Guinea pigs – introduction

Information about the physical and behavioural characteristics of guinea pigs.

Varietal range differences

The most common varieties of guinea pigs are:

  • English or shorthaired – coarse hair, from 3 to 4 cm long, lies very close to the body.
  • Peruvian or silky longhaired – hair over 12 cm long.
  • Abyssinian – characterized by rough, curly rosettes of hair over the body.

Coat colour can vary over a wide range of black/brown/white arrangements, and some mutant strains can also have tortoiseshell and yellow colourings.

Guinea pigs are usually kept as pets, for showing and used in research in Australia. Traditionally however, guinea pigs were used in countries including South America as a source of meat with some countries still maintaining this production.

Guinea pigs are suitable animals for schools with space restrictions, primary schools and inner city schools that cannot have farm animals.

Schools that wish to keep guinea pigs should select a breed suitable for either showing or pets.

Physical characteristics

Characteristic Details
Size Mature animals have a stout build and are about 15 cm long.
Weight Male: 900-1500g. Female: 700-900g.
Age at adult size Male: 10 weeks. Female: 6–8 weeks.
Weight at birth 60–100g.
Gestation period 59–72 days, an average of 63–68 days.
Number of offspring 1-10.
Litter frequency 3-5 per year.
Range of breeding ages 4 weeks to 20 months. Sows should not be allowed to get too old before breeding for the first time as dystocia may occur.
Description at birth Completely covered with fur, eyes open, full set of teeth, young are up and running within one hour.
Feet Forefeet have four broad toes. Hind feet have three toes.
Tail Nil but there is a tailbone, which is barely visible.
Healthy characteristics:
  • Temperature: 37°-38°C
  • Heart rate: 180-340 beats per minute
  • Respiration rate: 85-90 per minute


Guinea pigs have colour vision, which aids in them spotting predators however they have very poor depth perception. To overcome this poor depth perception guinea pigs have hairs on their muzzles called vibrissae, which they use to measure the width of openings. This adaption allows them to move around at twilight and find their bearings in the dark. In addition to this, wild guinea pigs will create a branched network of tramped down paths so that they can easily find their way around and escape predators. This is the key to guinea pigs’ survival as they are very vulnerable prey animals with very little ability to defend themselves.

Image: Guinea pigs have hairs on their muzzles called vibrissae, which they use to measure the width of openings.


Guinea pigs have very highly developed hearing that is much more sensitive than humans. Their sensitive hearing allows them to identify predators and escape from them. They must be able to take flight rather than fight. Guinea pigs also have a keen sense of smell, which helps them to identify predators.

Image: Guinea pigs have sensitive hearing that allows them to identify predators and escape.

Behavioural characteristics

Being defenceless prey animals, guinea pigs are quite timid and their first response to danger is often to freeze. If danger persists after they have frozen, the guinea pig will try and flee. Guinea pigs will rarely try and fight however if forced to they will chew or bite their opposition. Guinea pigs are not ideal animals for observation as they choose to spend a great deal of their lives hiding, however they do respond readily to frequent, gentle handling.

Guinea pigs are social animals and develop strong bonds with their mates. They thrive in an environment with a large group of other guinea pigs and should be kept in a group of at least two animals. They are most active at twilight when they can move around without being noticed and keep a low profile.

Due to their quiet, docile nature, guinea pigs are popular household pets for children. They very rarely scratch or bite. Guinea pigs however cannot be kept with other animals like hamsters, rats and mice, as they cannot defend themselves against these more aggressive animals.

Like many domesticated animals, guinea pigs have remaining wild instincts and behaviours that must be addressed when keeping them in captivity. Guinea pigs are grazing animals that are accustomed to spending a great proportion of their day nibbling and eating vegetation. Guinea pigs kept in captivity require hard objects including nuts and a variety of vegetation to nibble and chew on constantly so that their teeth do not become overgrown and they do not become bored. A bored animal may chew at the cage or other objects inside the enclosure.

Guinea pigs need to be able to express their natural behaviours, grazing, running, socialising, exploring and resting/hiding, in quiet enclosed areas. Providing a quiet enclosed space for hiding is essential. If a guinea pig cannot retreat to a private area they may become stressed, increasing their risk of illness.

Guinea pigs have very high reproductive rates, giving birth up to 5 times per year with litters of up to 10 young. For this reason care must be taken when keeping males and females together. In addition, guinea pigs exhibit post-partum oestrus and can mate and become pregnant within 12-24 hours after giving birth. To ensure this doesn’t happen, the male must be removed from the cage prior to the female giving birth. Reproduction should only be allowed if there is sufficient care, supervision, facilities and area available to be able to care for both the pregnant sow and the young when they are born.


In general, guinea pigs used in schools for pets or for showing should have been handled from a young age so they become quite comfortable with handling and grooming.

As guinea pigs mature, they like set handling patterns and may become agitated if feed, water or containers are changed. Indications of stress include circling, uttering shrill squawks and hissing sounds or, in extreme cases, freezing for up to 30 minutes.

Guinea pigs often become quite vocal in anticipation of food. Females with young will make a soft clucking noise while the young chatter. Care needs to be taken with a sow with young as guinea pigs will stampede if excited and this could result in them trampling their young.

Although guinea pigs form very strong bonds with their mates and are naturally adapted to living in reasonably large groups for social enrichment, protection and comfort, care must be taken when housing males. Mature males should not be kept together as they establish male dominated hierarchies and subordinate animals may be chewed or barbered. Strange males placed together, particularly with a female or in crowded conditions, will fight.


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