The invention relates to an oily composition of a non-steroidal anti-inflammatory agent (NSAIA) for parenteral administration with at least one micronized NSAIA, having an acid function and a biocompatible oily vehicle, such that said NSAIA is in the form of a free acid and said composition does not contain any added liquid agent that can solubilize said NSAIA. The invention also relates to the veterinary use thereof.