Osteoarthritis (OA) is a pathology of great impact worldwide which its physiopathology is not completely known and usually diagnosed by imaging techniques performed at advanced stages of the disease. The aim of this study was to evaluate early serum metabolome changes and identify the main metabolites involved in an inflammatory OA animal model. The study was performed with thirty rats, OA in all animals was induced by intra-articular injection of monoiodoacetate into the knee joint. Blood samples were taken from all animals and analyzed by mass spectrometry before OA induction, and 28, 56 and 84 days following induction. Histological study confirmed OA in all samples. The results of this study allow the identification of several changes in the serum metabolome over time, including organic acids, benzenoids, heterocyclic compounds and lipids at T28, organic acids at T56 and lipid classes at T84. We conclude that OA induces serological changes in the metabolome and, more specifically, 18 metabolites which could serve as potential biomarkers. However, it was not possible to establish a relationship between the identified metabolites and the time at which the samples were taken. Therefore, these findings should be confirmed in future OA studies.