Physical characteristics

Members of the dog family range in weight from 3-165 (1.3-75 kg). Coat colors and patterns vary significantly: black, black and white, brown, and red are all very common coat color in many dog breeds. As a family they have longer legs in relation to their weight than the other carnivore families. Their economical trotting gait allows them to cover large areas in search of prey, and most species can accelerate to 25-35 mph (40-56 kph) to run down prey. Top speed can usually be maintained for at least a mile, although prey are seldom pursued for that distance. Three species with shorter legs, the small-eared dog and bush dog of South America and the rac coon dog of eastern Asia live in dense forest. Five claws on the front feet and four on the back is typical. The fifth claw on the foreleg, the dew-claw, is almost vestigial and does not reach the ground. This claw is absent in African wild dogs.

Jaws and teeth are adapted to grab and chew prey. The tooth formula is 3/3, 1/1, 4/4, 2/3 for all species except the bush dog which has lost two molars on the upper and lower jaw, the dhole which has lost one molar on the lower jaw, and the bat-eared fox which has added two molars to the upper jaw and one to the lower jaw. The canines are longest in rodent catching species and shorter and sturdier in species killing larger prey. The last premolar in the lower jaw and the first molar in the upper jaw are modified into blades, or carnas-sials, which can cut flesh. The molars have grinding surfaces for crushing either bone or vegetable food. All the cheek teeth of the bat-eared fox look similar with multiple sharp cusps for penetrating insect exoskeletons, their primary prey.

The gut is simple and usually about five times the length of the animal. It is a bit shorter in highly carnivorous species. Most canids "wolf their food, rapidly swallowing it. When pups are present they can regurgitate food up to 12 hours after eating.

Coyote Physical Adaptations
Coyote (Canis latrans) pups play and practice fighting. (Photo by Erwin and Peggy Bauer. Bruce Coleman, Inc. Reproduced by permission.)
Underground Bat Eared Fox
A bat-eared fox (Otocyon megalotis) listens to the larva in a dung beetle ball underground. (Illustration by Wendy Baker)

It is not clear if this represents an adaptation to slow digestion or just a result of swallowing large bits in the first place.

Canids can certainly smell better than humans; their sight appears to be comparable to that of humans for most species but they have a higher ratio of rods to cones which should produce less color discrimination but an ability to operate at low light levels. Many species forage at night. Hearing is always acute, although the size of the external ears can be misleading as the ears are also used to radiate heat. The Arctic fox (Alopex lagopus) and the raccoon dog have small ears. Body lengths without tail range between 18.3 and 28.7 and (46.5-73 cm) and tail lengths are approximately 9.8-20.5 in (25-52 cm). Bat-eared foxes can hear the sound of termites foraging under ungulate dung and many species locate rodents by their rustle in the grass.

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