Rats and Mice

Rats and mice can be very suitable pets for both adults and children.

Rats in particular make excellent pets as they rarely bite, especially if well socialized from an early age. They also display more individual personality than mice and can also be trained.

Rats tend to be more nocturnal than mice and spend most of their days asleep, hence their suitability as pets to people who are out all days.

Mice tend to be more active and move faster, and can leap out of a small child’s hands. They cannot be trained to the same extent as rats.

Male rats tend to be more docile than female rats, but tend to have a stronger smell. Neutering may reduce the smell to a certain extent.

A high percentage of female rats tend to develop mammary tumours in later life (up to 50% in laboratory strains).

A rat or mouse will benefit from being housed with a companion of the same species, and demonstrate a wider range of behaviours when group housed. A pair of rats or mice from the same litter will usually together for their lifespan without fighting. Introducing adult males to each other is not to be recommended; it is easier to introduce older females of both species.

	Rats	Mice
Life Expectancy	2.5-3.5 years	1.5-2.5 years
Water Intake(average daily)	10ml/100g	15ml/100g
Sexual Maturity	6-8 weeks	6-7 weeks
Oestrus cycle	4-5 days	4-5 days
Duration of oestrus	14 hours	14 hours
Gestation	22 days	19-21 days
Litter size (average)	6-16 (10)	6-12 (8)
Eyes open	12-14 days	12-14 days
Weaning age (earliest)	21 days	21 days

Housing

Rats and mice like to gnaw (The incisor teeth have a characteristic chisel shape to them, and have often a yellowish colour caused by the presence of iron pigments. The incisors are also open rooted; this means they will continue to grow continuously).

A cage made of wire with a solid plastic bottom, or an aquarium with a mesh roof, is recommended. The former is preferable as it is better ventilated.

Ventilation and cleanliness are particularly important with respect to the build up of ammonia (which is a potent respiratory irritant and a factor in lung infections involving Mycoplasma pulmonis).

Cages should supply sufficient space for the occupants to exercise and to allow environmental enrichment.

: A shelter to provide the animals with a bolt hole – e.g. a plastic house for mice and a drain pipe for rats

: Floor should be covered with an absorbent substrate (e.g. sawdust, wood shavings)

: Nesting material (e.g. shredded newspaper) should be provided

: Some of the diet can be scattered in the sawdust to allow foraging

: Other provisions for environmental enrichment should be provided including cardboard tubes, sheets of paper to tear up, drain pipes suspended from the cage lid, exercising wheel, cat treat balls and ladders.

Diet

Rodents are omnivorous or herbivorous. To avoid imbalances, feed primarily on commercial rodent diet, which can be supplemented with a wide variety of fresh food, fruit and vegetables – in moderation. Commercial treats should be reserved for special occasions e.g. as training rewards.

Food bowls should be heavy enough to prevent them being tipped over. A water bottle is probably better than a bowl (less cage contamination).

Breeding

Rats and mice are polyoestrous, with no specific breeding seasons.

To breeders, male rats and mice are known as bucks, females as does and the young as kittens or pups.

To best control population numbers, a female should be introduced to a male in the male’s territory for a short time.

Birth often occurs between midnight and 4a.m., and it can be delayed if the mother is lactating. It is best not to disturb the mother and pups for 2-3 days after birth, as excessive handling may cause the mother to eat her young – a particular risk with rats.

A female rat may bite those who disturb her and her young. If the need to examine the pups arises, move the mother to a separate cage, and use latex gloves on handling the pups to prevent the handlers scent covering the young.