonella counts
