Choose a Healthy Pet
Even before you buy your rat, or add another one to your colony, you can help prevent diseases. If you are buying your first rat, make sure that it looks healthy. It should be active, have a shiny coat that has no bald patches, and not have a runny nose or eyes. Even if it looks healthy, though, it could be carrying any number of diseases that you don't know about. If you notice any other rats in the same cage that don't look healthy, it's probably best to look somewhere else. The best places to buy healthy rats from are breeders, because they are very knowledgeable in the subject and monitor their rats for any signs of illness. If you are bringing a new rat home to join your other rats, it is a good idea to keep it in quarantine (a cage all by itself ) for at least a week or two (longer if symptoms of an illness develop) so you can observe its behaviour before determining if it is fit to join the rest of your colony.
Buy and Keep Clean Food
No matter what you feed your critters, it should be fresh, clean, and free from dust or mould. There also shouldn't be any bugs such as mealworms in the food, either. If you buy the pre-packaged food (in sealed bags) you should be safe. If you buy food in bulk, check the food carefully for signs of spoilage. Make sure there's a lid on the bulk bin so that there's no way dust could have gotten in. The food also should smell nice. If it doesn't, then something's probably wrong. If you happen to find any bugs, mould, or any other impurities in the food you have bought, throw it away immediately, or go back and ask for a refund.
After purchasing the food, you should store it in a cool, dry place, preferably in a resealable container such as a Tupperware or old margarine container. Make sure it doesn't get wet. Also, watch where the food goes after you give it to the rats. Some rats like to urinate in their food dishes, and that can really contaminate the food. If you see any pieces of food left in urine, dispose of them immediately.
Keep The Cage Clean
Rat urine contains ammonia which is toxic for them even just to breathe in. The bedding should be changed at least once a week or more often if necessary, and the cage washed thoroughly with warm water. Toys should be cleaned once every two weeks or more often, depending on the number of rodents and the size of the cage. It's also important to have good ventilation in the cage, too. Wire-barred cages are good for this, as they allow air to flow through. As a result, they can be cleaned slightly less often than aquariums. Aquariums, especially ones with lids, don't allow air through as much as wire cages do, so the ammonia vapor from the urine sits at the bottom of the cage and can irritate the rat's immune system and cause infection or even death if the cage is never cleaned. Aquariums should be cleaned more often and more thoroughly for this reason.
Quarantine New Rats
Whenever you get a new rat, or take your rats to a place where there are other rats, you should quarantine them from the rest of your rats for at least 3 weeks, more if you notice any suspicious behaviour. Even if the new rats seem fine, they could still be carrying a disease that simply hasn’t shown up yet. If the rats are healthy after the 3 weeks are up, they should be safe to put with your other rats. If you notice any symptoms of illness in those 3 weeks, keep the rats quarantined until they are better.
It is also a good idea to, when coming home from a place where there are other rats, change your clothes and take a shower before playing with your rats, just in case you have contaminants on your body from other rats. It seems like a lot of precaution, but it is better to be safe than sorry, especially with the unfortunate short life of rats.
