HISTOCHEMICAL-STUDY OF CUTANEOUS MUCINS IN HYPOTHYROID DOGS

A dermal mucinoisis, visualized as dermal alcianophilic material, is o ccasionally present in canine hypothyroidism (myxedema). Various histo chemical reactions (alcian blue/periodic acid-Schiff[PAS], alcian blue at pH 2.6, alcian blue at pH 1.0, critical electrolytical concentrati ons with and without dimethylsulfoxide, differential hydrolysis by hya luronidases) were performed on skin biopsies from six dogs (four femal es and two males ranging from 8 to 13 years) affected by hypothyroidis m, all of them presenting dermal mucinosis in hematoxylin and eosin-st ained sections. In these dogs, the only polysaccharidic compound invol ved in the dermal mucinosis was hyaluronic acid. In this study, hyalur onic acid dermal deposits of hypothyroid dogs were significantly diffe rent from those of controls in subepidermal connective tissue and loos e reticular connective tissue but not in periadnexal zones. We recomme nd the combined alcian blue/PAS reaction as a routine technique to ass ess dermal mucinosis in hypothyroid dogs.