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An Urban Experience
M. Chandler1
1Vets Now Referrals, Clinical Nutrition, Lasswade Midlothian, United Kingdom
The Nutritionist View
Vets Now Referrals 123-145 North Street, Glasgow UK G3 7DA
One of the most important functions of the skin is as
a barrier. It prevents water loss (inside-outside barrier) and protects the body from the environment (outside- inside barrier). The barrier function is dependent on the stratum corneum (SC). It has been suggested that atopic dermatitis (AD) is associated with a defective barrier function. One study which assessed barrier function
with transepidermal water loss (TEWL, the volume of water passing from inside to outside of the body through the upper epidermal layers) found a higher TEWL in
dogs with AD vs controls1. Treated AD dogs had lower TEWL compared to non-treated, suggesting skin barrier function can be improved by treatment. Nutrition is important to ensure the healthy skin barrier2. It is not
fully known whether nutritional modification can improve the skin barrier function in dogs and cats with disease, although there is some promising research in this area.
Nutrient deficiencies and skin disease
The skin is the largest organ in the body with a high turnover rate, thus, several nutrient deficiencies can result in skin problems3-7, including protein and some amino acids, omega 6 essential fatty acids, trace elements, lipid soluble vitamins and B vitamins. These deficiencies are unlikely in healthy pets fed complete and balanced diets. Unbalanced homemade diets can result in all of these deficiencies.
Protein: Hair is 95% protein and certain amino acids are especially important for healthy hair, e.g. methionine, cysteine, and tyrosine. Protein deficiency can cause thin, dull brittle hair, and tyrosine deficiency can cause a loss of dark hair pigment.
Zinc: Zinc dependent metalloproteinases are involved
in keratinocyte migration and wound healing. Several syndromes are associated with zinc deficiency, including Syndrome I in Huskies and Malamutes associated with
zinc malabsorption and Syndrome II in puppies fed a zinc deficient diet.
Fat Soluble Vitamins
Vitamin A deficiency can cause skin scaling, poor hair coat, and alopecia. Vitamin A is very important for
all epithelia and its deficiency results in altered skin barrier function but there is no data to support its supplementation to help skin barrier.
Vitamin E, an antioxidant, protects fatty acids (including those in the SC) from damage. Deficiency can result in pansteititis (e.g. cats fed a raw fish diet) resulting in firm painful swellings due to inflammation from adipose tissue perioxidation. One study found dogs with atopy had lower plasma vitamin E and that supplementation (8.1 IU/kg q24 hours for 8 weeks) improved the subjective pruritus score; however, it is unknown if this relates to improvement of skin barrier function8.
B vitamin deficiencies
Deficiencies of biotin, riboflavin niacin and pyridoxine may be associated with skin disorders. One study found a positive effect on TEWL of healthy dogs with
a diet supplemented with pantothenic acid, niacin, choline, inositol, and histidine. These nutrients showed in vitro stimulation of ceramide synthesis in canine keratinocyes6. One small study with Labrador puppies fed this combination of nutrients suggested that it could help reduce itch when fed for one year9. However, there is very little data on the effects of supplementing these nutrients separately and no data on how does this combination work to improve skin barrier function.
Essential fatty acids
Essential fatty acids (EFA) are fatty acids from the omega 6 and 3 families. Linoleic acid is an omega 6 EFA that is incorporated in the ceramides of the SC4 and deficiency results in dry, coarse skin. High fat diets or vegetable oil supplements like corn oil can improve hair coat quality
in dogs. Omega 6 EFA are more potent than omega 3s for skin barrier function Oral supplementation with EFA (especially linoleic acid) can improve ceramide synthesis in dogs, although the studies are still scarce and more data is needed to confirm its effect and the appropriate route, dose and composition of the treatment5.
Omega 3 fatty acids, e.g. ecosapentanoic and docosahexaenoic acid, result in cytokine production with less inflammatory characteristics than omega-6 EFAs and may decrease pruritus in dogs10and skin inflammatory responses in cats11.

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