ratsRats: Care and behaviour

Pet rats live for between two and four years. They're descended from wild brown rats, which most people prefer not to find in their homes. Both pet and wild rats can cause a lot of damage, because they can climb up and get into the most unlikely places, and then chew whatever they find there, including electric cables. Wild rats can also spread disease, but domesticated rats kept under hygienic conditions are much safer. Rats are well-known as laboratory animals - they helped the psychologist B.F. Skinner to develop some ideas about how animals learn, and are also used in medical research. There are even hero rats, who help to locate unexploded mines. This is one species which evokes a whole range of human emotions. What we feel about a particular rat depends on the role it plays in our lives. As pets, rats have a lot to offer, because they can form stronger bonds with their owners than most rodents. Mice are similar to rats in being quite versatile, though they aren't as bold as rats, and tend to fight one another more.

Rat behaviour

Rats have a lot in common with humans, in that we're both opportunistic omnivores, eating whatever we find that's edible, and we're quite flexible as to what we see as 'food'. We have a similar sense of taste, and tend to like fatty and sugary foods, avoiding bitter foods that might harm us. Sometimes both rats and humans can become neophobic, or set in our ways about what food we'll eat, avoiding strange, 'foreign' foods. Both rats and humans use social learning to learn what to eat, that is, learning from one another. We tend to like food that we see others of our species enjoying, and avoid food that makes others of our species ill. Both rats and humans are social animals, and flexible in our social arrangements, the groups we live in and the sorts of families we set up. Our social organization depends a lot on the availability of resources. We also both like playing, and this applies to both adult rats and adult humans, as well as youngsters. It's not surprising that rats and humans can get on well.

So, what are the differences between us? Rats are more likely to be crepuscular, that is they tend to be active at dawn and dusk. This only applies to humans living in very hot countries, normally, humans are diurnal. Because rats tend to move about in dimly lit places, their eyes are very sensitive to light, and they can suffer retinal damage if they're forced to have their eyes open under bright lights. This applies especially to albino rats. Rats have a wider field of vision, so can see more of what's around them, but they can't see it as clearly as we can. They also have better ultrasonic hearing than we do, and talk to one another using squeaks that we can't hear, and very high-pitched sounds that we can't hear can upset them. Their sense of smell is more powerful than ours, and they have a special vomeronasal organ which allows them to learn about other rats through smell. Though both rats and humans are predators and prey animals (rats will sometimes eat smaller mammals, just as humans do), rats are less able to defend themselves, being smaller than humans, and are warier than us, tending to move alongside walls, rather than venturing out into the open.

Housing

Rats, like all rodents, like to chew, so they need a chew-proof cage and some legitimate chew objects so their teeth don't grow too long. The cage should be as large as possible, because rats are very active. A very large aquarium with a top is a possible solution. Give them branches and platforms to climb, as well as toys, like small balls, to entertain themselves with. They also need a nest box to hide in. You can use shredded paper or wood shavings as bedding - though not cedar shavings, which aren't suitable for any rodent. You need to clean out the cage once a week, leaving some bedding in the nest box so it smells right to the rat. They use one part of the cage as a toilet, and you need to clean this every day, or it will get smelly fast!

Because rats are more sensitive to sound than we are, they need to be housed away from televisions and other electrical appliances, especially if they emit high-pitched sounds. You may not be able to hear a sound that to your rat is an unbearable shriek, so assume that appliances might upset your rat, and put the cage in an appliance-free area.

Rats are social animals, so much so that they can be very upset if anything happens to another rat in their group. One experiment showed that a rat would free a trapped companion, despite researchers putting chocolate nearby to try to distract the rat. Their priority was to free their companion, and then they shared the chocolate. Rats are capable of empathy! So rats prefer to live with their own kind, and groom and play with each other.

Wild rats sometimes live in large groups, with individuals being quite promiscuous, if there are plenty of resources. When there's not much food, they tend to live in smaller groups comprised of one male and two or more females. This means that male wild rats can co-exist peacefully if there's enough space and food. A male and one or more females are more likely to get on, but rats can be prolific breeders, so you'll need to think about neutering if you want to keep a male and females together and don't want to be overwhelmed. Spaying female rats give them a health advantage that they're less likely to suffer from tumours, a common health problem for females. Rats are more likely to get on if they've known one another since they were youngsters, so you can buy two youngsters at the same time.

Rats tend to fight less than mice, both because rats tend to form more stable hierarchies (in which other rats defer to the dominant rat, without making bids for power), and because rats have more body language vocabulary to avoid fights. It's less safe to keep two male mice together. Two adult rats that don't know each other need careful introductions, letting them get used to one another's smells before you try putting them together in a neutral area. 

Feeding

Rats will eat just about anything, but you need to restrict their consumption of fatty and sugary human food, so they don't get digestive problems or become obese. Rats will do well on similar seed mixes to hamsters and gerbils, with a little fresh fruit or vegetables. Always remove uneaten fresh food after a day. Rats may also be partial to grubs and insects, wich you can buy from reptile supply stores.

Because we enjoy the same sorts of foods, owners often give their rats treats of human food, which is usually fine. Some human foods can be poisonous for rats, however, especially blue cheese and chocolate. Peanut butter and other thick, sticky foods can choke them. 

Inquisitive rats, especially youngsters, will try eating all sorts of possible edibles, so you need to supervise them when they're loose, in case they eat something poisonous. If they raid your rubbish, for example, rats may try eating potato, mango, or citrus skins, which are poisonous, especially green potato. They shouldn't have access to bulbs and corms, like amatyllis, crocus, cyclamen, daffodil, or hyacinth, and geraniums and poinsettias are also toxic if consumed by rats.

Health

Prevention is better than cure - rats are more likely to stay healthy if their cages are clean, they aren't exposed to big temperature fluctuations, and they don't indulge in human junk food! They also need to be able to chew, so their teeth don't grow too long. Check your rat's teeth regularly, to see if they need a trim. Seek advice from a vet if your rat has snuffles that it doesn't shake off . Regular vet checks are a good idea, especially with older rats, which are more prone to illness. Older females often suffer from mammary tumours. Tumours can be treated more easily if caught early, though it's safer to spay females so they're less susceptible.

Avoid buying any rat with respiratory problems, or one that just looks 'under the weather', however handsome it may be. You want a rat that looks lively. Check out its body posture for hunching or looking depressed, its eyes for discharges, its rear end for evidence of tummy upsets, and its breathing and nose for snuffles. Reliable breeders are a safer bet than pet stores, because stores have rats coming in from different locations, and diseases can easily be transmitted. It's essential to quarantine new rats in a separate room from your existing pet rats for a couple of weeks, washing your hands after handling them, so you don't introduce respiratory or other infections, which can be fatal. It's a good idea to have a vet check out any newly purchased rat, because a vet is more likely to be able to spot health problems, including mites and other skin infections.

Rats, like humans, can suffer from health problems if they're bored, or stressed out. Rats can get very bored if they're stuck in a cage most of the time with nothing much to do, so at the least, provide toys they can play with, even a toilet roll innards can provide some amusement. Unlike most rodents, rats actually like to interact with their owners, to do things with humans they trust. What can stress rats out are potential predators, like cats and dogs, and loud noises, which perhaps we can't hear. They can also be stressed by overcrowding, or suddenly having a strange adult rat dumped in their cage, and having every little millimetre of their cages cleaned - leaving some of their old bedding leaves them with a familiar, reassuring smell.

Handling

Rats are curious, and quite bold for rodents. They can make friends with their owners, but they still need some respect. Give your new rat a chance to get used to his cage when you take him home, and just let him sniff and explore your hand for a few days before picking him up. You can use titbits to tame your rat, and call him by his name when you give him a titbit, so that he's more likely to come to you when called.

Rats are less likely to get lost in the house if they're released for exercise in the same room as their cage, and know the room well enough to go back to the safety of their cage. Always supervise your rat's explorations. You can call your rat and offer a titbit if he starts to do something he shouldn't. Rats can be trained to perform various tasks, through rewarding them with their favourite foods. 

It may be tempting to take your rat outside for walks in the daytime. This is very risky for many reasons. There's a chance that the rat could get lost, or jump on the ground and be attacked by a cat or a dog. Rats are also very sensitive to bright lights. They prefer dim light, and prolonged exposure to sunlight or bright lights could cause them permanent eye damage. If you want to train your rat , do this in a dimly-lit room, and you'll get better results.

Breeding

Think carefully before allowing rats to breed, because they can have very large litters, and you can be overrun very fast. Just liking your rats isn't a good enough reason to breed from them. They need to have very good temperaments, and you need to have a lot of homes lined up waiting for them once they can leave their mother. If in doubt about your ability to find homes, or cope with finding extra space for when you separate the couple, and separate the pups from mum, don't do it! It's possible to neuter rats - talk to your vet, or just don't put males and females together.

If you're really determined to breed from your rat, do a lot of research on the nutritional needs of pregnant rats, and the care of mother and pups. Female rats aren't mature enough for breeding until they're around four months old. Giving birth may be more difficult for her if she has a first litter much after five months, and older rats have fewer pups. The gestation period lasts between 21 and 23 days and on average there are from eight to twelve in the litter, sometimes more. Rats sometimes cannibalise their pups, especially first-time mothers, or mothers suffering from stress, so make sure she's old enough to breed, and give her peace and quiet.

The pups are born blind and hairless, and their eyes open at two weeks. They're weaned at four weeks. Separate them from the mother at five weeks due to the risk of their breeding with each other or with the mother. You also need to remove the male as soon as you think the female is pregnant, due to the risk of her breeding again just after the pups are born. This is why you need a lot of cages and space if you breed rats! It's a good idea to handle baby rats from when they are two weeks old, because they're more easily tamed when young. Again, you need a lot of time to spend on taming your rats, so they'll fit into their new homes. There are plenty of rats looking for good homes, so the most sensible decision is usually not to breed.

Further reading:

Ben-Ami Bartal I, Decety J, Mason P.(2011) Empathy and pro-social behavior in rats. Science. Dec 9;334(6061):1427-30

Berdoy M, Drickamer LC. (2007) Comparative social organization and life history of Rattus and Mus In: Sherman PW, Wolff JO, editors. Rodent ... Chicago, Illinois: The University of Chicago Press.

Burn CC (2008) 'What is it like to be a rat? Rat sensory perception and its implications for experimental design and rat welfare'. Applied Animal Behaviour Science 112: p1-32

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