Dog faces exhibit anatomical differences in comparison to other domestic animals

Burrows, Anne M.; Waller, Bridget M.; Omstead, Kailey M.; Rogers-Vizena, Carolyn R.; Mendelson, Bryan C.

doi:10.1002/ar.24507

Cited by 8 publications

(3 citation statements)

References 59 publications

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“…In the lower muscle group, the digastric muscle in its posterior belly, the buccinator , the orbicularis oris, zygomaticus, mentalis, caninus, levator labii maxillaris , and levator nasiolabialis originate movements in the ventral edge of the jaw to push it down (AU25), open the dog’s mouth (AU17), deepen the nasolabial fold (AU11), or tighten the corners of the lips (AU27) [ 57 , 58 , 59 ]. Burrows et al [ 60 ] mention that the marked anatomical differences in the faces of canids hinder reading their facial expressions because dogs have more than 20 facial movements; this is in comparison with other species, such as the chimpanzee or the cat, which only present 14 and 15 actions, respectively [ 61 , 62 ].…”

Section: The Anatomy Of Facial Expressions In Dogsmentioning

confidence: 99%

“…The tension of the muscles of the face, lips, orbital region, and flattening of the ears are commonly recognized in animals [ 2 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 147 , 148 , 149 , 150 ]. This system has been adapted as a veterinary clinical tool (called Grimace Scales) to identify pain in species such as equines [ 142 ], chimpanzees [ 60 ], macaques [ 143 ], sheep [ 8 ], rabbits [ 144 ], ferrets [ 145 ] and rats [ 33 ].…”

Section: Changes In Facial Expressions Related To Painmentioning

confidence: 99%

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Current Advances in Assessment of Dog’s Emotions, Facial Expressions, and Their Use for Clinical Recognition of Pain

Mota-Rojas

Marcet-Rius

Ogi

et al. 2021

Animals

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Animals’ facial expressions are involuntary responses that serve to communicate the emotions that individuals feel. Due to their close co-existence with humans, broad attention has been given to identifying these expressions in certain species, especially dogs. This review aims to analyze and discuss the advances in identifying the facial expressions of domestic dogs and their clinical utility in recognizing pain as a method to improve daily practice and, in an accessible and effective way, assess the health outcome of dogs. This study focuses on aspects related to the anatomy and physiology of facial expressions in dogs, their emotions, and evaluations of their eyebrows, eyes, lips, and ear positions as changes that reflect pain or nociception. In this regard, research has found that dogs have anatomical configurations that allow them to generate changes in their expressions that similar canids—wolves, for example—cannot produce. Additionally, dogs can perceive emotions similar to those of their human tutors due to close human-animal interaction. This phenomenon—called “emotional contagion”—is triggered precisely by the dog’s capacity to identify their owners’ gestures and then react by emitting responses with either similar or opposed expressions that correspond to positive or negative stimuli, respectively. In conclusion, facial expressions are essential to maintaining social interaction between dogs and other species, as in their bond with humans. Moreover, this provides valuable information on emotions and the perception of pain, so in dogs, they can serve as valuable elements for recognizing and evaluating pain in clinical settings.

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Section: The Anatomy Of Facial Expressions In Dogsmentioning

confidence: 99%

Section: Changes In Facial Expressions Related To Painmentioning

confidence: 99%

Current Advances in Assessment of Dog’s Emotions, Facial Expressions, and Their Use for Clinical Recognition of Pain

Mota-Rojas

Marcet-Rius

Ogi

et al. 2021

Animals

View full text Add to dashboard Cite

show abstract

“…A major challenge in identifying standardised facial expressions in dogs concerns the morphological diversity of their heads 20 , 21 and overlying dermal structures, such as the inclusion of permanent wrinkles in some breeds. To identify facial emotional expressions in dogs, Caeiro et al 18 applied DogFACS to assess the spontaneous response of individuals of different breeds and mixes in naturalistic emotional settings using online videos.…”

Section: Introductionmentioning

confidence: 99%

Explainable automated recognition of emotional states from canine facial expressions: the case of positive anticipation and frustration

Boneh-Shitrit

Feighelstein

Bremhorst³

et al. 2022

Sci Rep

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In animal research, automation of affective states recognition has so far mainly addressed pain in a few species. Emotional states remain uncharted territories, especially in dogs, due to the complexity of their facial morphology and expressions. This study contributes to fill this gap in two aspects. First, it is the first to address dog emotional states using a dataset obtained in a controlled experimental setting, including videos from (n = 29) Labrador Retrievers assumed to be in two experimentally induced emotional states: negative (frustration) and positive (anticipation). The dogs’ facial expressions were measured using the Dogs Facial Action Coding System (DogFACS). Two different approaches are compared in relation to our aim: (1) a DogFACS-based approach with a two-step pipeline consisting of (i) a DogFACS variable detector and (ii) a positive/negative state Decision Tree classifier; (2) An approach using deep learning techniques with no intermediate representation. The approaches reach accuracy of above 71% and 89%, respectively, with the deep learning approach performing better. Secondly, this study is also the first to study explainability of AI models in the context of emotion in animals. The DogFACS-based approach provides decision trees, that is a mathematical representation which reflects previous findings by human experts in relation to certain facial expressions (DogFACS variables) being correlates of specific emotional states. The deep learning approach offers a different, visual form of explainability in the form of heatmaps reflecting regions of focus of the network’s attention, which in some cases show focus clearly related to the nature of particular DogFACS variables. These heatmaps may hold the key to novel insights on the sensitivity of the network to nuanced pixel patterns reflecting information invisible to the human eye.

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Evolutionary divergence of facial muscle physiology between domestic dogs and wolves

Burrows,

Smith,

Downing

et al. 2024

The Anatomical Record

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Domestic dogs (Canis familiaris) are descended from gray wolf (Canis lupus) populations that inhabited Western Europe and Siberia. The specific timing of dog domestication is debated, but archeological and genetic evidence suggest that it was a multi‐phase process that began at least 15,000 years ago. There are many morphological differences between dogs and wolves, including marked divergence in facial muscle morphology, but we know little about the comparative physiology of these muscles. A better understanding of comparative facial muscle physiology between domestic dogs and gray wolves would improve our conceptual framework for the processual mechanisms in dog domestication. To address these issues, we assessed the myosin profiles (type I and type II) from the zygomaticus and orbicularis oris muscles of 6 domestic dogs and 4 gray wolves. Due to small sample sizes, statistical analyses were not done. Results reveal that sampled domestic dogs have almost 100% fast‐twitch (type II) muscle fibers while gray wolves have less than 50%, meaning that dog faces can contract fast while wolf faces are able to sustain facial muscle contraction. Sample sizes are limited but the present study indicates that dog domestication is associated with not only a change in facial muscle morphology but a concomitant change in how these muscles function physiologically. Selective pressures in the development of communication between dogs and humans using facial expression may have influenced this evolutionary divergence, but the paedomorphic retention of barking in adult dogs may have also played a role.

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Dog faces exhibit anatomical differences in comparison to other domestic animals

Cited by 8 publications

References 59 publications

Current Advances in Assessment of Dog’s Emotions, Facial Expressions, and Their Use for Clinical Recognition of Pain

Current Advances in Assessment of Dog’s Emotions, Facial Expressions, and Their Use for Clinical Recognition of Pain

Explainable automated recognition of emotional states from canine facial expressions: the case of positive anticipation and frustration

Evolutionary divergence of facial muscle physiology between domestic dogs and wolves

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