Rats – introduction

Information about the physical and behavioural characteristics of rats.

Varietal range differences

  • Albino
  • Hooded.

Mutations and hybridizations have led to rats in a multitude of coat colours and pattern combinations.

Rats are commonly used in laboratories for research and scientific work. In schools they are only kept as pets and for showing. They are suitable animals for schools with space restrictions, primary schools and inner city schools that cannot have farm animals.

Schools that wish to keep rats should select individual animals suitable for either showing or pets.

Physical characteristics

Characteristic Details
Size Approximate length from snout to base of tail is 17-21cm. Approximate length of tail is 20–23cm. Overall length is 37–44cm.
Weight Adult male approximately 200-400g. Adult female approximately 250-300g.
Age at adult size 12-14 weeks
Average life span 3 years
Weight at birth 5-6g
Gestation period 20-23 days
Number of offspring 9-11
Range of breeding ages Range of breeding ages: 3–15 months recommended.
Healthy characteristics
  • Temperature: 37°–38°C
  • Heart rate: 300 beats per minute
  • Respiration rate: 100 per minute (can be up to 230 per minute)


A rat’s vision is its least sensitive sense. Its hearing and smell are far superior. Rats can only see in limited colours, mainly blue, green and red. Rats have quite poor depth perception and blurry vision, especially when over a few feet away.

The rat’s sense of touch makes up for its limited vision. The rat’s whiskers, which flick back and forth rapidly, sense its immediate surroundings, brushing against objects and giving the rat a detailed picture of its surroundings.


Rats have very sensitive hearing, allowing them to identify approaching predators or danger and flee quickly or find a hiding place. A rat’s hearing is far superior to a human’s, compensating for its poor sight.

Rats also have a very sensitive sense of smell, allowing them to identify predators, as well as locating their food.

Behavioural characteristics

When healthy, rats are active and inquisitive animals. They enjoy running, jumping, climbing and standing on their hind legs while in their cage. Rats are friendly animals and once accustomed to handling, enjoy being held, groomed, stroked and played with by handlers. They are not aggressive animals and will rarely bite unless provoked. If rats do bite, they will only bite once, not repeatedly. Male rats are more likely to become aggressive than female rats and be more inclined to bite. During the breeding period, it is normal for the male rat to nibble the female’s head or body and to examine her rear end prior to copulation.

Rats are very sociable animals and should never be kept as solitary animals. They are naturally adapted to living in groups for social enrichment, protection, warmth and comfort. Male rats can be housed together as they are not as territorial as mice.

If breeding is not intended, rats should be kept in single sex groups to avoid unwanted pregnancies. They are renowned for their high reproduction rates and this should always be considered when keeping rats in schools. They can have multiple litters each year and each litter can be up to 11 offspring. Female rats will also come into oestrus, and mate, within 24 hours of giving birth so should not be kept in the same cage as a male.

While rats are active animals, they are generally friendly, docile animals that make good indoor pets and appropriate classroom animals for primary schools and inner city schools with limited space. Unlike other small animals like rabbits and guinea pigs, which typically find human interaction quite daunting and stressful, rats enjoy affection and playing once they are familiar with their handler.

Rats are naturally nocturnal animals, making them far more active at night. Normal daytime behaviour involves huddling together to conserve body heat and gain comfort from one another. Healthy rats will always sleep curled into a foetal position. They can become acclimatised to human contact and the school environment and adapt to life as a pet, with increased stimulation occurring during the day.

Cannibalism is rare but does occur and is usually indicative of inadequate diet, maintenance or stress factors.


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