Canine C-reactive Protein Validation of Two Automated Canine-specific C-reactive Protein Assays and Studies on Clinical and Research Applications

C-reactive protein (CRP) is a sensitive and specific marker of systemic inflammation in dogs, valuable for diagnosing and monitoring inflammatory diseases. The use of CRP in canine medicine has however been hampered by the lack of automated assays optimized for measuring CRP in this species. The need for improved CRP assays was the reason for initiating the current project, with the goal to generate automated, canine-specific CRP tests that could reliably measure serum CRP over the whole concentration range expected to occur in dogs. Two different assays were developed for this purpose. One was designed for routine diagnostic testing, and one was a high-sensitivity CRP test intended for research. Method validation studies were performed, demonstrating that both tests met the predefined quality criteria. Using the two novel CRP tests, it was possible to reliably measure serum CRP concentrations in the range of 0.5-1200 mg/l. After successful termination of the validation studies, the CRP assays were used in clinical research studies. C-reactive protein concentrations were measured in dogs with pyometra undergoing ovariohysterectomy, to evaluate how surgical treatment affected degree of systemic inflammation in these patients. Two other studies were performed to evaluate the usefulness of CRP as a diagnostic test. C-reactive protein concentration was found to discriminate well between dogs with suppurative arthritis and dogs with osteoarthritis, whereas measurement of CRP was not efficient for diagnosing late postoperative bacterial infections after orthopaedic surgery because these infections often did not elicit a systemic inflammatory response. In conclusion, two novel automated canine-specific CRP assays were developed and validated with satisfactory results. The tests showed high practicability for measuring CRP in samples from clinical research studies. Availability of these assays will facilitate the use of CRP as a routine diagnostic test in veterinary medicine, and can improve quality in research on canine inflammatory diseases.