Behaviors associated with formalin-induced pain in the Japanese quail (Coturnix coturnix japonica)

The present study aimed to investigate behaviors associated with formalin-induced nociception in the Japanese quail (Coturnix japonica). The tarsometatarsus region of the male quail's foot (shank) was injected with 40µl of formalin (0.3, 0.6, and 0.9%) solutions or normal saline. Two distinct nociceptive behaviors that is injected foot lifting and flinching/shaking behaviors were recorded over 45 minutes. Also, unstimulated preening, eye closing, and chamber wall pecking behaviors were recorded during the observation period. Subcutaneous injection of formalin 0.6 and 0.9% significantly increased the foot lifting activity in the 0-5 minutes (acute phase) and 15-45 minutes (inflammatory phase) after administration. But the injection of formalin 0.3% significantly increased foot lifting activity only in the acute phase. In the other recorded behaviors, we did not find this biphasic time course pattern. All formalin concentrations induced significant foot flinching/shaking activity only in the acute phase. Subcutaneous injection of formalin 0.9% but not 0.6 and 0.3% significantly increased the duration of eye closure behavior between 20-45 minutes after administration. Injection of all formalin concentrations caused a significant decrease in the unstimulated preening activity between the period of 10 to 45 minutes after administration. Injection of all formalin concentrations caused a significant decrease in the observation chamber wall pecking activity between the period 30 to 45 minutes after administration. These results suggest that the quail formalin test can be considered a relevant, sensitive, and specific technique that helps researchers to use it in the determination of the neurobiology and pharmacology of nociception in the avian species.