Recognition and Assessment of Pain-Related Behaviors in Avian Species: An Integrative Review

The appropriate recognition and assessment of pain in animals is an essential tool that can be used by veterinary professionals, rehabilitators, household caregivers, and others to provide supportive care and analgesia to patients. Although the use of behavioral, postural, and facial changes to recognize pain have been studied in popular domestic species such as dogs (Canis lupus familiaris), cats (Felis catus), and rabbits (Oryctolagus cuniculus), very little is known relative to avian species. The purpose of this article is to provide a literature review comprising structured searches on the topic of avian pain recognition. The emphasis of the searches were based on the behavioral and postural alterations that have thus far been explored. The literature review was performed in the months of August-September 2020 over 5 online databases: MEDLINE/ PubMed, CAB Direct, Biosis, Zoological Record, and Scopus. Additional "snowballing" was incorporated by looking at the references and articles that cited the 126 articles from the initial abstract and full-text screening. Of the 194 full-text articles reviewed, 132 sources of literature were included in the final analysis. From these 132 sources of literature, 31.8% were general review articles in which avian pain behaviors were described irrespective of species, with others being specific to a particular species (chickens 47.8%, turkeys 7.6%, parrots 3.8%, pigeons [Columba livia] 3%, raptors 3%, and "other" 3%-2 on ducks, 1 on emus [Dromaius novaehollandiae], and 1 on Eurasian blue tits [Cyanistes caeruleus]). Pain stimulus varied depending on species, although the vast majority of the pain stimuli involved welfare issues such as beak trimming, limb abnormalities, and keel bone fractures in chickens. Although information regarding this topic remains limited for many avian species, this review provides a more thorough understanding of behavioral indicators of pain in species such as chickens, turkeys, psittacines, pigeons, raptors, and select others. It is the hope that this review will motivate further interest and future analgesia research for the improvement of avian welfare.