Sequential Histopathological Changes and Cytokine Expressions in Dogs Naturally Infested with Sarcoptes scabiei Mites

The diagnosis and treatment of canine scabies remain quite challenging as a result of the meddling of the invertebrate mite Sarcoptes scabiei var canis with the immunologic activity of its host.

This study aims to evaluate and better understand the immunologic, histomorphometric, histopathologic changes as well as their relationship in scabies infestation.

Ten healthy dogs were housed with five sarcoptes-ridden dogs. Skin biopsies were then obtained afterwards for 7 weeks into buffered formalin. Sections of obtained biopsies were processed and incubated in IL-4, IL-13, IL-17A and IL-23A antibodies, while the other sections were stained for cellular alterations, quantifications and measurement of tunnel height and diameters. Pearson's product-moment correlation was used to establish the association between the cytokines and the measured tunnel heights and diameters, while Student's t test and one-way analysis of variance were used to test for weekly significant differences in cytokine expressions.

Histopathologic changes and early expression of all studied cytokines, eosinophils and mast cells were pronounced from the second week of infestation. Quite notable was the consistent amount of IL-13 and IL-23A all through the study duration. A dissimilar association was also observed between anti-inflammatory cytokines (IL-4 and IL-13) and pro-inflammatory cytokines (IL-17A and IL-23A). Also observed was the negative relationship between IL-13 and IL-23A as an increase in IL-13 was associated with a decrease in IL-23A. Tunnel height increase was also positively associated with pro-inflammation.

Immunodiagnosis can possibly be achieved with IL-13 and IL-23A expressions, while immunotherapy seems possible with IL-13 cytokine therapy.