Don't let this page scare you! Keeping ratties is really not hard - and most of the things suggested here are just common sense!
Give your ratties as much space as you possibly can! The more space they have, the happier, livelier and more fun your ratties will be. They're also less likely to get fat, and less likely to get ratty with each other (boom boom).
Ours are mostly in purpose built cages, the one pictured is made from Ikea shelves
with wire doors. The shelves are the cubic type, so each unit has four 'rooms',
measuring 40x40x40cms. As a rough guide, we allow one room for each girl rat,
two for each boy. Although no rat should be in a total area less than two rooms.
We like this arrangement as the floors are coated wood (i.e. 'beech effect')
so it's very easy to clean, the four doors cover the whole front of the cage,
and we've made one door drop-down, so the ratties can come out to see us even
when we don't have time to let the have a proper run-around.We've used one Ikea
door to make a dark sleeping area. It is also flexible - two cages can
be joined together to make eight 'rooms', or a rat confined to just two (which
we had to do when it looked as if Simone was contemplating having her babies
on a high shelf!).
The doors are closed with both catches and magnets, everything covered with non-toxic varnish and extra shelves made from the pieces of wood cut out for access holes between rooms.
If you don't want to make your own cage (and it has taken us many attempts to get good at cage-building) there are plenty of good cages on the market, but think big - they should have room for their bed, food, loo-corner and toys. Rats also shouldn't sit on wire as it's bad for their feet - so no wire floors and keep wire shelves to a minimum. Plastic bottoms are better than metal for longevity. Also, some cages are designed with no thought to how you are to get a big rat *out*! Make sure the doors are fairly big, and in convenient places.
Rats are very clever, very mischevious and great fun. A bored rat is grouchy, likely to squabble with their friends, get sick easier and be a lot less interesting as a pet. It's not hard to keep a rat occupied - they can find the most bizarre things fun. There are plenty of toys on the market for small animals - rats will play with those made for just about any animal out there. In addition it is easy to make fun things - hammer a few bits of wood together and hey presto, a climbing frame. Old knickers (minus the elastic as they could eat it) make a fun hammock-cum-swing. Cardboard boxes (minus the tape), tubes and coat-hangers can all be turned into hours of fun. Use a bit of common sense - if it's not safe to eat and they might eat it, don't give it to them (hence be careful with rubber things and elastic). If it has sharp pointy bits they could fall on, file them off or cover them over. Oh, and make their bed comfy - rats (especially rats raised in our house!) like to be pampered. Take a look at the links page for things to buy ratties.
There are lots of rat foods on the market - which one to use will depend on which your rats prefer. We mix our own rat food from rabbit food, dog kibble (we like burns), dried pasta and breakfast cereal (but check for sugar content). This is based on the Shunamite Diet. In addition rats need fresh food - pretty much anything apart from citrus fruit is fine. Ours particularly like sweetcorn, carrot tops (the green bit), kale, blueberries and fresh peas. Bread, pasta, rice, cous-cous, porridge - all make good additions to the ratty diet. Some people have found that too much protein gives older ratties spots, in which case just reduce the cheese, eggs, meat etc. Baby rats should be given eggy-porridgy supplements for a while, to make sure they grow big and strong. (We give them egg food meant for birds mixed with complan) plus lots of fresh calcium-rich green leafy veg like kale. If your rat is getting fat, cut down on their non-fruit and veg food, but keep a good balance. Rats are notoriously good at eating anything. We live in NW london, so ours regularly get a little bit of leftover curry. Not sure we'd go as far as recommending it though....but ours love it :)
Rats don't like to be on their own. Especially girls - a girl on her own is usually very miserable indeed. They should have a friend fairly close to their own age, even if they're in a big group. Boys can be kept on their own, although undoubtedly prefer to have a ratty friend. Some boys can be a bit grouchy, especially if they've been introduced to their ratty friends when a bit older, in which case it may be necessary to keep them on their own. Another option, especially if they appear lonely or you've not got enough time to keep them company (when on their own, they'll rely on their humans for all their social interaction) one option is to have them castrated and put them with the girls. I have never seen a castrated boy not get along with the girls, who usually spoil him rotten! Unless you want babies, NEVER allow boy and girl rats to play together beyond five or six weeks old.
Is your girl suitable? Girl ratties don't need to be mums - in fact, being a mum puts a big strain on the girl and can make her quite fed up and thin. They can have over 20 babies (our record is 22), all of which need lots of love and attention from their humans if they are to make good pets. At the time of writing, Simone's babies are nearly three weeks old and are running riot. She is having to sleep on a high shelf to keep away from them, as being bombarded by 16 hungry babies as soon as you step foot on the ground is not fun. We are feeding her as much food as she wants - porridge, complan, pasta, bread-n-milk etc. The babies have just started on their eggy-complan as a supplement to mum's milk. Simone is a big, healthy girl - anything less and the babies would be just too much. There is always the risk you could lose your girl when she gives birth - or that something could go wrong afterwards and you need to hand-rear the babies (that means feeds every two hours, and almost no chance they'll all survive).
Do you have time? As Simone's had 16, if they are to be socialised well, we need to spend a couple of hours with the babies per day at least - I was up until 1am a couple of days ago as I'd got home from work a late. You will need to provide a baby-safe environment for them to grow up in, extra toys and food. As mentioned above, there is always the chance you'll be up every two hours hand-rearing them should something go wrong.
Can you re-home them? Don't take babies to pet shops - the chance they'll go as snake food is very high. Snakes are becoming more and more popular, and a lovely treat for them is a bouncy little rat to hunt or, if the rat is lucky, a freshly knocked-out one. Even if they don't go as snake food, they could be bought by anyone, regardless of whether they are able to look after them or not. In the past we've taken ratties to 'good' pet shops, but now for peace-of-mind, we only sell them privately. There are hundreds of rats abandoned each year, and unlike dogs and cats, many animal rescues don't guarantee not to end up putting them to sleep. You don't want one of your beautiful babies to end up like Paddy and Sean who we rescued a few years ago - kept in the back garden in a cast-iron incinerator thing about the size of a carry-box, on months-old newspaper, so dirty we thought they were both agouti - they turned out to be hoodies! So, you'll need to rely on rehoming them through adverts, the NFRS or other rat societies or at shows. If you don't manage to find homes for them all, you'll need to find room for them at home. Always have a worst-case scenario back up plan.
If you've said 'yes' to all of the above, then an extra thing to consider, and one which will involve a little bit of research is genetics. The hardest rats to re-home are agoutis or blacks (as people think they look like wild rats, and because they are fairly common). One way to get around this is to go for marked ratties, this way even if you end up with agouti babies, they'll not look 'wild'! (n.b. even if neither your mummy or daddy rat is agouti, you can still get a whole litter of agouti babies as it is a dominant gene, and if carried, you'll need either two recessive genes of certain other colours, or a 'diluting' gene such as ruby-eyes). One good way of working out what you'll get, is making sure you know as much about the history of the parents as possible - what colour their parents and siblings were. Getting a rat from someone who breeds to show will probably give you less 'wild cards' in your ratties genes, so you can be more certain what you'll get. Also take into account the health of the family - if the parents of your ratties have developed tumours really early, or another problem that could be inherited, it's best to avoid risking passing this on. Get in touch with the people you got your ratties from - they'll be able to give you a lot of help. Many breeders have websites that will also be a good source of information.
Will you be able to take your rat to a vet should they get sick? If not, then just don't get one - it is not fair to keep a ratty who badly needs treatment, be that antibiotics or an operation. And vet bills can be a lot. The two big things rats tend to develop are the wheezies (will probably re-occur again and again once started, but antibiotics can keep it under control), and tumours. Most tumours are benign, in which case they are usually 'flabby' and won't interfere too much with organs etc., but will cause discomfort so are best removed. Malignant tumours need whipping out asap to prevent them spreading, and possibly followed up by tamoxifen to help the rat recover. Most vets *are not* rat friendly - the first we took a ratty to was so afraid, he managed to push the needle through the scruff and out the other side, spraying antibiotics over the table. To find out, don't ask the vet if they can treat rats (as technically, all vets can), ask if they've treated them in the past, how often and whether they're happy doing so. If you live near another ratty person, ask where they take their rats.
We have put £200 aside for each ratty we own for vet's bills. Sometimes the vets bills for an individual rat can be more than that or alternatively you might be lucky and not have to go to the vet at all.
Keeping your ratty's cage clean and dry, keeping them on paper-shavings (we use 'safe bed', bio-catalet cat litter and other similar products) not sawdust and maximising ventilation (if you must keep them in a glass tank, make it a wire lid) will help to guard against preventable ratty ailments. Also use your common sense - a good, balanced diet, exercise and perhaps vitamin supplements, just like in people, will help a lot.