Dog - Attributes
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Modern dog breeds show more variation in size, appearance, and behavior than any other domestic animal. Within the range of extremes, dogs generally share attributes with their wild ancestors, the wolves. Dogs are predators and scavengers, possessing sharp teeth and strong jaws for attacking, holding, and tearing their food.
Dogs are predators suited to chasing after, leaping at, and killing prey. (pictured: Weimaraner)
Their legs are designed to propel them forward rapidly, leaping as necessary, to chase and overcome prey. Consequently, they have small, tight feet, walking on their front toes; their rear legs are fairly rigid and sturdy; the front legs are loose and flexible, with only muscle attaching them to the torso.
Dogs are dichromats and thus, by human standards, color blind. Because the lenses of dogs' eyes are flatter than humans', they cannot see as much detail; on the other hand, their eyes are more sensitive to light and motion than humans' eyes. Some breeds, particularly the best sighthounds, have a field of vision up to 270° (compared to 100° to 120° for humans), although broad-headed breeds with their eyes set forward have a much narrower field of vision, as low as 180°.
Dogs detect sounds as low as the 20 to 70 Hz frequency range (compared to 16 to 20 Hz for humans) and as high as 70,000 to 100,000 Hz (compared to 20,000 Hz for humans)2, and in addition have a degree of ear mobility that helps them to rapidly pinpoint the exact location of a sound. They can identify a sound's location much faster than can a human, and they can hear sounds up to four times the distance that humans can.
Dogs have nearly 220 million smell-sensitive cells over an area about the size of a pocket handkerchief (compared to 5 million over an area the size of a postage stamp for humans). Some breeds have been selectively bred for excellence in detecting scents, even compared to their canine brethren. Other than the oversimplified obvious, i.e. chemical compounds that affect chemical sensors in the nose, what a dog actually detects when he is scenting is not really understood; although once a matter of debate, it now seems to be well established that dogs can distinguish two different types of scents when trailing, an air scent from some person or thing that has recently passed by, as well as a ground scent that remains detectable for a much longer period.
The characteristics and behavior of these two types of scent trail would seem, after some thought, to be quite different, the air scent being intermittent but perhaps less obscured by competing scents, whereas the ground scent would be relatively permanent with respect to careful and repetitive search by the dog, but would seem to be much more contaminated with other scents. In any event, it is established by those who train tracking dogs that it is impossible to teach the dog how to track any better than it does naturally; the object instead is to motivate it properly, and teach it to maintain focus on a single track and ignore any others that might otherwise seem of greater interest to an untrained dog. An intensive search for a scent, for instance searching a ship for contraband, can actually be very fatiguing for a dog, and it must be motivated to continue this hard work for a long period of time.
All dogs have a tremendous capacity to learn complex social behavior and to interpret varied body language and sounds, and, like many predators, can react to and learn from novel situations. The requirements of coordinating complex social behavior requires that canines have the ability to sense and deliver a wide variety of cues via body language, more so than for even humans, who can use language for the same purpose.
Physiologically, this correlates with such features as a large number of nerves innervating the facial muscles of dogs, allowing subtle control of a wide variety of facial expressions; in contrast to cats, for instance, who have many fewer nerves governing their facial muscles, resulting in a smaller repertoire or "vocabulary" of expressions. This ability to read and deliver nonverbal cues makes dogs expert at reading human beings, as well, often even more so than other humans are, who rely on language. Most dog owners have a large collection of stories about their dogs recognizing individuals by their footsteps outside the door, and so on.
Dog coats, colors, and markings
Dogs exhibit a diverse array of coat textures, colors, and markings, and a specialized vocabulary has evolved to describe them.
Coat colors range from pure white to solid black and many other variations.
Originally, dogs all had dense fur with an undercoat and long muzzles and heads, although both of these features have been altered in some of the more extremely modified breeds, such as the Mexican Hairless and the English Bulldog.
One often refers to a specific dog first by coat color rather than by breed; for example, "a blue merle Aussie" or "a chocolate Lab". Coat colors include:
Black: Usually pure black but sometimes grizzled.
Brown: From mahogany through very dark brown.
Red: Reminiscent of reddish woods such as cherry or mahogany; also tawny, chestnut, orange, rusty, liver, and red-gold.
Yellow: From pale cream to a deep yellowish-gold tan.
Gold: From pale apricot to rich reddish-yellow.
Gray: Pale to dark gray, including silver; can be mixed with other colors or various shades to create sandy pepper, pepper, grizzle, blue-black gray, or silver-fawn.
Blue: A dark metallic gray, often as a blue merle or speckled (with black).
Sable: Black-tipped hairs; the background color can be gold, silver, gray, or tan.
White: Distinct from albino dogs.
The Dalmatian's coat is one of the more widely recognized markings.
Two-color coats, such as Black and tan, red and white: Coat has both colors but in clearly defined and separated areas; usually the top and sides are darker and lower legs and underside are the lighter color.
Tricolor: Consisting of three colors; usually black, tan, and white or liver, tan, and white.
Brindle: A mixture of black with brown, tan, or gold; usually in a "tiger stripe" pattern.
Harlequin: "Torn" patches of black on white.
Merle: Marbled coat with darker patches and spots of the specified color.
Particolor: Two-colored coat with the colors appearing in patches in roughly equal quantities.
Coat textures vary tremendously, so that some coats make the dogs more cuddly and others make them impervious to cold water. Densely furred breeds such as most sled dogs and Spitz types can have up to 600 hairs per inch, while fine-haired breeds such as the Yorkshire Terrier can have as few as 100, and the "hairless" breeds such as the Mexican Hairless have none on parts of their bodies. The texture of the coat often depends on the distribution and the length of the two parts of a dog's coat, its thick, warm undercoat (or down) and its, rougher somewhat weather-resistant outer coat (topcoat), also referred to as guard hairs. Breeds with soft coats often have more or longer undercoat hairs than guard hairs; rough-textured coats often have more or longer guard hairs. Textures include:
The German Wirehaired Pointer's coat demonstrates a rough texture.
Double-coated: Having a thick, warm, short undercoat (or down) that is usually dense enough to resist penetration by water and a stronger, rougher weather-resistant outer coat (topcoat), also referred to as guard hairs. Most other coat types are also double coated.
Single-coated: Lacking an undercoat.
Smooth-coated: "Smooth" to the eye and touch.
Wire-haired: Also called broken-coated. The harsh outer guard hairs are prominent, providing excellent weather protection for hunting dogs such as the Border Terrier or Wirehaired Pointing Griffon.
Long-haired: Hair longer than an inch or so.
Short-haired: Hair around an inch or so long.
Corded coat: for example, see Puli
Dogs ears come in a variety of sizes, shapes, lengths, position on the head, and amount and type of droop. Every variation has a term, including:
The Basset Hound's ears are extremely long drop ears.
Bat ear: Erect, broad next to the head and rounded at the tip.
Button ear: A smaller ear where the tip folds forward nearly to the skull, forming a V, such as the Jack Russell Terrier.
Cropped ear: Shaped by cutting; see docking.
Drop ear: An ear that folds and droops close to the head, such as most scent hounds'. Also called a pendant ear.
Natural: Like a wolf's.
Prick ear: Erect and pointed; also called pricked or erect.
Rose ear: A very small drop ear that folds back; typical of many sight hounds and the English Bulldog.
Semiprick ear: A prick ear where the tip just begins to fold forward, such as with the Rough Collie.
As with ears, tails come in a tremendous variety of shapes, lengths, amount of fur, and tailset (positions). Among them:
The Basenji's tail is tightly curled.
Corkscrew: Short and twisted, such as a Pug
Docked: Shortened by surgery or other method, usually two or three days after birth; see docking
Odd: Twisted, but not short. Uncommon. Tibetan Terriers have odd tails.
Saber: Carried in a slight curve like that of a saber
Sickle: Carried out and up in a semicircle like a sickle
Squirrel: Carried high and towards the head, often with the tip curving even further towards the head.
Wheel: Carried up and over the back in a broad curve, resembling a wheel.