Evaluation of C-reactive protein as an inflammatory marker of pemphigus foliaceus and superficial pyoderma in dogs

Background - C-reactive protein (CRP) is a major acute phase protein in dogs and may be an inflammatory marker of autoimmune diseases. Hypothesis/Objectives - To measure pre- and post-treatment CRP levels in dogs with superficial pyoderma (SP) and pemphigus foliaceus (PF) compared to normal dogs; to evaluate possible correlation between CRP values, indirect immunofluorescence (IIF), and pemphigus foliaceus extent and severity index (PEFESI) scores. Animals - Fifty nine dogs divided into three groups: Group I (control, n = 31), Group II (SP, n = 14) and Group III (PF, n = 14). Methods - CRP levels were measured in Group I dogs. Skin biopsies of Groups II and III dogs were obtained for histopathological examination. In Group II dogs, CRP levels were measured at days 0, 15, 30 and 60. In Group III dogs were evaluated by PEFESI, IIF and CRP levels at days 0, 15, 30, 60 and 90. Results - Group III showed a higher median CRP (37.4 mg/mL) compared to the other groups (Group I, CRP 2.9 mg/mL, P < 0.0001; Group II CRP 3.8 mg/mL, P = 0.008). There was no significant difference in CRP levels between groups I and II. IIF titres and CRP levels decreased in most cases of PF with clinical improvement. Dogs with CRP >10.6 mu g/mL were 5.5 times more likely to have PF than SP. There was a strong positive correlation between CRP values and PEFESI and a weak positive correlation between CRP values and IIF titres. Conclusion and clinical importance - CRP levels are increased in dogs with PF and exceed levels found in most dogs with SP.