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Description and Physical Characteristics of Guinea Pigs

By Katherine E. Quesenberry, DVM, MPH, DABVP (Avian),
Kenneth R. Boschert, DVM, DACLAM, Associate Director, Division of Comparative Medicine, Washington University

Guinea pigs, like other cavies, are stout and short-legged. They range from approximately 8 to 19 inches (20 to 50 centimeters) in length for a full grown adult. Adult guinea pigs are about 5 inches (13 centimeters) tall. The average adult weight is 30 to 35 ounces (850 to 1,000 grams). Their normal body temperature is 102 to 104°F (39 to 40°C). The life span of a guinea pig varies, but on average, they live 5 to 6 years (see Table: Guinea Pigs at a Glance).

Guinea Pigs at a Glance


5 to 6 years


30 to 35 ounces (0.8 to 1 kilogram)


8 to 19 inches (20 to 50 centimeters)

Normal body temperature

102 to 104°F (39 to 40°C)

Heart rate

250 beats per minute

Estrus cycle

15 to 17 days

Duration of pregnancy

59 to 73 days

Litter size

1 to 7 (usually 3)

Weaning age

4 weeks

Environmental requirements

65 to 75°F

There are currently at least 13 recognized breeds of guinea pigs. Some of the more common breeds include the American, which has short, smooth hair; the Abyssinian, with short hair that grows in whorls; and the Peruvian, which has longer, silky hair. Hairless breeds have also been developed. Guinea pigs come in several colors and color combinations, including black, tan, cream, brown, and white.

Guinea pig eyes are located on the sides of the head, allowing them to see both forward and backward, though they may have trouble seeing directly ahead. Their heads are blunt and have small ears. Guinea pigs have 4 digits (toes) on their front feet and 3 on each hind foot. Each toe has a very sharp claw. Their hind legs are longer than their front legs. They have no external tail.

Guinea pigs have 20 teeth including upper and lower long incisors (for cutting and tearing), premolars, and molars. A guinea pig’s teeth are “open rooted” and grow continuously throughout its life. They wear down their teeth by eating, chewing, and grinding food. Thus, it is important that your guinea pig’s diet contain a sufficient amount of hays, grasses, and abrasive foods to maintain healthy teeth at the proper length. Fat pads, which are normal, on either side of the mouth can make examination of guinea pig teeth difficult.

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