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Adverse Food Reactions- are they worth
investigating?
Anthony Chadwick BVSc CertVD MRCVS
The Webinar Vet
In my Liverpool home
• Qualified in 1990
• CertVD in 1995
• Set up The Webinar Vet in 2010
• Sold first opinion practice in 2011
The Story of Rosie McCartney
The Take Home Messages
• Food Allergy/Intolerance is an important cause of
skin disease in dogs and cats
• Food Trials are difficult to do well
• There are often other components contributing to
the itch
Outline of Talk
• Some definitions
• Aetiology and Pathogenesis
• Clinical Signs
• Diagnosis
• Treatment
Definitions
• Adverse reaction to food
• Food allergy reactions
• Food intolerance reactions
Atopic dermatitis and food allergy in humans
• Numerous studies show a clear relationship between food allergens and the development of AD
• Often food allergy seen in infants and young children
• Just under 40% of AD cases will have concurrent food allergy
Aetiology and Pathogenesis
• Not fully elucidated in dogs
• A subset have an IgE mediated food allergy
• Also type III and IV
• However vast majority no immunological cause
found
Aetiopathogenesis
• Puppies who have a poor start to life
• Intestines damaged by virus or worms. Protein allergens can gain access systemically
• Histamine releasing factors continue to be active long after offending allergen removed
• In older dogs sensitisation to an antigen may follow a long refractory period of upto 2 years before clinical signs are present
• In 80% of cases only 1-2 allergens involved
• Common allergens include: beef, soya, chicken,
milk, corn, lamb, wheat, eggs and lamb
How long should you perform a food trial for
• 7 days
• 21 days
• 28 days
• 42 days
• 84 days
What % of your allergic pets have a food
component
• Less than 5%
• 5-10%
• 10-15%
• 15-20%
• More than 20%
How common is Adverse Reaction to Food
• 30% Chamberlain
• 3% Kunkle
• 2% Carlotti
• 13% Saridomichelakis
• 23% Jackson
Clinical Signs
• Food allergy can develop at any age
• I see 2 subsets: very young and 7 plus
• Labradors predisposed
• Abyssinians also
Clinical signs 2
• Non seasonal pruritus
• Recurrent pyoderma
• Similar distribution to atopy
• angioedema
• Otitis
• Concurrent GI signs
Clinical signs in cats
• Miliary dermatitis
• Symmetrical alopecia
• Head and neck pruritus
• Eosinophilic granuloma complex
• Concurrent GI signs in about 30% of cats
Diagnosis
Food Trial!
Food Trialling
• 4-12 weeks required
• Home prepared
• Unusual protein source
• Hydrolysate
• All non seasonal pruritus should be food trialled
Hydrolysed Proteins
Mast cell
degranulation
Allergenicprotein
Histamine
IgE
Sensitised mast cell
Polypeptides (HYDROLYSATES)
Intactprotein
Enzymatichydrolysis
Hydrolysed Proteins
Mast cell
degranulation
Hydrolysed
proteins
No crosslinking – no degranulation
26© Royal Canin SAS 2012. All Rights Reserved.
Extreme hydrolysation:
• Low molecular weight feather
hydrolysate
• In an overall diet analysis, 95%
of the diet is less than 1kDa
EXTREME HYDROLYSIS
Independent analysis of final product
Alternative tests
• Intestinal permeability
• Gastric provocation
• Colonoscopy provocative test
• Intradermal skin test
• Patch test
• Serum IgE testing
Food Challenging
• Feed all old diet back again
• Response usually rapid but upto 3 weeks reported
• Then individual ingredients
• Dairy relapse in 4 days, cereal 8 days(Harvey)
Treat other clinical signs
• Malassezia
• Pyoderma
• Otitis
How much allergen is too much?
• Jackson’s beagle colony reacted to 1g of corn
• Some animals may be less sensitive
Are the diets sufficient for lifelong use?
• Anallergenic
• Hypoallergenic
• Home prepared diet
My plan for non-seasonal pruritus
• Treat infections
• Food and flea trial
• See back in 4 weeks
• Continue food trial if some improvement, possibly skin test
• Food challenge at 8 weeks
• If positive try individual allergens
Vets South offer
• All my topics on slide share and access at The
Webinar Vet
• £1 membership offer
• Access to pet webinars
Upcoming webinars
• Sub plexus flaps
• Cushings disease- The American Perspective
• Glaucoma
• Equine series
• 400 hours of archive
Thanks
Vets South team
Any Questions?
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