THINGS YOU SHOULD KNOW ABOUT KEEPING GUINEA PIGS
Guinea pigs originated in South America but were probably introduced into
Europe soon after the first Spanish explorers returned from that continent in
the 1500s. Even though they came from a tropical area these rodents proved to
be hardy and adapted to temperate climates such as that of Britain. They became
favorite pets in the early part of this century and are also bred as show animals
with a wide variety of coat colors and fur types.
This is not particularly difficult and a large variety of hutches and cages
have been used. Guinea pigs can be kept outside in the summer and a good draught-free
but well ventilated mobile run on the grass is very acceptable as long as there
is also a dry covered area. Pens should be at least 30cm high to avoid escapes
and should be covered with mesh to keep cats out. Indoor cages in the winter
should allow at least 0.2 square meters of floor space per guinea pig. Since
they are social animals guinea pigs can be kept in small to medium groups, but
clearly mating will increase the number of animals so single sex groups are
advisable. Temperatures between 12 and 20°C are ideal. Anything over 27°C will
lead to heatstroke, especially in animals that are overweight or pregnant.
Guinea pigs are one of a group of rodents called the hystricomorphs with an
unusual reproductive physiology and breeding strategy.
Guinea pigs mature at around 3 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 be 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 with the guinea pig is that she gives birth not to
a large litter of tiny immature young (as the rat or mouse does), but to between
two and four fully developed well furred offspring. 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. These
large offspring 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.
There is a relatively high incidence of dead babies and if the gestation should
continue over 70 days, it is likely that the litter will be born dead. Interestingly
the guinea pig, along with other hystricomorph rodents, starts off with a much
larger set of fetuses in her uterus but many of them die before birth, many
very early on but some late in gestation or even at birth. The reason is unclear
but it may be a mechanism of producing the maximum number of babies for a limited
and varying food supply.
As with many rodents the female guinea pig will be able to mate within a few
hours of giving birth. She should not be allowed to, however, since it is much
better that she has time to replenish her metabolic reserves before becoming
pregnant again. If your guinea pig has a large litter of over three or four
piglets it is worth fostering some off on another sow, since guinea pigs have
only two nipples to suckle their offspring.
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