Measurement of acute phase proteins (APPs) has now become part of routine laboratory testing for companion animals in many areas of the world. As useful markers of infectious and inflammatory diseases, APPs have been shown to have value in many areas, including health assessments, prognosis, herd health, and animal welfare. The increased use of all acute phase reactants in domesticated animals has been paralleled by an increase in research detailing the measurement and application in non-domesticated mammals. There are many challenges for future research in this still-developing field.http://wileyonlinelibrary.com/journal/vcp2023-02-26hj2023Centre for Veterinary Wildlife StudiesCompanion Animal Clinical Studie