Mouse

The domestic mouse is descended from the wild house mouse, which originated in India and spread globally as a commensal species alongside human expansion. Mice were kept in captivity in China and Japan as early as the 12th century CE, where selective breeding for unusual coat colours and patterns began — the precursor to today's 'fancy mouse' hobby. Laboratory use of mice beginning in the 19th and early 20th centuries further refined domestication, and domestic mice as companion animals have been popular ever since.

Mice are small, quick, inquisitive and endlessly entertaining. They are most active at night and in the early morning, which makes them particularly engaging pets for owners who are home in the evening. They are social animals and females in particular are best kept in pairs or small groups; males can be kept together if introduced as young litter-mates, but two unrelated adult males will usually fight.

Mice are one of the most accessible and affordable small pets available, making them an excellent first pet for children with appropriate supervision, or for adults who enjoy observational animal keeping.

Mice are active, agile and territorial, and their enclosure should reflect this. A minimum enclosure size for two to three females is 60cm W x 30cm D x 40cm H; larger is always better, as mice use every centimetre of their space. Wire cages with small bar spacing (no more than 0.7cm) allow good ventilation but must have a solid, tray-based floor — wire floors are harmful to mouse feet. Alternatively, glass or acrylic tanks with a well-ventilated wire mesh lid provide good visibility and prevent escape.

Mice are burrow-happy animals and require a deep layer of bedding — at minimum 10–15cm of substrate — to allow natural burrowing behaviour. Suitable bedding materials include recycled paper pulp bedding (recycled paper pulp bedding), kiln-dried aspen shavings, or a mixture of both. Avoid pine and cedar shavings, which contain aromatic oils harmful to mouse respiratory health. Hay can be added to the bedding layer for nesting material.

Essential cage fittings include at minimum one solid-surface running wheel (a silent spinner of appropriate size — 15–17 cm minimum diameter to prevent spinal damage), one or two small hides or igloos, a sipper water bottle, a small ceramic or glass food bowl, and a variety of toys and climbing structures. Nest building material such as torn paper strips or hay should always be available. The cage should be spot-cleaned every two to three days and fully cleaned once a week.

Mice are omnivores and require a varied, nutritionally complete diet. The dietary foundation should be a quality mouse or rat pellet that provides complete nutrition and prevents the selective feeding that occurs with seed-mix-only diets. Pellets should constitute approximately 50–60% of the total diet and be available at all times or offered in a measured daily portion.

Supplement daily with small pieces of fresh vegetables — broccoli, capsicum, corn, carrot, peas, leafy greens and cucumber are all suitable. A small piece of fruit such as apple (no seeds), blueberry or banana can be offered sparingly as an occasional treat. Protein can be offered 2–3 times per week in the form of a small piece of cooked chicken, a tiny portion of boiled egg, or a small dog biscuit.

A small mixed seed and grain treat mix can be scattered in the cage for foraging enrichment, but should not replace the pellet base. Never feed chocolate, caffeine, raw dried beans, sticky foods, very salty or processed human food, or raw potato. Fresh water must be available at all times via a sipper bottle mounted on the cage — bowls are quickly contaminated with bedding and food in a mouse enclosure.

Mice have bright, active personalities and, when well-socialised, will readily run onto a hand, investigate unfamiliar objects with evident curiosity, and engage with a wide range of enrichment activities. Females are generally calmer and more tolerant of handling than males. Mice are primarily observational pets — their speed and size mean they are enjoyed as much through watching as through direct contact, and they provide near-constant activity and interest during their active periods.

The best way to pick up a mouse is to scoop it up gently in a cupped hand — place the flat hand in the enclosure and allow the mouse to walk on of its own accord, then lift slowly and smoothly. If a mouse is jumpy or nervous, it can be picked up quickly and briefly by the base of the tail (close to the body), transferred immediately onto a flat surface or the opposite hand, then handled normally. Never leave a mouse dangling by its tail, as this causes injury and significant distress.

Handle mice regularly to maintain tameness. Short, calm sessions of five to ten minutes are more effective than infrequent long ones. Always handle close to a surface — mice are very fast and a fall from height can be fatal. Children should always be supervised and taught to handle mice in a seated position, close to the floor or a table surface.

Mice are remarkably active and curious and benefit greatly from environmental variety. A solid-surface running wheel is one of the most important enrichment items — mice may run several kilometres per night on a wheel and it is essential for physical and psychological health. Always use a solid-surface, appropriately sized wheel; mesh or spoke wheels can trap and injure feet and tails.

Provide a rotation of climbing structures (ladders, ropes, hanging tubes), cardboard tunnels and boxes, and small foraging items (scatter a pinch of seed mix through the bedding, hide treats in paper bags or folded cardboard) to encourage searching behaviour. Nest-building is an important natural behaviour — always have paper strips, hay or tissue squares available for the mice to collect and arrange. Introducing novel safe objects — a small empty container, a new hide shape, a foraging ball — during cage cleans maintains environmental novelty. Female mice in groups engage in social play and mutual grooming that is itself a meaningful form of natural enrichment.

Respiratory infections: Mice are susceptible to bacterial and viral upper respiratory infections, often presenting as laboured breathing, clicking or wheezing sounds, sneezing and reduced activity. Damp bedding, poor ventilation and overcrowding increase risk. Seek veterinary attention for any mouse showing respiratory symptoms.

Mites and lice: External parasites cause excessive scratching, hair loss and skin irritation. Treat with a veterinary-recommended small animal parasite treatment and replace all bedding.

Tumours: Mice are prone to developing tumours, particularly mammary tumours in females. Regular handling allows early detection.

Wet tail (Proliferative ileitis): A bacterial intestinal disease causing severe diarrhoea, lethargy and dehydration — more common under stress or in animals recently moved; seek veterinary attention promptly.

Barbering: A stress or boredom behaviour where dominant individuals chew the whiskers and fur of cage-mates; increase cage size, enrichment and review group dynamics if observed.