Page 1009 - Veterinary Immunology, 10th Edition

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FIG. 30.10 A key contributor to the development of atopic
dermatitis is skin barrier dysfunction. This is influenced by genetic,
climatic, and allergic factors and exacerbated by scratching.

Filaggrin is a filament-associated protein involved in cross-
linking keratin fibers in epidermal cells. It is a major barrier protein
that helps the skin retain fluid. Single nucleotide polymorphisms

(SNPs) within the canine filaggrin gene have been associated with
some forms of canine atopic dermatitis. The importance of filaggrin
in canine atopic dermatitis is unclear. It is possible that filaggrin
defects only account for a subset of canine AD cases, or

alternatively, filaggrin defects are secondary to some other cause of
AD. Likewise, there is no clear evidence as yet that improving skin
barrier function is of clinical benefit in the treatment of atopic dogs.

Infections
The severity of canine AD is influenced by (and influences) the skin

microbiota. The skin microbiota is altered in allergen-induced
canine AD where the lesions have evidence of dysbiosis. This is
associated with a relative increase in Staphylococcus

pseudintermedius. Recurrent staphylococcal skin infections are
associated with canine AD. These staphylococci may release toxins
or superantigens (Chapter 7) that promote skin inflammation. The
skin microbiota also influences expression of the C5a receptor that

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