Food Allergy Flashcards
Two stems off of Food Allergies are
Immunologic:
Type: I, III, or IV
Non-immunologic:
Food intolerance
Dietary indiscretion
Food Allergy
Pathogenesis
Not completely understood
Exposure to allergens
Development of immune response (oral tolerance)
Activation of immunogenic pathway
M cells in GI tract capture antigen –> present to antigen presenting cells in Peyer’s Patch –> travel to lymph nodes –> IgA
Involves:
Histamine
Proteases
Chemotactic factors
What disease is thought to predispose animals to food allergies?
GI disease
Food Allergy
Antigen Types
Dog
10,000-30,000 Daltons
Beef Chicken Dairy products Wheat Soy Lamb
Food Allergy
Antigen Types
Cat
10,000-30,000 Daltons
Beef Dairy products Chicken Fish Lamb
Food Allergy
Clinical Features
Dog
Usually less than 1 year of age
Non-seasonal pruritus
Affects: Ventral hairless area Face Feet Peri-anal
Think: ears and rears
Food Allergy
Secondary Issues
Dog
Otitis (recurring) Recurrent pyodermas GI signs Vasculitis Urticaria Erythema multiforme (target lesions; suggestive of hypersensitivity) - antigen driven
Food Allergy
Clinical Features
Cats
Age: 4-5 years
Pruritus (head and neck)
Reaction Patterns:
Miliary dermatitis
Eosinophilic granuloma complex
Pruritus
DfDx
Atopic dermatitis (diagnosis of exclusion) Drug reactions Contact hypersensitivity Flea allergy Scabies Yeast dermatitis
Diarrhea
DfDx
GI parasites
IBD
PLE
GI lymphoma (older patients)
Food Allergy
Diagnosis
Elimination diet and provocative exposure
Will take time
Trials: 3-12 weeks (6-8 recommended) with a STRICT regimen
Allergen avoidance
Food Allergy
Allergy tests
Intradermal skin testing
Allergen-specific serum IgE
Patch testing
All are NOT effective
Food Allergy
Medication Causes
Flavoring additives!
Vitamins Supplements Prevenatives: heartworm, flea Arthritis medication Urinary incontinence medication Dental products
Must keep this in mind during diet trial
Pruritus Rx
Corticosteroids; may not work which further supports food allergy
Apoquel
Cytopoint
Note: still must determine underlying cause of pruritus
Types of Diets Used for Diagnosis
Home-made; gold standard but must be done through nutritionist monitoring
Can make it for the individual (control)
Novel protein diets
Hydrolyzed
Novel Protein Diets
Rabbit Kangaroo Venison (beef) Duck Fish \+/- pork
Keep in mind taxonomic relationships (ex. duck and poultry)
Look at the ingredients some claim to be novel protein diets but the third-fifth ingredient is actually chicken or beef
If losing weight may need to switch diet
Hydrolyzed Diet
What is it?
Peptide bond in amino acid chains are broken to generate smaller fragments (reduces allergenicity and improves digestibility)
Not complete hydrolyzed b/c decreases palitability
Molecular weight less than 10,000 Daltons; less likely to be targeted by immune system
Protein does not have to be a novel source
May still not work for some animals
Hydrolyzed Diets
Exmamples
Royal Canin:
Ultamino (duck feathers); 99% peptides are <6,000 Daltons which is promising
PS (potato and soy)
HP (soy/brewers rice)
Hills:
z/d and z/d ultra
Purina:
HA (soy)
Food Allergy
Grain Free
Does not help with food allergy because food allergy is often due to protein not the grain
Marketing scheme
Corn is not allergenic
Grain actually provides nutritious source of carbs and essential amino and fatty acids for skin
OTC Allergy Foods
What to be wary of
CHECK THE INGREDIENTS
May not be as they claim
Studies have shown these diets may contain protein snot listed in ingredient list!
Cross-contamination also common; not required to clean machine in-between switching from one food to the next
Also, transport vehicles/containers are not cleaned
Food Allergy
Diagnostic Approach
History
Pruritus? (should be yes) Age of onset (young) Seasonal (environmental) vs Non-seasonal (food) Infections (skin/ear) GI symptoms? (yes)
Food Allergy
PE findings
Pyoderma
Otitis
Food Allergy
Pyoderma Rx
Must treat for 3-4 weeks with re-check
First tier: Cephalexin Simplicef Convenia (repeat in 14 days) Clavamox
Only use second tier with C/S results
Food Allergy
Otitis Rx
May see bacteria and/or yeast
q12 hours for 10-14 days
Otomax
Miconazole/Dex
Osurnia
