General information

Guinea pigs, also called cavies (or cavy for a single guinea pig), originated in South America where the Incas used them as food. They were probably introduced into Europe soon after the first Spanish explorers returned from that continent in the 1500s. They became favorite pets in the early part of this century. Guinea pigs are also bred as show animals with a wide variety of coat colors and fur types. The 3 most popular breeds (there are probably 13 or more different breeds) are: the English or common with short, straight, fine hair; the Abyssinian with rough, coarse hair growing in rosettes or whorls; and the Peruvian with its long, straight, silky hair. There is a wide range of fur colors and patterns as well as hairless or “skinny pigs”.

“The Incas used them as food.”

Males are called boars and females are called sows. Males tend to be larger than females and their weight varies from 700 – 1200 grams.

Guinea pigs live 5-6 years (although some can get to 8 years old). Older male animals have a “grease gland” on the skin at the base of the spine by their hind end. Guinea pigs have 4 toes on the front feet and 3 toes on the back feet.

If a guinea pig senses danger, it will either freeze or make an explosive attempt to run away (if in a group, they will stampede). Guinea pigs do not see well but have well developed senses of smell and hearing. They are communicative and use a wide variety of sounds to express themselves.

“If a guinea pig senses danger, it will either freeze or make an explosive attempt to run away (if in a group, they will stampede).”

They do not tolerate changes in their diet or environment.

Guinea pigs, like humans and primates, require a dietary source of vitamin C.

Guinea pigs are generally hardy, easy to care for and, if handled frequently and gently, make great family pets. They rarely bite or scratch and are docile, non-aggressive, responsive animals.

Housing

Housing your guinea pig is not particularly difficult, with a large variety of hutches and cages available commercially. Guinea pigs should be kept indoors. An indoor cage size of 18″ x 24″ (45 x 60 cm) should comfortably accommodate 1 or 2 guinea pigs. Even though they are not good at jumping or climbing, the cage should be secure and at least 10″ (25 cm) in height. Remember, bigger is better; the biggest cage you can afford is too small!

Cages can be constructed of plastic, metal or wire, as long as they are easy to clean daily. Solid flooring is best as wire mesh floors can cause injury and may be associated with an infection called bumblefoot (ulcerative pododermatitis). Safe bedding includes abundant hardwood shavings (such as aspen), hemp, shredded paper products or pellets, and corncobs. Guinea pigs can quickly make a mess of a cage. Food and water dishes should be large heavy ceramic dishes to prevent spilling, but water is readily accepted from a sipper bottle. A small upside-down box or container is a welcomed shelter. Since they are social animals guinea pigs can be kept in small to medium groups. However, if the sexes are mixed, they will mate and therefore quickly increase the number of animals! To avoid this problem, it is advisable to keep to same sex groups (or neutered and spayed pets). Temperatures between 65-80º F (18º – 26º C) are ideal. Anything over 80 °F (27 °C) will increase the likelihood of heat stroke, especially in animals that are overweight or pregnant.

Breeding

Guinea pigs reach sexual maturity at around 3 – 4 months, but should not be used for breeding for another three months. After about eight months of age, the female guinea pig’s pelvic bones become more tightly fused and if she has not had a litter by that time, producing young can become more of a problem. You might ask why that is a problem since animals of most species can delay giving birth until they are older. The difference is that sows gives birth to 2 – 4 fully developed, relatively large, fully furred offspring with eyes open and the ability to eat solid food (although they will still nurse). The average gestation period is 63 days. These large babies have a hard time getting through the pelvic canal unless the mother’s pelvic bones are relatively immature and malleable or mobile.

These large offspring also predispose the mother to pregnancy toxemia. This is a metabolic disorder resulting in low blood calcium and high blood pressure. It manifests as loss of appetite in the early stages, deteriorating to muscle twitching and coma. Prompt veterinary attention can save animals but the problem can be reduced to a minimum by providing plenty of water and green foods during pregnancy, as throughout life.

“Large offspring also predispose the mother to pregnancy toxemia.”

Guinea pigs, like chinchillas, are one of a group of rodents called the hystricomorphs; these rodents have an unusual reproductive physiology and breeding strategy. Hystricomorph rodents begin pregnancy with a much larger number of fetuses in the uterus; many of the fetuses die before birth, some at a very early stage, and others late in gestation or even at birth. The reason is unclear but it may be a mechanism for producing the maximum number of offspring for a limited and varying food supply. Guinea pigs have a relatively high incidence of dead babies, and if the gestation should continue over 70 days, it is likely that the entire litter will be stillborn.

As with many rodents, the female guinea pig will be able to mate within a few hours of giving birth, but should not be allowed to; it is much better if she has time to recover and replenish her metabolic reserves before becoming pregnant again. If your guinea pig has a large litter (over three or four piglets), it is worth fostering some off on another sow (female), since guinea pigs have only two nipples to suckle their offspring.