JSPCA RAT AND MOUSE FACT SHEET

History and Biology

The common pet rat (Rattus norvegicus) and mouse (Mus Musculus) are rodents of the Family Muridae.  These species of rat and mouse are the mostly likely to be kept as pets, and in many countries they are bred to show standards and exhibited.

Domestic rats are clean, intelligent and agile and enjoy human company.  They can make wonderful pets.  There are many different varieties of rats with varying markings and coat types.  The most common colours include black, mink, champagne and albino.  The “hooded” pattern is quite common, that is the coat is white and the face and head are coloured.  There are three different coat types that can be combined with any pattern or colour – smooth haired, rex (which has curly hair and whiskers) and hairless rat.  The well known rats, the black and brown rats, are thought to have originated from Asia.   The famous spread of the Black Death (or Bubonic Plague) in the 1300s earned the rat its unsavoury reputation.  However, the rats were merely the hosts of fleas that actually spread the disease.  Rats are very social animals and get lonely if kept alone, so are best kept as a pair or group of the same sex to avoid unwanted babies.  Two boys and two girls will live happily together, if they are littermates.  The average lifespan is about two and a half years.

The domestic mouse bred in captivity makes a friendly pet and comes in a wide variety of colours.  They live, on average, between one to two years and are fully grown at about three months old. Never attempt to keep wild mice as pets.  Mice are happiest with the company of their own kind and, to avoid unwanted babies, it is best to keep pairs, or groups of the same sex.  Males tend to be more aggressive towards each other than females and have a stronger smell, as their urine contains a musk-like substance for marking territory.  

Housing

Rats and mice like to gnaw, so 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 and although a wire mesh lid will help increase aquarium ventilation, it will still be less than in a more traditional wire cage.  Wooden cages should not be used, as the animals will chew their way out.  Ventilation and cage cleanliness are particularly important with respect to the build up of ammonia from urine.  Ammonia is a strong respiratory irritant.  Limiting ammonia build up will therefore help to prevent respiratory disease.  Hence, cages should be cleaned out on a regular basis, at least once weekly, which will also help reduce odours.  Frequency of cage cleaning will vary with the size of the cage and the number of animals in it.  

Cages should supply sufficient space for the occupants to exercise and provide environmental enrichment, such as empty cardboard boxes, sheets of paper to tear up, exercise wheels (with a solid back and floor to prevent injury to the feet and long tails getting caught in the side supports as the wheel turns) and ladders.  If exercise wheels are provide for rats, they must be big enough so that the rat does not have to bend his back whilst inside.   Cages should include a shelter and a place to sleep, such as a plastic house from a pet shop for mice, or a piece of drainpipe for a rat.  Nesting material should be provided, but do not use cotton, nylon or fibre bedding as this could be a danger to your rat or mouse if swallowed.  Alternatively, a nest box can be made from a cardboard box with shredded paper bedding inside.  The cage floor should be covered with a litter material to absorb ammonia from droppings, such as good quality dust free shavings or sawdust.

The best home for your rat is a wire cage, the larger and taller the better as rats are active and love to hide and climb.  Multi-level cages are a good idea.  The rat’s natural instinct is to explore and socialise, so platforms made from piles of logs (natural wood, such as willow, hazel and apple) are great for them to explore or nest under.  Rats may also chew the wood, which will help keep their teeth in trim. 

The best home for your pet mice is a wire cage with a plastic tray floor or a glass or plastic tank with a wire lid.  Mice like to climb, which wire cages allow, but they can squeeze through tiny gaps,  so the spaces between the bars should not be greater than the width of your little finger.  Mice enjoy climbing, so provide branches from fruit trees or even suspend lengths of rope in the cage.  Providing tunnels, such as cardboard or plastic tubes, also allows them to express their natural behaviour.

Rats and mice should be kept inside, away from direct sunlight and draughts and out of the reach of any other pets.  The temperature in the room should be constant.  Their hearing is extremely sensitive so they should be situated away from loud noises such as a stereo.

Diet

To avoid dietary imbalances, it is best to feed rats and mice primarily on a commercial rodent diet, which can be supplemented with a variety of fresh food, fruit and vegetables, but in moderation as too much can result in dietary imbalances, obesity or tummy upsets. ‘Treats’ such as chocolate and yoghurt drops, or sticks consisting of dried grains, fruit and vegetables held together with molasses or honey are sold by pet shops and are readily eaten.  However, they should be reserved for special occasions, as overfeeding of these foods can easily result in obesity and dental problems.  Check where your rat or mouse hoards food and remove any old stale food from those areas.  Rats and mice need feeding daily.   A good quality heavy earthenware food bowl is essential to keep the food dry and clean, and prevent it from being tipping onto the floor of the cage.  The bowls must be cleaned after every use.  A source of clean fresh water should always be available.  A water bottle is probably better than a bowl, as the water is unlikely to become contaminated with cage debris.  However, if a water bottle is used, it should be cleaned, re-filled daily and checked to ensure that it is not blocked or leaking.

Rats thrive on a varied diet that includes grains, vegetables and a protein source such as dry dog food.  Good quality commercial rodent mixes are available.  Rats enjoy the occasional pieces of fruit and vegetables, but avoid peanuts and sunflower seeds, as these tend to cause skin problems.  In the wild, rats may forage for their favourite food.  By hiding and scattering food in the cage’s sawdust (in clean areas), this allows the rat to forage and hunt for his food, which will help prevent boredom and keep him occupied.  But remember, do not overfeed your rat.

A very small amount of commercial rodent mix is a good basis for a mouse diet, but be careful not to let your pets get fat.  Mice may enjoy tiny amounts of suitable vegetables and fruit, such as carrots, apples and broccoli, but avoid peanuts that can cause health problems.  Mice do not need cheese or dairy foods. 

Handling and Behaviour

Early socialisation with people plays an important part in the making of a friendly pet.

Rats are very clean, spend a lot of their time grooming and naturally live in social groups.  A same sex pair or group will be much happier, than a lone rat.  Two males, or two females, from the same litter will usually get on well and be great company for each other.  Rats enjoy “play fighting”, but if you introduce an older rat to another rat, they may fight seriously and injury themselves.  Introducing adult males to each other is not recommended, as they will fight.  Do not keep a male and female together unless you want to breed from them.   

Rats need at least an hour’s exercise outside the cage every day, but they must be supervised and you must make the room ‘rat proof’ and safe.  Keep doors and windows closed and block cracks in the floorboards, as rats can get through seemingly impassable gaps.  Keep houseplants out of the way as some are poisonous.  Electric cables should be passed through plastic piping, so that they cannot be chewed.  Alternatively, a large secure run area for daily exercise could be provided, which could be either free-standing or attached to the cage.  Always keep an eye on your rat whilst he is in is play area.  

Always approach a rat calmly and gently.  Once your rat knows you are near, place a closed fist in front of him and allow him to approach it.  If he is confident and appears interested, slowly unclench your fist and open your hand to allow him to crawl on to your palm and cup him in the palms of your two hands to ensure he is safe and won’t be dropped.  Never pick up a rat by its tail, as this can cause injury.  Alternatively, put your hand underneath its chest behind the front legs, holding firmly, but not squeezing.  Children will enjoy handling rats, but make sure they do not hold them too tightly and that they are supervised at all times.

Mice need their own kind as company and love to groom and play with each other.  Don’t try and mix  mice with pet rats or other rodents, or they may be attacked.  It is usually safe to mix female mice up to the age of about 12 weeks even if they are from different litters.  Males should ideally be from the same litter and will often fight if separated for more than a few hours and then reintroduced, or if a male is taken out to mate with a female and then put back with his companions.

Although mice are friendly and rarely bite, some may be naturally more timid than others.  Start by placing your hand quietly in the cage, holding a treat such as a piece of apple.   To pick up a mouse, hold the base, not the tip, of its tail gently, but firmly, then lift the back end gently and slide your hand under the mouse’s body.  Children should not handle mice without supervision.

Remember to wash hands after handling these rodents and between handling rodents and other pets.

Common Diseases and Ailments

Signs of ill health are frequently reflected in the external appearance of a rat or mouse: the coat becomes ruffled and starey, they eat less, are less active and lose weight.    

Red Tears – in rodents a red discharge from the nose and around the eyes can be a non specific response to stress and disease, although the redness is not blood, but a natural pigment in the mucus.  The underlying cause should be investigated by a veterinary surgeon.

Respiratory disease – respiratory disease is one of the most common problems in rats and mice.  Typical signs include rattling respiratory sounds, sneezing and nasal discharge.  Decrease stress and ensure proper levels of cage ventilation and hygiene, so that the levels of ammonia are controlled.  There a number of possible causes of respiratory problems, including bacterial or viral infections, as well as allergies.  Any respiratory symptoms should be checked by a veterinary surgeon.

Diarrhoea – sudden changes in diet can cause diarrhoea, but it is also a common sign of ill health in rats and mice and can be caused by a wide range of agents.  Overfeeding with green food is a common cause of diarrhoea.  If your rat or mouse has diarrhoea, stop feeding green food immediately and if it persists, you should take it to a veterinary surgeon straight away.

Tumours – mammary tumours, which can occur in various sites, are the most common tumour likely to occur in rats and mice.   

Overgrown teeth – it is normal for the teeth of rats and mice to have a yellowish colour, which is caused by the presence of iron pigments.  Rodents’ teeth continue to grow throughout their life, therefore they need to gnaw to keep their teeth in trim.  If there is a chipped tooth, or their teeth do not meet properly, this may cause the teeth to overgrow, which necessitates regularly trimming by a veterinary surgeon.

If you are concerned about the health of your rat or mouse, always consult a veterinary surgeon as soon as possible.

JSPCA working to

“prevent cruelty, promote knowledge, provide for aged, sick, lost and unwanted animals.”

Jersey Society for the Prevention of Cruelty to Animals (Inc.)

Founded 1868 – Incorporated 1936

89 St Saviour’s Road, St Helier, Jersey JE2 4GJ         

Tel: 01534 724331          Fax: 01534 871797

E-mail: info@jspca.org.je          Website: www.jspca.org.je

 

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