Surgical sterilisation to manage free-roaming dog populations is widely used in many countries. However, few studies have examined optimal postoperative pain management regimens at low-resource, high-throughput veterinary clinics. The aim of this study was to examine the efficacy of two intravenous analgesic regimens, preoperative administration of meloxicam and tramadol, or meloxicam alone, in free-roaming dogs undergoing sterilisation. A total of 125 dogs were included, with 64 dogs in the meloxicam-tramadol arm and 61 dogs in the meloxicam-only arm in a non-inferiority study design. Pain levels in sterilisation surgery patients were assessed at four time points after surgery using the Colorado State University Canine Acute Pain Scale, a Visual Analogue Scale and a modified version of the Glasgow Composite Measure Pain Scale - Short Form. Non-inferiority was supported for each of the main scoring outcomes using non-inferiority margins of 0.5, 5 and 0.8, respectively. One dog from the meloxicam-tramadol group and four dogs in the meloxicam-only arm required rescue analgesia, with no difference between groups (P=0.21).The study demonstrated that meloxicam was effective in controlling postoperative pain in a high proportion of dogs. The addition of tramadol alongside meloxicam treatment was not found to be of clinical benefit.