Adequate pain control is an essential part of therapeutic intervention in acute and chronic pain for all animals, including birds. Multimodal analgesia through combined systemic administration of opioids and non-steroidal anti-inflammatory drugs (NSAIDS) is considered more effective than administration of either drug class individually and although this approach is clinically applied to birds, it has not been experimentally evaluated. NSAIDS are characterized by their anti-inflammatory effects on peripheral tissues, and also have central antinociceptive effects. Opioids exert their actions by binding to specific membrane receptors that are distributed in neurologic tissue involved in transmission, modulation and sensation of pain. Opioids provide central analgesia at the spinal cord and the brain, provide peripheral analgesia, and also reduce peripheral inflammation. Our study measured the attenuation of tonic pain in parrots (n=19) following administration of a long-acting opioid agonist and an NSAID. The four treatment groups, in a complete cross-over study, were as follows:
1. Liposome encapsulated butorphanol (LEBT: 15 mg/kg SC once)
2. Carprofen (2 mg/kg IM BID every 12 h)
3. LEBT plus carprofen in combination
4. No treatment (control)
Experimental monoarthritis was induced in each Hispaniolan parrot (n=19) by injection of 0.1 ml 8% urate crystals into the intertarsal joint. An incapacitance meter, adapted to perching, measured the weight load of each limb simultaneously. Weight bearing was evaluated prior to monoarthritis, and at 2, 6, 26, 30, 50, 54, 74, and 98 hours following interarticular injection of urate solution. When compared to baseline values, weight bearing was significantly decreased on the limb with monoarthritis at 2, 6, 26 and 30 hours. Using statistical analysis to compare the four groups, those treatments that included butorphanol were significantly different from the control birds, while the carprofen-treated birds were not significantly different from the controls.