The functional significance and welfare implications of chewing in dogs (Canis familiaris)

Rimini Quinn ^1* Sophie Masters ¹ Melissa Starling ¹ Peter John White ¹ Kathryn Mills ¹ David Raubenheimer ² Paul Mcgreevy ¹

• ¹ School of Veterinary Science, Faculty of Science, The University of Sydney, Camden, Australia
• ² Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales, Australia

Dogs chew on both nutritive and non-nutritive items as part of food acquisition and ingestive behaviour, self-care, and during social interactions. Various definitions help to distinguish chewing from related oral activities such as gnawing, masticating, and biting. Surprisingly, despite chewing being a ubiquitous behaviour in dogs, it is unclear how relevant the activity is for a dog’s comfort, health, and telos. In addition, the risk of dental fractures or other injury may incline veterinarians to advise against feeding bones to dogs. This article explores the literature on chewing in dogs using the ethological framework of “Tinbergen’s Four Questions,” and the Five Domains framework for animal welfare assessment. Evidence is sourced from wild and domestic canids, as well as more broadly from human and animal models where there are physiological or biological processes in common. Chewing appears to promote biological fitness, with benefits arising from dental and oral hygiene, digestive health, bone strength, psychological health, and stress management. Furthermore, the article discusses the evolutionary importance of chewing, the mechanisms that influence bite force, chew rate and morphology, and development of chewing throughout an individual’s life from primary teeth eruption until senescence. Application of the Five Domains of welfare framework assists in identifying the impact of chewing, or lack thereof, on a dog’s welfare. What most appeals to dogs when selecting items to chew is strongly influenced by the item’s odour, followed by its taste and mouthfeel. Macronutrient proportions may play a role in food preferences, and these are likely to influence the selection of chewable items. Lack of preferred items to chew may lead to the redirection of chewing towards less appropriate items, such as non-food chews which may be harmful to dentition or the gastrointestinal tract (GIT), the adoption of other oral behaviours, or reduce their contentment by impeding telos. Overall, chewing positively impacts a dog’s physical and psychological health, thus its welfare, and appears important as a regular component of a dog’s daily life. The significant benefit from chewing needs to be evenly evaluated against the risks.