Adverse reactions to food. Are they worth investigating

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

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Thanks

Vets South team

Any Questions?

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