Category: rodents

Mice and rats: housing

Proper housing is a major factor in the maintenance of healthy mice and rats. The psychosocial well-being of the animals must be a primary consideration. Mice and rats can be housed within enclosures made of wire, stainless steel, durable plastic or glass.

Stainless steel, durable plastic or glass are preferred materials for a rodent enclosure because they resist corrosion. Wood and similar materials should not be used in the construction of enclosures because they are difficult to clean and cannot withstand the destructive gnawing of rodents.

The construction and design of the enclosure must ensure that the residents cannot escape! Furthermore, the enclosure must be free of sharp edges and other potential hazards. The enclosure must be roomy enough to allow the rodents to pursue normal movement and breeding activity, if the latter is desired. Visual security, i.e. a place into or under which the rodents can retreat for privacy, should be provided, as well as exercise wheels for optimum mental and physical health. Rats, in particular, tend to be burrowers and seem to enjoy hiding under things for extended periods.

Enclosures should be easy to clean, well lit and adequately ventilated. Bedding must be clean, non-toxic, absorbent, relatively dust-free and easy to replace. Shredded paper, hardwood shavings and processed corn cobs are preferred bedding materials. Tissue paper or cotton are often supplied to breeding rats for nest-building material.

Cedar shavings should be avoided as the aromatic oils in the cedar are toxic to animals. Pet mice and rats seem most comfortable when they are spared exposure to excessive noise, needless excitement and confusion, and other similar or perceived stresses. Sudden environmental temperature changes should also be prevented because pet rodents do not tolerate them well.

The frequency with which the enclosure should be cleaned depends on its design, the materials out of which it is made, and the number of rodents within. As a general rule of thumb, however, the enclosure and all cage “furniture” should be cleaned and disinfected once weekly.

The food and water containers should be cleaned and disinfected once a day. More than one set of containers should be maintained, and the soiled set should be washed in a dishwasher, if possible. Vigorous scrubbing of the enclosure and “furniture” with hot water and soap and a thorough rinse should be followed by the use of a disinfectant. Vinegar is often required to remove the scale deposited by rodent urine.

Rats and mice are especially sensitive to the irritating effects of ammonia. This chemical builds up quickly in the bedding from the relatively large volume of urine excreted by pet mice and rats. Bedding must be changed 2-3 times each week, or more often if necessary. Furthermore, ventilation must be adequate to reduce or eliminate the irritating effects of ammonia on the respiratory lining of pet rodents.

Mice and rats: feeding a healthy diet

The mice we keep as pets are the same species as the house mouse. They live alongside human beings nearly all over the world, eating what they can find. Rats are designed to eat plants, e.g. seeds, roots, nuts and fruit. The cheek teeth of the rat are more like our own than the teeth of rabbits or guinea pigs. They don’t keep growing throughout the animal’s life, but like ours, they erupt when the animal is young and have to last it all its life. The incisors are constantly growing and wearing against each other to form the characteristic chisel shape. Rats like to gnaw to keep their teeth in trim and because their natural diet would demand it; do not chop or grate vegetables too finely but let them gnaw pieces off themselves.

Mice are ‘omnivores’, which means that, like us, they have evolved to eat mainly vegetable matter, but to keep in good health require some food of animal origin as well. The best commercial small mammal mix to feed your mice would be one that is sold in sealed packets, so it remains fresh, and that contains some protein of animal origin (look at the label on the back of the packet for this information).

Fresh food

Mice will eat fresh food too; they will eat almost anything, but to keep them in the best of health feed a selection of bits of fruit and vegetables each day – try different ones to see what their favourites are. You can also feed things like dried fruits, pieces of toast, pasta and rice. Some mice like sweet things like fruit yoghurts, but these should be small amounts and only occasionally to prevent obesity.

Cheese and meat

Mice are famous for being mad about cheese, although people who don’t like mice find that they catch more if they bait a trap with bread instead! However, you can certainly try your mice with cheese and meat. Another good source of protein is eggs.

Foods to avoid

To keep your mice in good health, you should avoid feeding too much food containing lots of sugar, for example sweet biscuits or chocolate. You should also avoid feeding anything that is high in fat.

Rats are ‘omnivores’, which means that, like us, they have evolved to eat mainly vegetable matter, but to keep in good health require some food of animal origin as well. There are some very good rat mixes on the market. You should always supplement your rat’s diet with a good selection of fresh food including fruits and vegetables, pieces of hard-boiled egg, cheese, they will even eat the dregs from your yoghurt pot!

Commercial mixes

Firstly look at the label; the protein level should be in the mid- to high-teens (15-18%), and some of that should be animal protein. Mixes that are predominately seeds and peanuts will make the rat fat but unhealthy. Make sure the pack is within its sell-by date. Secondly look at the mix; it should smell fresh and not be dusty. It is better to buy a packaged mix rather than a loose mix from a large bin – this will ensure freshness.

A good commercial mix has been well thought out and provides all the nutrients the rat needs for a long and healthy life. Many pet rats are fed on the same food as their owners, and seem to be remarkably healthy. Some people even alter their shopping habits to keep their rats on a healthy diet! A rat that starts the day with a bowl of cereal, some toast and a bit of fruit, and has bread, fruit and vegetables to nibble during the day, and shares your supper at night could live a long and healthy rat life!


Some owners feed their rats the sort of pellets fed to laboratory rats. They need to be fit and well, and the pellets they are fed provide a balanced diet.


If you know a treat would be good for you, it will also be good for your rat. So, if you eat a healthy diet, anything you consider to be healthy for you will be healthy for your rat. Try to avoid food that is very sweet, fatty or salty. However, it is very easy to produce a fat rat as they are so much smaller than us – one peanut provides a great proportion of their calories for the day. Seeds and nuts should therefore be kept to a minimum of 1 or 2 peanuts and sunflower seeds per day.

Can poor diet lead to disease in rats?

Obesity in pet rats is a known problem. Plenty of exercise with limited access top chocolate biscuits and high fat seeds will prevent this problem. Wild rats have evolved to be survivors, and can survive even on a poor diet, but there is no doubt that a good and varied diet makes for a healthy pet rat, with increased resistance to disease.

Mice and rats: a history

Domestically raised mice and rats are popular pets these days; they are readily available, relatively inexpensive and easy to care for, and usually enjoy human handling.

These animals have been used extensively in research laboratories for many years. Consequently, their medical problems (many of which are inherited disorders resulting from intensive inbreeding) have been traditionally approached on a group basis rather than on an individual basis.

As a result, very little practical and useful information exists on the medical care and treatment of individual pet mice and rats. Furthermore, even less information is available to the pet owner on responsible home care of murine rodents and recognition of their potential medical problems.

The mouse, bearing the scientific name Mus musculus – interestingly, the Great Blue Whale’s scientific name is Balenoptera musculus – is thought to have originated in Asia. Its tremendous adaptability, long-time association with people and our dwellings, and unbelievably prolific breeding potential (one reference cites one million descendants from one breeding pair in 1 1/2 years) has allowed mice to enjoy a worldwide distribution.

Mice are timid, social and territorial animals that spend a disproportionate amount of time in the wild pursuing an omnivorous (animal and plant material) diet. Feeding is most often carried out at night to escape predation. Laboratory and pet mice are not strictly nocturnal (night-active) but tend to exhibit alternating periods of activity and rest throughout the day and night.

In the wild, mice may exhibit aggression among themselves, though establishment of a social “pecking order” tends to reduce this potentially injurious behaviour. Individual males apparently dominate groups of mice using this social pecking order, and females with litters may fight to defend their nests.

Domestication and intensive breeding of mice have resulted in a tremendous genetic diversity of mouse populations. The Swiss Albino mouse has become one of the most popular strains for pets but many others are commonly seen.

  • Scientific name: Mus musculus
  • Life Span: 2-3 years
  • Potential Life Span: 4 years
  • Desirable environmental temperature range: 18-27°C/65-80°F (20-22°C/68-72°F optimum)
  • Desirable relative humidity range: 30-70%
  • Age at onset of puberty: 28-40 days
  • Estrous (heat) cycle length: 4-5 days
  • Estrous length (period during which female is receptive to male for copulation): 12 hours
  • Gestation (pregnancy) period: 19-21 days
  • Average litter size: 10-12 (1st litter usually smaller)
  • Weaning age: 21-28 days

The rat, bearing the scientific name Rattus norvegicus, apparently also originated in central Asia. Rats were domesticated in the 17th century and the process has continued to the present, resulting in many breeds that are docile which makes them great pets.

Rats, like mice, have been used extensively in biomedical research. Most of the tremendous number of breeds and strains currently in existence have resulted from intensive inbreeding efforts by research laboratories over the years.

Wild rats are found in all kinds of habitats and nearly all land masses of the world, an enduring tribute to their adaptability and their long-time association with people.

They tend to be omnivorous (feed on plant and animal material) but exhibit tremendous opportunism in their feeding habits when living in and around human dwellings.

Wild rats tend to be nocturnal (night-active) animals but often use daylight hours to forage for food. Laboratory rats, like laboratory mice, on the other hand, are not strictly nocturnal. Mice and rats are both relatively short-lived animals, which can be disconcerting to owners of these pets.

Some, however, feel that having their children experience the relatively short period of companionship and subsequent death of pet mice and rats is a meaningful way to expose children to the “ups and downs” of life.

Hamsters: feeding a healthy diet

You should ensure your hamster has access to good quality food and fresh, clean water at all times. The exact nutritional requirements of the hamster are not known, but in the wild they are ‘omnivores’ meaning that they eat both vegetarian food (plants, fruit, vegetables and seeds) and animal protein (usually insects). Unfortunately, most hamster mixes are entirely vegetable matter, without any animal protein; many of these mixes are also very low in some vitamins and substances called ‘essential fatty acids’ that are especially important for a healthy skin and coat.

Pet hamsters are best fed a commercial diet containing at least 16% crude protein. These foods are usually available as dry blocks or pellets. Make sure you choose a really good one and supplement it by adding lots of healthy bits and pieces. If something’s good and healthy for you, it will be just as healthy for your hamster.

You can feed lots of different fruits and vegetables, use whatever you have available at home each day – make sure these are thoroughly washed to avoid exposing your hamster to pesticide residues and possible bacterial contamination. You can also feed small pieces of stale bread or toast, and sugar-free cereal. Why not try some left over pasta, rice or potato, bits of meat, cheese or chopped boiled egg? You can also feed your hamster live insects, but this is not always possible. Hamsters also like sweet things, so you could see if your hamster likes a spoonful of fruit yoghurt. Some things he will like, but others he won’t, it will be a case of trial and error.

The best hamster mixes are those that contain animal protein. These are sold in sealed packs, with a sell by date on them, this ensures the food is fresh and you can also check the vitamin content on the packet. When buying this type of hamster food, be sure to buy small quantities, this will ensure the food is always fresh. Once you have opened a new packet, store it in an airtight, insect-proof container. Even on the best hamster mix, your pet will benefit from some fresh food too.

Hamsters can never be given ‘too much’ fruit or vegetables, however, be aware that if your hamster stores his food, any fresh food will go mouldy, so make sure you clean his home out daily to avoid this from happening.

It has been purported that meat and even onions can makes hamsters savage – this is of course untrue. However, no hamster likes having his favourite food being taken away, just like a dog with a juicy bone!

If you want to give your hamster live insects, you will need to find a pet shop that specialises in reptile feeds. Lots of small lizards have to be fed on live insects, and things like mealworms and crickets are bred for this purpose. If you get insects from a shop, you can be sure they’ve had no contact with insecticides or other harmful chemicals. Crickets are better than mealworms for two reasons:

  1. Mealworms just sit there, but the hamster gets exercise chasing the more active crickets.
  2. Mealworms are very, very low in calcium, which is essential for good bone strength – if hamsters eat too many mealworms, it can upset their calcium balance.

Feeding live insects is probably only possible if you keep your hamster in a big aquarium tank. If you don’t feed live insects, try cheese, meat, egg or yoghurt.

Pet shops and stores sell prepared hamster diets available in boxes or bags. These diets contain large quantities of seeds and items rich in oils.

Consequently, if improperly stored, they become rancid and lose their nutritive value. Furthermore, these oil-rich items promote obesity.

These types of foods can be offered as a supplement to the commercial diets mentioned above. All food should be provided in heavy ceramic dishes that resist tipping. The sides of the dishes should be high enough to keep bedding and faecal material out of the food, or the dishes should be elevated slightly above the bedding. Water is most easily made available and kept free from contamination by providing it in one or more water bottles equipped with ‘sipper’ tubes.

Make certain the ends of the tubes are positioned low enough to allow all residents within the enclosure, especially juvenile hamsters over 1 week old, easy access to them. Also make certain that very young hamsters are strong enough to obtain water from these sipper tubes.

Hamsters: dental problems

Hamsters’ incisor (front, gnawing) teeth grow continuously throughout their life; as is true for all rodents. The incisors receive continuous wear as the uppers and lowers contact each other, preventing overgrowth.

Misalignment of either the upper or lower incisors because of previous injury, abscess formation or malnutrition may result in overgrowth of one or more of the teeth.

Overgrown incisor teeth usually cause serious injury to the roof of the mouth. Sometimes the lower incisors actually grow through the roof of the mouth and into the nasal cavity.

Initial signs of this problem are poor appetite and drooling; total lack of eating, weight loss and a foul odour from the mouth may be noted later.

If you notice any of these signs, you should take your hamster to see your vet.

If the incisors are overgrown your vet can carefully trim them and extract them from the roof of the mouth. Antibiotics are prescribed because of the high probability of infection following this type of injury.

Periodic trimming of the incisors is usually necessary for the remainder of the hamster’s life.

Hamsters: cancer

Cancer is very common in pet hamsters. The incidence increases with age, as is the case with most animals, and is higher among females than males because of the variety of cancers that involve the female reproductive tract.

Tumours of hamsters may be benign or malignant and they are vulnerable to an unusually large number and variety of benign cancers.

Cancers involving hormone-producing organs, such as the thyroid and adrenal glands, are among the most common tumours found in hamsters. These cancers cause hormone imbalances, hair loss and changes in behaviour, as well as other significant signs.

If your hamster has a small external tumour, it is possible for your vet to perform surgery to completely remove it.

Internal tumors, however, are much more difficult to diagnose and remove. The small size of the patient, the even smaller size of the organs involved, the sometimes inaccessibility of the tumour, and the expense involved are some of the reasons why an owner of a pet hamster might elect for euthanasia (putting the pet to sleep) or maybe even do nothing, allowing the hamster to live out its life instead of performing surgery in these situations.

Hamsters: breeding

The sex of adult hamsters is easy to determine. Males have very large, prominent testicles. In fact, owners unaccustomed to seeing them are often astonished at these anatomic peculiarities.

Male golden hamsters can breed from 14 weeks old, and females can be bred when they reach 10 weeks old.

When the female is ready to mate, thin, stringy, cobweb-like mucous is visible from the vulva. The female can then be placed into the male’s cage about one hour before dark. The pair must then be carefully observed for mating activity and/or fighting.

Females can be very aggressive to males in this situation and can harm them, so the male should be removed at once if there is fighting. Because fighting is highly likely, aggressive males are best hand-mated so they are better able to defend themselves and “hold their ground”. The male should then be removed after mating.

Pregnancy lasts about 16 days.

Before delivery, the female becomes restless and usually discharges a small amount of blood from her vulva.

Litters usually range from 5-10 pups – the pups are born hairless, with ears and eyes closed. They do, however, have their front teeth (the incisors) at birth.

Female hamsters with young must be provided with abundant nesting and bedding materials, and plenty of food and water, and they must not be disturbed in any way.

The young should not be touched or handled until they are at least 7 days old, the nest should not be disturbed, and the cage should not be cleaned during this period. Failure to heed these cautions, especially with females nursing their first litters, most often results in cannibalism of the young.

Observant owners may note an interesting maternal rearing activity, especially if the female with young is excited or disturbed. She will stuff pups into her cheek pouches and deposit them into the nest a short time later when she believes the danger has passed. Occasionally, pups suffocate as a result of this activity, especially during lengthy periods of disturbance.

Young hamsters usually begin eating solid food at 10 days of age but are usually weaned at about 3 weeks of age. Solid, pelleted food must be soaked to soften it and be placed on or near floor level of the enclosure for easy access by the weanlings.

Sipper tubes must be positioned low enough so that the smallest pups can reach them. Some pups will not be strong enough to extract water from sipper tubes, so you must be vigilant for this potential problem and provide an alternative water source for them.

Hamsters: bladder stones

Hamsters are susceptible to the formation of stones within the urinary tract. The bladder is the only location within the urinary tract in which stones would likely be detected on physical examination by your vet.

Signs of bladder stones can sometimes be difficult to detect, but it is usually associated with:

  • Urinary tract infection
  • Frequent urination
  • Straining on urination
  • Blood in the urine
  • Increased water consumption
  • Listlessness
  • Poor appetite

An experienced vet may be able to remove the stones; this is accompanied by appropriate antibiotic therapy.

Dietary management to help dissolve the urinary stones and prevent their recurrence is not practical with hamsters.

Hamsters: antibiotic sensitivity

Hamsters as a group are unusually sensitive to the potentially lethal effects of certain antibiotics, whether they are given orally or by injection. Potentially harmful antibiotics include ampicillin, penicillin, erythromycin, lincomycin and streptomycin.

The major way in which certain antibiotics cause reactions is by altering the normal microbial balance within the gastrointestinal tract. Once the normal intestinal microfloral balance has been upset, certain bacteria multiply to abnormally large numbers.

The multiplying bacteria produce harmful chemicals that can have lethal effects. Certain antibiotics are directly toxic and do not alter the normal microbial balance within the gastrointestinal tract; these antibiotics should never be used in hamsters.

Though injectable antibiotics can cause the problems described above, oral antibiotics are more often associated with them. Antibiotics should never be given to hamsters unless they are prescribed by your vet.

If your hamster is prescribed either oral or injectable antibiotics, try feeding it 1/2 cc (1/10 teaspoon) of plain, white yogurt orally morning and evening for the duration of the antibiotic treatment, and for an additional 5-7 days following treatment.

Yogurt helps replace those beneficial intestinal bacteria that often perish during antibiotic treatment.

Hamsters details

Hamsters are small, virtually tailless, velvet-furred rodents with enormous cheek pouches. They originated in the Middle East and south eastern Europe. The most common and popular breeds, both as pets and laboratory animals, is the golden or Syrian hamster.

Color and hair-type varieties of the golden hamster include cinnamon, cream, white, and “teddy bear” (the long-haired variety). Most of the hamsters sold as pets or used in research are the descendants of 3 litter mates domesticated in 1930.

  • Scientific name: Mesocricetus auratus.
  • Potential life span: 2-3 years.
  • Adult body weight: 100-150 grams (adult females are slightly larger than adult males).
  • Desirable environmental temperature range: 18-24°C/65-75°F.
  • Desirable relative humidity range: 30-70%.
  • Recommended age at 1st breeding: male: 10-14 weeks; female: 6-10 weeks.
  • Length of oestrous (heat) cycle: 94 hours.
  • Gestation (pregnancy) period: 15.5-16 days.
  • Average litter size: 5-10 young.
  • Age at weaning: 3 weeks.

The cheek pouches are a relatively unique anatomic feature of hamsters. They are actually a cavernous outpouching of the oral (mouth) cavity on both sides, extending alongside the head and neck to the shoulders. These pouches are used to store food and allow the hamster to transport food from where it is gathered to the hamster’s den or nest. The food is then eaten later, at the hamster’s leisure.

Hamster owners not familiar with these cheek pouches often panic when seeing them fully distended for the first time, thinking they represent tumours or abscesses. Another relatively unique anatomic feature of hamsters is the paired glands in the skin over the flanks. These appear as dark spots within the hair coat and are much more obvious in males than females. These glands are used to mark a hamster’s territory and also have a role in sexual behaviour.

Hamsters are very popular pets today because of their availability, affordability, small size, cuddly appearance, often docile temperament and relatively clean habits. They are not very long-lived, which can be disconcerting to owners, especially children.

Many parents, however, believe that having their children experience the relatively short period of companionship and subsequent death is a meaningful way to expose children to the “ups and downs” of life. For many years hamsters have been used in biomedical research laboratories. Consequently, their medical problems have been traditionally approached on a group basis, rather than on an individual basis.

As a result, very little practical information exists on the medical care of individual hamsters.