Fancy Mice: Boys or Girls?
Girls
Female mice are known as Does. They must have same-sex company. They live together happily in small groups, with a minimum of 3 being recommended. It is good to have a mixture of ages to allow for younger girls to learn from older ones, as well as to ensure you don't have multiple deaths at a similar time. Since introducing new mice is a fairly smooth process for Does it is simple to keep a colony of mice as an ongoing situation.
Female mice tend to enjoy climbing more than the boys, therefore benefit more from climbing enrichment such as ropes and ladders. They can be quicker and more active than boys, making them less likely to stay still and more interested in exploring when being handled.
Boys
Male mice are known as bucks. They also need company, as a solitary Buck can get depressed. Male mice are harder to keep in stable groups once they reach sexual maturity and fights are common. Aggression can be seen through actions like tail-rattling and persistent chasing.
It is possible to keep male mice together upon adulthood but this is recommended for experienced rodent keepers only. Cage size, frequency of cleanouts and even the toys available must be monitored and restricted. Many keepers choose to do partial cleanouts of boys to ensure some of their scent remains.
Neutering Bucks can be the best option for them. This allows neutered bucks to live together with intact males more safely, or after a period of 6 weeks to allow hormones to die down, a neutered buck can be introduced to a group of females without the risk of impregnating. Some boys will still mount the girls, but this is safe once the waiting period is over.
Neutering does have risks but with a trusted vet and a healthy buck of a good weight, these are low and this does give your Buck a better chance at happiness.
Male mice do have a stronger and very noticable musk, more obvious in those intact. People have different reactions to this but it certainly isn't a scent you will not notice. It is best to visit a household with male mice to get an idea of your own reaction to this.
Why give boys a chance?
Male mice stay longer in rescue, with many never finding homes due to the misinformation around them. They do not have to live alone and with good practice and care they can live in small groups providing they are given enough space and enrichment and care is taken with cleanouts. Intact males can be introduced to Multimammate Mice if other options are not available. This is an easy introduction and has no pregnancy risk.
Neutered boys have even more options, with larger rescues able to fund the neutering costs before offering them for homing. A neutered boy, or multiple, can integrate well within an existing female group.
Male mice are often calmer than the girls, and so will be happier to stay still when handled. This can lead to stronger bonds with their owner.
Fancy Mice Introductions
Introducing new mice is quite easy providing you know the right way to do it. The following advice is for female fancy mice or neutered male to female group only. Please do not apply this to any other rodent. Each rodent has different criteria, and it can be extremely dangerous to them to follow the wrong advice. Gerbils for instance may kill each other if you do not introduce safely via the Split-cage method.
Mice must have company, and a group of at least three is recommended. This means that in the sad event of one dying early, you are not left with a lonely mouse.
Male mice can be neutered, and after 6 weeks from their operation date has passed, they can be introduced to girls following these instructions. Although you can cohabit neutered and intact bucks together, this is more risky, and should only be done by experienced mice keepers.
Getting new mice
This is best done from rescue or breeder due to risk of supporting rodent farms.
If you are mixing the larger show mice, with fancy mice, then your introduction will be more complicated however, it still has a high chance of working.
Be careful when choosing your mice, as if you already have several dominant mice in your cage then you may need to ask your breeder/rescue for a more docile animal.
You may want to quarantine new mice before introducing, for a period of a few days or weeks. This will only be effective if you have a place to keep them that does not share the same airspace as your current mice. You will also need to be very careful about washing your hands and the equipment used whilst doing this.
Unlike gerbils, mice should be introduced on a neutral territory. A small tank or carrier, is ideal, with a minimum of substrate and no toys. Add two water bottles or bowls, and either two food bowls or try scatterfeeding. This means one mouse cannot claim one bottle/bowl and prevent the others from feeding.
You may wish to mark all mice with vanilla essence to help conceal their natural scent and aid the intro.
Add your mice into the tank and watch carefully! It is quite likely the one mouse will do the majority of chasing, so this may well be your alpha female. Chasing, squeaking, and same-sex mounting is all fine. Mice do squabble, even when they've been an established group for years.
If the numbers of the new mice is less than your established group, it can sometimes help to allow them to use the tank first. This means that they can establish their scent across it first which will unbalance the larger group and make them less likely to fight.
You only need to separate if blood is drawn. If this happens, make sure you separate out the bully, and not the victim. Leave them apart for around 30 minutes to cool down and start again later on the neutral territory. Some mouse introductions may never be successful, although this is quite rare.
Monitor them for a good few hours and if things are going positively then add a single item. Rather than a silent spinner wheel, a flying saucer is ideal for groups of mice as several can use it at once so it reduces fighting. Equally, if you do add a nest make sure it is easily large enough to accommodate all.
Scrub and disinfect the cage they will all be in and do not leave any toys or furnishings. Double up on any food/water bowls as above. It might help to transfer some of the bedding from your neutral territory tank.
Move your mice to the new cage. It can be good sometimes to allow your new mice around ten minutes or so in this cage before your established mice, as this gives them a chance to explore and get their scents marked.
You can add items gradually to their cage over the course of the next few days, make sure to keep doubling up on food and water bowls until you are sure that a single mouse does not camp one and prevent the others from feeding. You may also want to weigh all mice on a weekly basis to keep track, that way you will know if one is suddenly being bullied.
After a week or so, depending on their behaviour, you can be back to a fully furnished cage such as the picture to the right.
Health & Illness in Fancy Mice
An ill pet mouse can happen very rapidly and it is important to keep an eye on your mice. As prey animals, by the time you notice a problem it can often be quite serious as they hide their pain. Keep a mite spray handy for any excessive scratching you notice. Make sure you know what the normal behaviour is so you can identify anything out of character and try to handle your mice regularly so you will notice any problems in breathing or movement.
Signs of illness include:
- Poor coat condition, posture
- Sudden weight loss
- Squeaky, laboured or otherwise noisy breathing.
- Lethargic and cool to the touch
- Lack of interest in food or water
- Diarrhoea or constipation
- Excessive scratching
If your pet mouse has lost weight then see this list of tempting foods for ill mice. A healthy pet mouse should weigh between 30-40g although this can vary.
An ill pet mouse will be cared for by its companions so do not separate them. It is always worth taking at least one friend with them on any vet trips and unless absolutely necessary keep them together once returned. A lonely mouse will find it harder to recover and may even die from depression. Below is a list of the more common illnesses in pet mice:
Barbering
Barberism in fancy mice is caused when one mouse overgrooms another to the extent that it causes bare patches in their coat. This can also involve nibbling at whiskers or tail tips.
Diarrhoea
Diarrhoea in mice can be treated by sprinkling Arrowroot powder over their normal food. Arrowroot can be obtained from most herbal food shops or your local supermarket. It is also important to ensure your mice are kept well hydrated so check their water bottles and bowls. A common cause of diarrhoea in mice is too many green vegetables in their diet.
Tumours/Lumps
Lumps in female mice are sadly quite common and can be a variety of issues, such as an abscess (often caused by fighting), polyp, prolapse or a cancerous tumour. Lumps can be removed at a trustworthy vets however some research suggests that they have a very high possibility of recurrence as there is a chemical in the lumps that prevent others occurring.
Abscesses are generally softer than cancerous lumps and can be drained by your vet. A mouse with a lump may still have many months of life left, depending on its location and does not need to be put to sleep until it begins showing signs of pain or unhappiness.
Scratching/Skin problems
Excessive scratching or grooming can led to serious skin problems. This can be caused by Mites, and the affected mouse may display anything from mild scratching to severe, with patchy hair and skin ulcerations. Beaphar spot-on can be a good treatment, bearing in mind adjustment must be made for the weight of your mouse. More serious causes of mites may require your vet to perscribe something such as Ivermectin.
Another cause of habitual scratching could be boredom, see our section on enrichment and general care for ideas of how to keep your mice happy. You may also want to consider changing your substrate as some mice can have allergies to a specific type.
Teeth problems
Like any rodent, a mouse's teeth are constantly growing so you must provide material to help wear it down. Occasionally a mouse with a jawbone or teeth abnormality may need regular trips to a vet to trim their teeth.
Handling & Taming Fancy Mice
Handling pet mice is easily done especially if you have obtained them from a good rescue centre or ethical breeder. Some mice can be shy but most will become used to you over time.
Give your new mice time to settle in to their new environment and interact with them by talking to them and offering treats through the bars of your cage. Please note that taming your mice will be much harder if you have a tank as you approach your mice from above which is what a predator would do. Taming your mice will also very difficult if they are stressed by a too small or unsuitable cage such as Rotastak. See details on pet mice environment for details.
Handling pet mice can begin after a few days, try exclusively hand-feeding certain treats such as millet, pumpkin seeds and dried mealworms. They will soon learn that they must approach you to obtain these. Leave your hand resting on the cage floor and wait for them to start sniffing and climb on your hand. You can then gently lift this up and bring them out.
Other mice may need to be trained to enter a toilet tub or container that you place in their cage so you can lift up once they are inside. Make sure you block both ends as you lift. Pet mice may occasionally nip if frightened or handled roughly but this is rare.
Unlike some rodents, mice can safely be held by their tail if needed. This should only be done if other options fail and you must hold at the very base of their tail and support the rest of their body to avoid injury.