Skin protects the body by mediating various immune responses against exogenous substances including bacteria, fungi, and viruses, in addition to its predominant role as a physical barrier. Despite the significant protection offered via various mechanisms, bacterial infection of the skin is one of the most common skin diseases in veterinary medicine. This study demonstrated the structural and immunological changes in the skin during infections with Pseudomonas aeruginosa and Staphylococcus pseudintermedius using skin explants from four healthy beagles. Skin structure was generally well preserved in uninfected controls, but defects in skin structure, including injury of keratinocytes and dermal–epidermal junctional disruption, were identified when skin explants were exposed to P. aeruginosa and S. pseudintermedius. On exposure to P. aeruginosa, marked linear cleft formation was noted along with acantholysis along the basal layer after 24 hours of culture. In addition to the defects in the skin structure, mRNA expression levels of the AMPs cBD103 and S100A8 were decreased, which was confirmed by immunohistochemical staining. Taken together, these results suggest that our ex vivo canine skin model is a research tool for investigating bacterial skin infections in dogs.

Canine atopic dermatitis (CAD) is an allergic skin disease with characteristic clinical features associated with immunoglobulin E (IgE) antibodies. Identification of the causative allergens is the diagnostic goal, which is essential to treat and manage CAD patients. CAD is commonly associated with environmental allergens surrounding the patients. For this reason, it is important for diagnostic tests to select allergens that are related to the environment of each country and each province. There are two main allergen-specific tests, serological IgE test (SAT) and intradermal skin test (IDT). SAT did not show direct cutaneous reaction but did show serological reaction against allergens. However, SAT is simpler and more convenient than IDT in small animal practice. In this study, we selected domestically prevalent allergens for SAT, including 60 food allergens and 60 inhalant allergens, and tested eight dogs tentatively diagnosed with CAD based on Favrot’s criteria. Furthermore, IDT was performed on four dogs from the SAT group for comparison of SAT and IDT, and the results were very similar. In SAT, four types of mites (Bloomia tropicalis, Glycophagus domesticus, Euroglyphus maynei, and mite mixture 1 Korea; house dust mites), four types of molds (Botrytis cinerea, Alternaria alternata, mold fungi mixture 11, mold fungi mixture), and one type of pollen (tree pollen mix 3 Korea) induced a reaction in more than half of dogs tested. In IDT, all four dogs reacted positively to Dermatophagoides farinae, and three reacted positively to Dermatophagoides pteronyssinus and house dust. The mean agreement rate between SAT and IDT in this study was 76.3%. This is the first trial to apply local allergens for SAT in Korean veterinary medicine, and it might play an important role for diagnoses and management of animal allergic diseases.