Mice & Rats

Rats and mice can make great pets, and rats in particular are extremely sociable and intelligent animals.  Their intelligence is exemplified in a study by Dr Silverman in 1978 where rats in individual cages were exposed to tobacco smoke delivered by a tube in each cage.  The smoke was diluted 1 to 100 to clean air.  There is no evidence the rats were familiar with the hazards of smoking to their health, but they hated the smoke.  By the third day the rats had inedpendently taken their own faeces and plugged the tube outlet, patting the home made “cement” with their frot paws to ensure success.

Rats are generally fairly low maintenance on a health front, and very rewarding as pets. However it is important that owners understand their particular dietary and husbandry requirements, as with any pet there are some things to be aware of.



Rats and mice are omnivores which means they eat food of both plant and animal origin, in the wild they are scavengers eating whatever they can find, including seeds, plants, insects and carrion.  A good quality pellet formulated specifically for mice or rats will provide a convenient and nutritionally balanced diet, however it important not to feed to much of this as this will quckly lead to obesity – which is thought to be linked to cancer development and a shorter lifespan.  Supplement your pets diet with vegetables and small amounts of fruit.

Rodents will also often eat some of their own faeces.  This sounds disgusting, but is actually a clever way to obtain nutrients produced by bacteria in the lower intestinal tract that would otherwise be lost in the faeces.  Rats will also eat faeces of other rats in the same colony which helps to promote a distinctive smell that allows differentiation between colony and non colony members.



Your rat or mouse should always have a supply of fresh water available.  This can be provided with a sipper bottle or in a water bowl.  Ensure the water bowl isn’t easy to knock over and make sure the water is changed daily



Cages can be made out of a variety of materials, but it is important that they are well ventilated (so aquariums are not really suitable) easy to clean and not made of any material that can be destroyed by chewing or digging.  The cage floor should be solid but easy to clean.  Bedding should not produce dust (rodents have very sensitive respiratory systems), should keep animals clean and dry and should frequently be changed.
Mental stimulation is also important for rodents, consider toys, hollow balls, tunnels and running wheels and ideally rotate the toys every few days or weeks to stimulate your pets curiosity!  Food treats (though obviously in small quantities) are another good source of environmental enrichment.  Mice and rats should also be provided with the option to retreat from light into a dark burrow when desired

Rats and mice can be kept together or alone, though it is important not to house different species together to prevent transmission of diseases.  Generally rats of the same sex can be kept together, especially if they are raised together, however male rats in particularly may fight.  Male mice will generally fight when housed together unless they are litter mates raised together without females present.  If male and female mice are housed together, breeding will invariably occur.  Female mice can reproduce from 6 to 8 weeks of age and female rats from 10 weeks of age, and rodents can have a new litter every 3-5 weeks!  Neutering rats is possible, it is easier to neuter males than females.


Some Interesting Biological Facts about Rats

– Rats are poor regulators of body heat.  They adapt better to cold temperatures than to heat.  They don’t have any sweat glands on haired surfaces (sweating occurs only on the hairless foot pads) and can’t pant.  For this reason rats should be kept only at temperatures of up to 30 degrees celcius (and ideally at 21-25 degrees celcius).  In hot temperatures rats do not usually increase their water consumption, rather they seek shade or burrow.

– Rats nares (nose openings) can close under water

– When stressed (due to disease / high temperatures / other stressors) rats may develop “red tears.”  This red occular discharge is not actually tears at all but a porphyrin discharge from the Harderian glands, which may also be seen staining the nose and front paws

– Rats cannot vomit (due to the anatomy of their stomachs)

– Vitamin A deficiency can make rats vicious

– Rats are nocturnal and sleep during the day


Some Interesting Biological Facts about Mice

– Mice are poor regulators of body heat due to their large surface area per gram of body weight.  They can tolerate cold better than yeat to a point, but ideally like to be at around 21-25 degrees celcius, and should not be kept at teperatures over 32 degrees celcius.  Mice do not increase their water consumption in hot temperatures, rather they will seek shade or burrow.

– A mouse at rest uses about 3.5mL of oxygen per gram of bodyweight per hour – which is about 22 times more than that used by an elphant (per gram of bodyweight).

– Female mice can have an oestrous cycle (heat) every 4-5 days, and within 1 day of giving birght.  Pregnancy lasts 19-21 days.  Baby mice (pups) are born hairless and with closed eyes and ears, are weaned within 3 weeks, and are able to breed on average when they are about 50 days old though this can vary.

– “Barbering” (using the teeth to pluck hairs from the face of another mouce while grooming) is a dominance behaviour.


For further in depth information on rat and mouse housing and husbandary the veterinary partner rodent care site is an excellent resource.