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If you watch a group of dogs playing at a dog park, you will quickly notice how carefully they watch one another. Dogs will look over their shoulders as they run, or they will stop and turn around so they can see what the other dogs are doing. When they do this, they’re reading body postures, gaits, tail and ear positions, facial expressions, and even watching for subtle changes in the position of another dog’s fur, such as whether another dog is showing their hackles. “Hackles” refer to the hairs along a dog’s neck and backbone, and “raised hackles” are called piloerection, an involuntary neural response to arousal mediated by the sympathetic nervous system. Dogs may also gather information by looking in a dog’s eyes, though research in this area is limited. It may be that dilated or constricted pupils communicate something about a dog’s emotional state that other dogs can decipher. In addition to this kaleidoscope of visual signals, dogs are also absorbing olfactory and auditory information, all while on the run, which is quite a remarkable feat.
It’s important for dogs to be able to read one another accurately in order for social interactions to go well. The same is true in the human realm, which is one reason that highly successful people tend to be those with high levels of emotional intelligence and well-honed social skills. One of the reasons dogs can get into sticky situations with one another is when they misread visual or other signals, and some dogs are much better at reading signals than others. Spend any time at a dog park, and you will certainly notice a few dogs who are socially awkward and don’t seem very good at interacting with other dogs. Oftentimes, these dogs have trouble finding play partners. Marc has noted that there often seems to be a relationship between the social skills of a dog, or lack thereof, and those of their human, but that’s another story.
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One of the mysteries of a dog’s world is how they recognize other dogs as belonging to the category “dog.” Obviously, dogs recognize other dogs by smell, but they also seem able to recognize other dogs using only sight. A very interesting study conducted by Dominique Autier-Dérian and her colleagues found that dogs can identify other dogs using facial features alone, in the absence of other cues such as movement, scent, and sound. Dogs were very good at picking out the faces of other dogs, among human and other domestic and wild animal faces. C. Claiborne Ray, discussing this study, remarked, “Ranging in size from a tiny Maltese to a giant St. Bernard, and showing myriad differences in coats, snouts, ears, tails and bone structure, dogs might not always appear to belong to one species. Yet other dogs recognize them easily.”
We often hear dog owners say something like, “My vizsla loves other vizslas more than any other kind of dog, and she also knows they are vizslas.” Can dogs really recognize other dogs of the same breed? Nobody knows, but a lot of anecdotal evidence suggests that they might. If they do, it is likely that the cues lie in the dog’s olfactory sense, and perhaps in the identification of what’s called the major histocompatibility complex, or MHC. The MHC is a set of surface proteins found on the cells of all mammals, and it is involved in immune function. It’s thought to play a role in the selection of mates who are not too closely related genetically. The MHC may present as a kind of olfactory “signature” allowing dogs to determine genetic familiarity, but there hasn’t been any research in this area. Nonetheless, many people believe their dog shows a preference for others of their same breed.
Dogs need to be able to interact with other dogs. This is what dogs are “made” for, if you will. Many of their cognitive skills and the components of their behavioral repertoire have evolved to help them communicate more effectively with others of their own kind. It is sad to think that these amazing capacities could go unused, which is why giving our dogs ample opportunity to interact with other dogs and to practice their communication skills is one of the most important forms of social and cognitive enrichment we can and must provide.
Tales About Tails
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You may wonder why tails are included in a section on sight. Well, among other things, a dog’s tail is an important visual tool for communication. We can gather a lot of information about what a dog is feeling by observing their tail, and of course, tails are critical to dog-dog interactions. Looking at a tail in isolation, however, never tells the whole story; that would be like reading only part of a sentence. To fully understand what a tail is communicating, it needs to be seen in the context of a broader range of composite signals, including ear positions, facial expressions, body postures, vocalizations, odors, and gait. Tails may also be used to disperse odors, such as the scent from a dog’s lovely information-packed anal gland.
Some interesting research has been done into what different tail movements are trying to communicate. As you likely know, a wagging tail can mean different things, depending on the kind of wag and the context. A loose wag is probably friendly, whereas a stiff wag likely signals assertiveness or aggression. However, there are no hard-and-fast rules.
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Research has also shown that tail wagging with a bias to the right indicates that a dog is happy and relaxed, whereas left-bias wagging may indicate anxiety. In one study, dogs seeing their owners were more likely to show high-amplitude wagging with a bias to the right side (showing left-brain activation), while dogs seeing dominant unfamiliar dogs tended to wag to the left (showing right-brain activation). These findings are consistent with the hypothesis that dogs have a left-hemisphere specialization for approach behavior and a right-hemisphere specialization for withdrawal behavior.
More recent research by the same group of scientists found that dogs respond emotionally to the tail-wagging bias of other dogs. The scientists analyzed the behavior and cardiac activity (a rough measure of calmness or anxiety) of a group of dogs watching images of other dogs wagging. Dogs consistently showed more pronounced emotional reactions to and were stressed by left-wagging tails.
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What if a dog loses their tail? Stanley Coren tells a story about a dog whose tail had to be amputated after an unfortunate dog-motorcycle collision. Other dogs seemed unable to understand what she was trying to communicate. Marc’s friend, Marisa Ware, told him the story of her dog, Echo, who lost her tail in an accident. After the loss, Echo changed the way she communicated with dogs and people by using her body and ears to compensate for the loss of her tail. Tailless Echo now relies more heavily on her ears to express her feelings. When she is excited to see someone, she puts her ears very far back and will almost wiggle them. She also has developed a kind of “hop-wiggle,” taking a little hop and wiggling her butt very quickly if she is excited to see someone. Echo never did the “hop-wiggle” before losing her tail.
Even the shortening of a tail, such as through docking, seems to inhibit a dog’s ability to communicate with other dogs. To investigate the role of tail length in dog-dog encounters, a team of researchers built remote-controlled replicas of dogs with different lengths of tail, and they observed more behavioral nuance in the reactions of dogs to long-tailed versus short-tailed replicas. This suggests that more communicative information was gleaned from a long tail, which may mean that a longer tail is more effective at sending messages than a shorter tail.
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The long and short of it is that tails are important to dogs. Thus, tail docking is a freedom inhibitor (and a form of disfigurement) that limits a dog’s ability to communicate. We are in support of enlightened breed standards that don’t involve cutting off puppies’ tails.
Dogs 'Speak' with Their Ears
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Like a tail, a dog’s ears are an important visual signal in dog-dog and dog-human interactions. The next chapter discusses hearing, while this section considers what ears say by their movement and position. Take the time to watch your dog’s ears closely, since they can be a good indicator of how your dog is feeling. Ears are part of the group of composite signals — which include a dog’s face, body, tail, vocalizations, gait, and odors (some of which we are only partially privy to) — that complete the sentence of what a dog is feeling.
For example, if a dog twitches their ears, moving them back and then forward a bit, it may indicate indecision or ambivalence. Pricked ears signal that a dog is paying attention. If Maya pricks her ears, Bella will immediately respond by barking. Bella’s motto is “bark first, then ask why.” By watching the direction another dog is turning an ear, dogs can find out information about where to look. Ear position is important during dog social encounters, including play. For example, flattened ears can signal submission if combined with submissive body posture, and “up” ears can signal excitement and intention to continue play. Flattened ears might also be a way for a dog to avoid getting them nipped.
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We have been asked whether dogs like basset hounds with long, floppy ears have a harder time communicating through ear positions. It’s possible that floppy ears don’t allow for quite as much expressiveness, but we really don’t know.
As with tails, we support breed standards that don’t involve cropping or otherwise changing the natural shape of a dog’s ears. Doberman pinschers, Boston terriers, and Great Danes are a few of the breeds in which ear cropping is still common. During the ear-cropping procedure, the pinnae (earflaps) are altered. The pinna functions to funnel sound into the ear canal, and so dogs with cropped ears lose some acuity in their hearing; they also lose the ability to rotate the ear fully, and this makes it harder for them to communicate with their ears.