2. Animals Live as Dynamically Interacting Whole Entities
Each sentient animal is a living embodiment of dynamically unified and integrated forms, functions, behaviours and related experiential capacities which are unique to its species and manifest in combinations that evolved to secure its survival within particular environments. Each such animal therefore exhibits biotic coherence as a whole entity and it is argued here that this should not be compromised for trivial reasons.
2.1. Internal and External Functional Interactivity and Sensory Capacities
Internally there is widespread interactivity where the operation of each organ system of the body directly or indirectly affects or depends on the operation of all other organ systems, and where their functions combine to maintain stable conditions inside the body. Interactions with the environment require inputs from externally directed sense organs, for example, for touch, temperature, taste, smell, hearing and sight. One or more of these common sensory modalities may exhibit exaggerated functional specialisation [15
], thus enabling the affected species to successfully engage behaviourally with otherwise insurmountable challenges posed by their ecological niche.
Examples include the exaggerated acuity of sight in eagles [16
], smell and hearing in dogs [17
], and sight, hearing and smell in cats [21
]. Other such evolved capacities include the rare sensory modality of ultrasonic echolocation that aids toothed whales, dolphins, some bats, and swifts to find their way in low light-intensity environments [23
], the specialised receptors possessed by sharks and rays that enable them to detect weak electromagnetic fields generated by living prey [24
], and the unusual chemical sensitivity of the forked tongue in reptiles that confers on them heightened abilities to identify prey, recognize kin, choose mates, locate shelters and follow trails [26
Internal functional stability is therefore dynamically maintained in the face of ever-changing external circumstances. This provides a responsive functional platform that enables animals to successfully interact behaviourally with their physical, biotic and social environments in ways which, overall, are unique to each species. Wild dogs, wolves, dingoes, Indian pariah dogs and other canidae provide good examples of such environmentally focused behavioural interactions, as well as their capacity to communicate with each other.
2.2. Canine Behaviours That Involve Communication
Wild canidae usually live in packs and engage in a wide range of behaviours many of which depend upon communication. These behaviours variously include, but are not limited to the following [28
]: exploring and/or monitoring key features of their environment such as the location of water, prey, other food sources, resting areas, den sites and surveillance points; hunting and scavenging for food as a pack or individuals; establishing territorial boundaries; responding defensively to threats from non-pack animals; operating within the pack hierarchy; bonding with pack members; nurturing and protecting young; playing; and engaging in sexual activity. Although living in quite different circumstances, elements of some of these “wild” behaviours appear to be reflected in the interactions of domestic dogs with each other and with people [30
], and those interactions clearly demonstrate communication capacities that utilise different sensory modalities [31
2.3. Sensory and Behavioural Elements of Canine Communication
Dogs as social animals are well known to possess rich communication systems that support their complexly interactive lives [21
]. All major sensory modalities are involved, but especially smell, taste, hearing and sight, and combinations of cues supplied by two or more of these senses potentially increase the range and quality of the information communicated [21
]. The following descriptions of canine sensory involvement in behavioural expression, derived from numerous sources [21
], are provided to give wider insights into the holistic integration of body form, function, sensory capacities and affective-behavioural dynamics. However, note that these examples are limited and general, and are not intended to address nuanced distinctions of behavioural interpretation (e.g., [45
]). Moreover, to simplify the descriptions they have been separated according to single sensory modalities, whereas in reality two or more would usually provide cues simultaneously.
Smell and taste detect chemical signatures that issue from various areas of the body, particularly the mouth and anogenital area, and are present in urine and faeces. They can signal when a dog is aggressive, fearful or confident, and indicate its sex, age and, if female, whether she is on heat, pregnant or has recently given birth.
Hearing detects howls, barks of different types, growls, whines, whimpers, screams, yawns, sighs and other vocal signals. These variously indicate emotions such as excitement, playfulness, confidence, contentment, relaxed greeting, surprise, alarm, threat, anxiety, fear, panic, aggression, loneliness and others, and may also give a broad indication of the levels of some of these experiences.
Vision is for observing and responding to overt and subtle behavioural cues in different combinations. The cues and what they may indicate include, but are not limited to the following:
Eye gaze—e.g., averted eyes, brief glances and blinking may be signs of placation; assertive direct eye-to-eye contact may indicate threat.
Ear position—e.g., ears slightly back and slightly splayed may indicate uncertainty; ears back, flat against the head may indicate anxiety; ears erect or slightly forward may indicate alert, focused attention.
Mouth shape and tongue—e.g., relaxed open mouth exposing rear teeth, i.e., “smiling”, may signal a relaxed/calm dog; mouth relaxed, slightly open, tongue slightly visible may indicate a dog at ease; mouth closed, no teeth or tongue visible may indicate calm focused attention; fleeting lip or nose licking may indicate unease, discomfort or nervousness; lips curled or lifted to expose teeth and perhaps gums may issue a warning or threat to another; lips retracted, snarling with mouth open and teeth bared may indicate extreme threat and imminent high-level aggression.
Head position—e.g., the head down, only occasionally pointed at another dog, may be a placatory sign; the head turned to one side may be a calming signal; the head pointed unwaveringly at another dog may signal threat.
Body features, demeanour and gait—e.g., “play bow” when facing another dog, crouched with front legs extended, rear body and tail elevated, may be an invitation to play; rolling on the back and rubbing the shoulders on the ground may show the dog is calm/relaxed; sitting with one forepaw raised may indicate the dog is unsure/anxious; muzzle nudge to threatening dog may represent placation; when approached, sitting and allowing itself to be sniffed, may show the dog is confident and not threatened; rolling on its side or back exposing its belly with no eye contact may represent extreme placation; lowered body, cringing while looking up may indicate fear or uncertainty; stiff-legged, standing upright may signal a challenge; slow stiff-legged movements, body sloped forward, feet braced may indicate a potentially aggressive dog; hackles raised may indicate threat of aggression or, alternatively, fear or uncertainty.
provides examples that are expressive of emotional state and/or intentions, and indicate that tail behaviour, in itself or, importantly, in combination with other behaviours, enhances a dog’s capacity to communicate. Further enhancement is apparently achieved by the laterality of tail wagging, the direction of which may signal positive and negative emotional states. Thus, a dog seeing its owner, a positive stimulus eliciting approach tendencies, exhibits a higher amplitude of tail wagging movements to the right side, whereas a dog seeing a potentially threatening unfamiliar dog, a negative stimulus eliciting withdrawal tendencies, exhibits a higher amplitude of tail wagging movements to the left side [46
]. Importantly, dogs also seem to respond emotionally to others displaying such tail-wagging asymmetry, because when seeing another exhibiting left- rather than right-biased tail wagging the observer dog shows elevated cardiac activity and higher scores for anxiety behaviours [47
2.4. Tail Behaviour Is an Integral Element in Canine Communication
It is argued here on the basis of the above observations that despite it being a single appendage, tail behaviour is so closely integrated into canine communication that docking can represent a major impediment to unambiguous interactions between different dogs and between dogs and people. For example, it has been suggested that docked as opposed to undocked dogs may be subject to more frequent aggressive encounters because of increased chances of social misunderstanding [1
]. This view is supported by an informal study of 431 encounters between dogs with long or short (usually docked) tails, where 12% or 49 encounters involved aggressive interactions [36
]. Of these 49 confrontations, 53% or 24 involved dogs with short tails as opposed to 24% or 12 predicted from proportions in the mixed population. Although not entirely valid, given the informality of the study, it is nevertheless interesting to note that this difference was highly significant (Chi square p
< 0.0001). In any event, it seemed that the dogs in this study with short tails were twice as likely to have aggressive encounters than were dogs with longer (intact) tails [36
]. The following observations are also consistent with this: particular tail positions send placatory signals to other dogs [33
] (Table 1
); some forms of tail wagging may be self-calming [34
]; and in a robotic dog study, a long tail was more effective at conveying intraspecific cues than was a short tail [48
]. Moreover, it is noteworthy that tail activity and position are strongly integrated with other behaviours, and thereby significantly contribute to signalling wide ranges of both negative and positive emotions, moods and intentions which are of daily welfare significance to dogs.
Many of those who oppose bans on docking (e.g., [49
]) and some others commenting on the practice (e.g., [12
]) explicitly or implicitly consider tails to be a dispensable appendage and in doing so clearly disregard tail behaviour as a key communication tool. The detailed analysis presented above, incorporating consideration of the functional foundations, sensory components and key features of body language, including tail behaviours that are integral to canine communication, challenges such views and strongly supports bans on non-therapeutic tail docking.
5. Discussion and Conclusions
It is apparent that the genetically pre-programmed emotional drive exhibited by human beings, and other mammals, to care for and protect vulnerable young of their own and some other species is an important, yet often unrecognised factor that influences decisions about what are acceptable and unacceptable ways of treating newborn and young animals (Section 4.1
). This scientifically validated emotional motivation-to-nurture, objectively observed, should be acknowledged as being of genuine significance in any such deliberations. This is both to affirm its authenticity and to be aware of potential pitfalls that may arise if its influence on interpretation of responses to potentially painful procedures are not considered. Thus, the references above to misinterpretation of puppies’ behavioural responses to tail docking (Section 4.2
) are not intended to be critical of the many observers who believe that puppies experience significant acute pain (e.g., [117
]); rather, they are to highlight the caution it is now understood should be exercised when evaluating those conclusions.
Reinforcing this point is the past faulty extrapolations of information about pain responses in the young of species that are neurologically mature at birth to puppies which are neurologically immature at birth (Section 3
). However, the recent study of electrocortical responses to nociceptive barrages in rat pups [79
] provides more information that is directly applicable to puppies. This study demonstrates convincingly that electrocortical activity typical of a “pain state” is not generated by surgically-induced nociceptive barrages until 14–21 days after birth. These observations in rat pups, when combined with the report on development of electrocortical activity in canine puppies [82
], confirm that both the degrees of neurological immaturity at birth and the subsequent patterns of cerebral maturation are indeed similar in rat pups and canine puppies, and thereby validate extrapolation of this information to puppies. It may be concluded, therefore, that the initial absence of sufficient cortical-subcortical interactivity in puppies within 7 days of birth renders them incapable of consciously experiencing pain when tail docked at that age. It also shows that their behavioural responses, particularly vocalisations [2
], are generated by subcortical processing of the associated nociceptive barrages.
Those who have opposed bans or restrictions on canine tail docking on the basis that it does not cause significant acute pain (e.g., [50
]) may consider themselves to be vindicated by the analysis presented thus far. However, it is the totality of negative impacts that needs to be considered and, as outlined below, the remaining impacts, taken together, still strongly favour banning non-therapeutic tail docking of puppies.
Thus, as outlined above, there is evidence that tail docking within 7 days of birth is likely to cause an ongoing heightened generalised sensitivity to pain (hyperalgesia) and, in the tail stump, neuroma-induced chronic pain and persistently greater sensitivity to touch that elicits pain (Section 3.2
Other negative impacts of tail docking in puppies, discussed in detail elsewhere [1
], also need to be considered. These include long-term loss or impairment of the following tail-related functions in some dogs: counterbalancing actions during complicated movements, as also stabilising the vertebral column and supporting the actions of back muscles; roles in successful and hygienic defecation thereby minimising rectal dilatation, rectal sacculation and faecal incontinence; maintenance of pelvic diaphragm integrity by minimising the risk of perineal hernia; and in females of large breeds, reducing their predisposition to urinary incontinence. Also included are possible acute complications of the procedure itself, such as haemorrhage, necrosis, infection, septicaemia, meningitis and in extreme cases, death [126
]. Although the prevalence of these negative impacts has not been well documented [12
], it is likely to vary with the proficiency of the docker and how quickly veterinary support is sought when adverse outcomes are recognised [6
Importantly, the present detailed analysis shows that loss of the tail likely causes other persistently significant harms. These arise because tail behaviour is such an integral part of canine communication that docking can markedly impede unambiguous interactions between different dogs and between dogs and people (Section 2
). These interactions extend well beyond aggressive encounters, emphasised to date [1
], and include the expression of a much wider range of negative emotions, moods and intentions (Section 2
and Table 1
) that are of daily significance for dog welfare [119
]. In addition, and not previously emphasised, docking can also compromise unambiguous communication of positive emotions, moods and intentions between dogs (Section 2
and Table 1
), which are equally important for their welfare [118
]. Taken together these observations strongly challenge assertions that the tail is a dispensable appendage and provide compelling evidence that supports bans or restrictions on non-therapeutic tail docking of puppies.
The present analysis therefore raises the matter of how such bans or restrictions may best be framed in animal welfare legislation, regulations or professional standards. It is apparent that primary reference to the avoidance of acute pain and distress caused by the procedure itself will be vulnerable to scientific challenge unless the puppies are more than about 3 weeks of age. “Lasting harm”, however, shows more promise as a basis, in particular in light of the significant lifelong impediments to communication in all docked dogs, as well as the likely imposition of chronic pain and/or hyperalgesia in a high proportion of dogs, and the other functional or pathological complications observed in some dogs.
Recognition that animals of welfare interest are sentient is important in this context, as sentience is the ability to perceive by the senses. A capacity for sentience combined with consciousness enables animals to have both negative and positive experiences which are important to them and which influence their welfare. Moreover, animals’ ability to communicate with each other and, in some cases, with other species including human beings, is also an expression of their sentience. It is clear that neurologically mature newborns develop the capacity
for sentience before birth, enabling them to express
it when they become conscious within minutes or hours after birth. In contrast, young that are neurologically immature at birth apparently only develop the capacity
for sentience and then express
it from 2–3 weeks after birth [69
Declarations that animals of welfare interest are sentient are spreading internationally. For example, such declarations have been expressed in the European Union via the Treaty of Lisbon (2008), via laws in France (2015), New Zealand (2015) and Quebec (2015) [129
], by at least 46 countries which supported a proposal that the United Nations issue a Universal Declaration on Animal Welfare [130
], and by the 180-member countries of the World Organisation for Animal Health (OIE) which, in adopting the OIE Global Animal Welfare Strategy 2017, accepted a statement recognising animal sentience [131
]. These developments reflect a major shift in human attitudes towards animals. Hence, legal and other means for recognising sentience among animals, including dogs, are important because they challenge their relegation to the status of commodities whose primary purpose is taken to be the satisfaction of human whims, however trivial.
Reasons that support the non-therapeutic tail docking of dogs have been extensively critiqued (e.g., [1
]. When evaluated using the six questions framed by Morton [1
], and somewhat rephrased by Wansbrough [3
], they fall a long way short of justifying the lasting harm docking causes. The present analysis adds further weight to this view. These six questions bear repeating here [1
Is there adequate evidence that leaving the dogs intact predisposes them to harmful consequences?
Is there compelling evidence that the proposed interference is in the best interests of the dogs and would be beneficial to the dogs?
Would the harmful consequences or the benefits occur in a significant proportion of the dogs and therefore justify conducting the procedure on all dogs of a particular breed?
Does the proposed interference cause greater harm to the dog than the damage it is intended to prevent?
Is there another way with no, or fewer, adverse effects that would achieve the same end?
Does the increase in “value” as a result of the interference justify the harm done to the dog?
Finally, it is concluded that non-therapeutic tail docking of dogs of any age should be banned. It is recommended that justification for such bans included in laws, regulations or professional standards should not be stated in terms the presumed pain and distress caused by the procedure itself at the age when docking is usually performed in canine puppies. Rather, the preferred approach would be simply to state that “non-therapeutic tail docking of dogs is not permitted”. However, if a justification is required legally, the present analysis shows that statements to the effect that “tail docking represents the unnecessary removal of a necessary appendage” would apply to all docked dogs and is supportable by robust scientific observations.