Small animal clinical nutrition - dermatoses and allergies Flashcards
Any metabolic or other disease which affects the ability of animals to digest, absorb or use nutrients may cause
secondary nutrient imbalance and can present as a skin conditions (among other signs).
Adverse reactions to foods are often divided into…
immune mediated or non-immune mediated
immune mediated or non-immune mediated adverse food reactions can each be called..?
immune mediated = food allergy/hypersensitivity
non-immune mediated = food intolerance
what percentage of inflammatory skin problems are due to food reactions?
15%
Food sensitivity =
Food intolerance =
Food sensitivity = the immune-mediated reaction to a food ingredient.
Food intolerance = non-immune mediated reaction to food ingredients.
Describe food allergens.
- There are antigens (proteins or even haptens) in the food that are able to illicit specific allergic reactions.
- There is a minimum molecular size that is able to induce IgE production (capacity of gut mucosa to “absorb” particle).
- Human allergens are almost exclusively glycoproteins with a molecular weight of 10-70 kDa.
- In dogs, very few true allergens have been identified and their molecular weight is over 20kDa.
- e.g. most commonly Beef, soy, chicken, eggs, dairy products, wheat, corn etc.
molecular weight of food allergens
between 10-70 kDa, mostly over 20kDa in animals.
- Human allergens are almost exclusively glycoproteins with a molecular weight of 10-70 kDa.
- In dogs, very few true allergens have been identified and their molecular weight is over 20kDa.
Most common true food allergens to affect dogs and cats?
e.g. most commonly Beef, soy, chicken, eggs, dairy products, wheat, corn etc.
Multiple forms of food hypersensitivity are possible and ?% of dog are allergic to more than one of the food components.
Multiple forms of food hypersensitivity are possible and 35-48% of dog are allergic to more than one of the food components.
- Trans reactions are possible , but they are not diagnosed in animals.
- NB Possible cross-reactivity for meat originating in taxonomically similar species (turkey, duck, chicken).
1st step to diagnosis of adverse reactions to food / food allergy.
Exclude all other causes of allergic reactions first. Such as Atopy, Flea bite allergy, Sensitivity of medicinal products etc.
A complete nutrition overview is critical at all levels of diagnosis and control.
Elimination diet following by controlled food trials next.
Intradermal and blood allergy tests are
have low reliability in diagnosis of
food allergies in dogs and cats even though are common in people.
Describe Elimination diets.
Feed only a single protein source and single carb source - a kind that the animal has never had before.
Introduce this elimination diet gradually over minimum 4 days.
Once the animal has been eating only the novel protein, improvement of clinical signs should be seen in 3-10 weeks.
The diet may be fed up to 12 weeks, so even after resolution of clinical signs.
What does the “ascertain harmful components” portion of food trials involve?
The nutritional components that are suspected to cause the adverse reaction are added back to the elimination diet, one by one and the animal is monitored for allergic response.
It is paramount that food components are introduced one at a time so as to discern which one is causing the reaction!
Describe “challenging” for confirmation of food allergy diagnosis.
After the animal has been on the novel protein diet for 10-12 weeks and clinical signs have resolved - introduce the animal back to its original food.
If itching or other signs reoccur within 4 hours to 4 days of reintroduction of old food, it confirms the diagnosis of food intolerance.
An ideal elimination diet has to: (5)
Contain limited numbers of new, highly digestible proteins (or based on
hydrolyzed proteins).
Have lower protein content than maintenance foods. (low protein content is really only useful in case of non-allergic reactions (like intolerances) cause if you’re truly allergic then the amount will not matter!)
Avoid supplements and vasoactive amines (e.g. Histamine).
Be nutritionally adequate to life stage and condition of animal.
Contain omega-3 (anti-inflammatory effect) and vitamins (against oxidative stress).
