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General Pet Rodent Care Sheet

| Introduction | Classification | Biology | Buying & Choosing | Stages | Sexing | Handling & Transporting | Rodent Bite | Keeping & Breeding | Food Related Problems | Behaviour | Environment Enrichment | Potential Health Problems | Books | Related Topics | References & Further Reading | Related Websites |
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Small Rodent Introduction:

Members of the order Rodentia (ro-den'che-ah), or otherwise known as rodents, include rats, mice (singular = mouse), hamsters, chinchillas, mastomyx, gerbils, squirrels, beavers, porcupines, chipmunks, woodchucks and lemmings. This order makes up the largest mammalian order and is characterized by animals having upper and lower jaws with a single pair of continuously growing incisors.

The word rodent originates from the Latin words rodere, meaning to gnaw and dens or dentis meaning tooth. Although rabbits and hares have similarities in their teeth configuration they are actually grouped in the order Lagomorpha (lag"o-mor'fah). Rodents are found in vast numbers on all continents except Antartica, most islands and most habitats. Their success is probably due to their small size, short breeding cycle and the ability to gnaw, eat and survive on a wide variety of foods.

This care sheet will mainly cover small pet rodents such as rats, mice, hamsters, gerbils and mastomyx

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Small Rodent Classification:

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Small Rodent Biology:

Zoology
The Class Mammalia (mah-ma'le-ah) consists of a very diverse group of animals all of which poses hair, mammary glands, specialized teeth, a diaphragm, three-middle-ear ossicles, sweat-, sebaceous- and scent glands, a four chambered heart and a large cerebral cortex. The infraclass Eutheria (u-ther'-e-ah) includes all the mammals with complex plancentas or the so-called "placentals". Rodents are the largest order of mammals and have single pairs of ever-growing incisors. It is important to note that rabbits do not belong to this order, but to the order Lagamorpha.

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Buying & Choosing A Small Pet Rodent:

Pet rodents are available from most pet shops and private large or small scale breeders. Some experimentation facilities might also be generous enough to sell (genetically pure) rodents. Try not to purchase any live stock from facilities which house rodents in overcrowded, stinking or dirty cages. To prevent disappointment, avoid purchasing live stock over long distances and/or when the original animals were not inspected first.

Only buy young, healthy, alert, well fleshed rodents. Avoid rodents with a hunched up- or any abnormal  posture, bite marks, lumps, hairless patches, ocular or nasal discharges or movement abnormalities.

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Small Rodent Life-Stages:

Small rodents can be divided into four life-stages according to their age and size. These stages are pinkies, fuzzies, hoppers or jumpers and adults. Pinkies or pinks (day one to about day seven) are new-borns that are still hairless. Fuzzies (day seven to about day 21) are in their fuzzy hair stage until they open their eyes. Hoppers or jumpers (about three weeks) are weaned offspring. In every stage adult males (bucks) are usually a bit larger than the females (does).

The young of some small rodents, like the Multimammate mouse, are born with some degree of hair.

 Figure 1  The different stages of mice. a Adult doe in late pregnancy; b Adult doe with pups; c Adult doe with fuzzies; d Adult buck with hoppers.

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Small Rodent Sexing:

To determine the gender of small rodents, they should be roughly divided into one of the following age groups:

• Before three weeks of age
• After three weeks of age, but before sexual maturity
• After sexual maturity

Sexual maturity or puberty is where the animals are ready to mate and conceive viable offspring. This is usually from about six weeks after birth. Rat breeders believe that juvenile rats can be sexually mature from the age of five weeks. To prevent (in)breeding by siblings, small rodents should be separated from these ages.

It should be noted that for female adulthood or the breeding age are not the same as sexual maturity. In both these time frames small rodents are able to reproduce successfully, but from a reproductive point of view adulthood is weight dependant and not age dependant. I most production systems females should only be incorporated into breeding systems when they have reached about 80 percent or more of their expected adult mass.

Before three weeks of age
The best time to sex this age group is about two to three weeks after birth. This is at about the end of the fuzzy stage, just before, to just after the young opens their eyes. Females will display nipples on their ventral side through their fur where males will not. When examining animals too late in this group the fur will have grown over the nipples, making it easy to confuse males for females.

After three weeks of age, but before sexual maturity
At this point males and females appear almost identical. As mentioned above, no nipples will be visible on females and males have not yet developed prominent external genitalia (a penis and two testicles). Sexes can be identified by comparing two different sexes with each other. Both sexes will appear to have a penis, but males will have a greater distance between the penis (the real penis) and the anus (situated just ventral to / below the tail). In males this space will be about double the distance when compared to females. In females the "penis-like" organ is called the external urethral opening through which urine is excreted.

After sexual maturity
After sexual maturity both sexes will have fully developed external genitalia. Males have visible testicles with a distinct penis, and females have a pink vulvar opening without testicles ventral to the anus. The vulva becomes more pink to reddish when the animal is in oestrous (the time when a female will allow biological breeding).

 Figure 2  The external genitalia of a male rat, male- &  female mouse. a Adult male rat (buck). Note the penis & the large visible testicles; b Adult female mouse (doe). Note the similarity between the external urethral opening & the penis in bucks. The distance between the anus, situated just ventral to / below the tail & the urethral opening is significantly smaller than those in bucks. Teats might also be slightly visible in light coloured fur; c Adult male mouse; note the penis & the visible testicles.

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Small Rodent Handling & Transporting:

Larger rodents like tame rats and mastomyx can be picked up and handled without effort, while hamsters and mice which are somewhat smaller, can easily be injured. Never handle wild rodents without protective hand gear. Rats, mice and mastomyx can be picked up by their tails. Grip the tail as near the base as possible and support the body of the animal with the other hand by letting it stand on the handler's palm. It is not always necessary to constrain tame rodents, but if the animal is nervous keep hold of its tail. Never hold a rodent around its body and never let small children or irresponsible people handle these animals. Do not handle more than one rodent at a time as they might be too much to handle.

Rodents can get tame enough to be allowed to walk and climb all over the owner. Remember that even tame animals must be handled with caution. Never put a tame rodent on the ground without constant and close observation. Tame rats and mice will happily sit on their owner's shoulder, in an open pocket or underneath loose clothing if you let them.

To prevent the transmission of potential diseases from rodents to humans, a handler should always wash his / her hands and arms with a proper disinfectant soap after contact with these animals or their caging.

Small rodents can be temporary transported over short distances in small paper boxes or paper bags or for  longer periods in plastic containers such as so called "Pal Pens". Ensure that there is enough effective ventilation holes in whichever medium is used. Never transport rodents without a secure container near by.

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Small Rodent Bite:

When for some or other reason a handler gets bitten by a small rodent, tame or wild, it is recommended to consult a qualified medical doctor immediately for advice. In the meantime bleeding bite wounds can be managed by letting it keep on bleeding (i.e. do not try to stop the bleeding initially) and by holding the wound under running tap water for a few minutes. This will help to flush most of the introduced bacteria from the wound. After copious flushing the wound can be covered or pressurized to stop the bleeding. A registered disinfecting agent such as Dettol™ or similar products can be applied topically. Inoculation with a human tettanus vaccination might be warranted.

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Keeping & Breeding Small Rodents:

Note:

Although healthy rodent individuals are generally clean, their cages can smell bad very easily. Males tend to stink more than females. The only way to overcome stinking problems and prevent discomforts and potential diseases to the animal and keeper is by regular cage cleaning and by preventing overcrowding. Cage substrate should be changed once to three times a week (depending on the number of animals per cage and on the type and size of the cage) and  should be washed and disinfected at least once month.

Most domesticated rodents make good pets, but they are short lived animals. The average age of rats is about four years and those of mice are three.

The bare minimum for keeping small rodents:

• Wire cage, plastic container, glass tanks
• Open space
• Food & water
• Bedding
• Shallow container for food
• Shallow container for water
• Keeping and/or breeding stock

Cages & Containers

Although single rodent can live comfortably in relative small areas, cages should be as big as possible. Recommended minimum sizes are dependant on the amount of animals housed together and the species of rodent. Rats need larger cages than mice. Overcrowded cages accumulates more waste products (urine and faeces) and will smell bad and start to accumulate potential disease causing bacteria faster. A rough guideline would be to keep four or less adult mice in a confined space of 35 x 25 x 13 cm / 14 x 10 x 5 ".

Basically any secure cage or container can be used to house pet rodents. An old glass or fish tank with a well ventilated lid is ideal for most pet rodents. Specific rodent housing such as "Pal Pens™" and hamster or mouse mesh/wire cages are ideal. Some self made wooden or plastic containers are also in use. Self-made cages should be chew- and escape proof, have proper ventilation, be non-absorbable and have non-abrasive surfaces for effective disinfection and cleaning. Items such as  paper or wooden shoe boxes, thin wooden cages or anything similar should be avoided as permanent housing.

Cages and containers need as much ventilation as possible. Proper ventilation decreases the build-up of waste products and microbial pathogens which ultimately reduces the risk for respiratory problems and lung infections.

Most pet rodents are nocturnal (night living) animals, but in captivity they can be active during night and/or day. Never put a cage in direct sunlight or in front of an open window. Apart from the fact that sunlight might increase the temperature to lethal levels, not all rodents  like sunlight and might feel threatened by it. See-through plastic- or glass type containers will heat up very quickly (even if it is well ventilated) and can cause cruel mortalities.

 Figure 3  Different types of housing for rodents. a & b Smaller & larger acrylic containers, also called Dessert dens™ or Pal pens™; c Glass tank with a lid; d Hamster mesh cage; e Mouse mesh cages (35 x 25 x 13 cm / 14 x 10 x 5 ") are ideal for commercial mouse breeding; f Mouse mesh cage plastic bottom; g Self made container with a mesh roof & a modification for a waterer; h Mouse mesh cage bottom fixed with Pratly Putty™.

Cage Maintenance
Pratly Putty™ can be used to fill chewed holes in plastic bottoms of commercial hamster and mouse cages (Fig. 3h). Instead of replacing worn down or chewed mesh cages it can be restored with a thick/double layer of non-toxic (lead free) spray paint.

Temperature
Room temperatures (24 ºC / 75 ºF) are warm enough for most pet rodents. wild rodents are very adaptable in various temperature ranges, but unlike captive rodents they can move in and out of desired areas. Some genetic / laboratory rat and mouse strains might have different temperature requirements. High producing strains will need constant day and night temperatures throughout the year. Abrupt and large temperature fluctuations will induce stress, reduced growth, cause poor reproduction and may ultimately lead to increased mortalities amongst the adults and new-borns.

During cold winters or cold spells additional external heat sources should be used to increase temperatures. Commercial heat pads or heat strips available from most pet shops can be placed beneath, on the outside of individual containers. Under-cage heating should never cover more than about a third of the floor area of the cage or container. Standard heating equipment such as electrical- or gas heaters, heating fans or heated air conditioning can also be used to keep the temperature of entire room at a desired level. Make sure to provide adequate cage ventilation and supply ad lib water when using any for of additional heating.

It is also important to supply good quality ad lib food during colder temperatures. Wet and cold environments might be enough to starve a small rodent to death within one night.

Food & Water
Fresh potable water and and high quality food should be available on a constant basis (ad libitum).

In cage water dishes get easily contaminated with bedding and should be cleaned and refilled daily. Because small individuals can drown in large/deep water bowls they should also be avoided if possible. When water dishes are used they should be raised from the floor by using a secure base. Other practical ways to supply water to rodents is by using external waterers like self made water bottles or commercial mouse drinkers. Water containers should be cleaned and disinfected at least every second day.

 Figure 4  Rodent drinkers / waterers. 1 & 2 Commercially available rodent drinkers for wire cages; 3 & 4 Self made coffee bottle drinkers. 1 to 2 mm holes is drilled in the lids of these bottles & placed upside down with water. It is used on mesh cages & works especially well on mouse mesh cages. Make sure the animals, both large and small, can reach the underside of the bottle easily when used; 5 Bottle cleaner - useful to clean out algae from coffee bottle drinkers; 6 Bulk waterers also work well in larger containers when it can be kept clean. Make sure these waterers are not to deep for youngsters to drown.

Hamster or rodent food can be bought commercially from almost any pet shop or large store selling pet goodies. Self made food mixtures containing sunflower seed, rabbit pellets, peanuts with or without shells, wheat, dog food and whole corn/maize can also be offered. The proportion of sunflower seed, rabbit pellets and peanuts should be on the lower side as they are likely to provoke skin irritations when used for long periods. In South Africa commercial mouse cubes are produced by Epol® and are distributed as 50 kg bags through some co-ops.

Rodent vitamin and mineral supplements are available from specialized vets or pet shops. Refer to the instructions or ask the seller to prevent incorrect levels of supplementation. Fresh fruit and vegetables can also be offered in small amounts as extra supplementation.

Pet rodents can be spoiled with treats such as dog biscuits or specific rodent snacks.

 Figure 5  a & b Commercial Epol® mouse cubes; c Wood shavings.

Cleaning, Bedding & Disinfecting
The bedding or substrate is the layer that covers the floor space of the cage. One layer of wood shavings is more than enough for small rodent bedding. This will aid in the absorption of urine / moisture, potential malodorous smells and is used by rodents for nest making. Pine shavings, finer wood shavings and sawdust may increase the incidence of eye and nose irritation and subsequent respiratory problems. Wood shavings should also be dust free and free from any dangerous preservatives and insecticides. Wood shavings are commercially available from most pet shops and in bulk from some woodwork factories. Scented wood shavings are also available from some retailers. Ripped or shredded pieces of newspaper, pieces of sponge and toilet paper can be added as optional environment enrichment and will eagerly be used for nesting.

The cage should be cleaned once to three times a week depending on the number of animals per cage and the size and type of the cage. Bedding should always be fresh and dry. Cage should be washed every time the bedding is replaced and disinfected at least once every two months.

Strong undiluted disinfectants may cause respiratory problems, skin problems and may even kill rodents and their young. Appropriate diluted chloride solutions like Milton™ or Jik™ or other disinfectants like F10™ Veterinary Products are proven to be safe and effective. Make sure to follow the instructions mentioned on the label of whatever product is used. Rinse excess solution off with clean running tap water after each disinfection, dry excess water and let it sun dry for at least twenty minutes before re-use. Cages can be cleaned and disinfected in the presence of pups and kittns. Adults and babies can be manualy carried over to a clean cage with bedding while the dirty cage is being cleaned.

While with some pet rodents like mice, the babies can be separated from the mother for up to a day, the cleaning of cages while there are babies can potentially result in some degree of rejection and cannibalism by the mother, other females, other males or the father.  In spite of good success rates it is better to handle the young as little as possible and to clean cages only when necessary.

Hamsters on the other hand will almost always kill and eat their babies after human handling. If absolutely necessary use clean gloves or toilet paper to prevent direct contact and "human contamination" of babies. It is also interesting to mention that we have seen nursing mouse does raising dwarf hamster babies and multimammate mice kittns.

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Food Related Problems:

Undernutrition and nutritional deficiencies can rarely be seen when low quality, self-mixed or non-commercial mixtures are fed. The two groups that are theoretically most affected are the post-weaned growers and the pregnant and fostering females. Typical signs of poor nutrition includes a ruffled, unkept haircoat, an Apart from being in a poor overall body condition, signs of deficiencies include abnormal mortalities, apparent cannibalism and unnoticed cannibalism, i.e. lower numbers of surviving pups and kittns and an overall reduced number of offspring born per pregnant female. Both males and females might also take longer to reach puberty or if a male is severely affected a whole group of females might fail to produce offspring. All these signs will most often disappear very soon after a good quality food is introduced.

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Small Rodent Behaviour:

Aggressiveness
Generally rats tend to fight less among each other than mice, even after the introduction of new cage mates. Rodents should as a rule never fight amongst each other, not even amongst the same gender. This is usually not the case when they are not raised together. Aggressiveness is an unfavorable characteristic in pet rodents should be a criteria for selection. Although mice are naturally more aggressive, the above rule should still be kept in mind. By not breeding with aggressive animals the incidence of behaviour will gradually reduce in a breeding population or program.

The following situations can cause more than normal fighting among each other and aggressiveness towards the keeper:

• More than two dominant sexual mature males in the same container
• Newly introduced males and/or females into an established group
• Females with babies
• Hungry, under- or unfed animals

Fights among the same gender are common, especially among males and in smaller cages or containers. Males usually fight for dominance over their "territory". Note the difference between aggressive fighting and young animals playing amongst each other or males trying to mate with females. Females can get very aggressive towards new arrivals when they are nursing their young.

No pet rodent should attack a human, even if they are under stress or have babies. Males and females should also not eat or kill their babies under normal circumstances (excluding handling, cage cleaning, transporting, underfeeding or anything else that may cause stress). Aggressive and biting animals should not be used as breeding stock.

Hungry, unfed animals might confuse a finger with a nice piece of meat. Parents might also kill and eat their babies for the same reason. The incidence of biting amongst each other, cannibalism and aggressiveness towards the owner might increase by feeding meat and/or fresh blood containing products.

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Small Rodent Environment Enrichment:

In the context of pet rodent keeping, environment enrichment refers to the provision of environmental aspects which makes it more stress free and more naturalistic. In short it should make the rodent feel more "at home"  by giving it more stimulation and simulating a bit of its natural habits.

Various rodent toys like cages with tunnel systems, various nesting toys and exercise- or running wheels are commercially available from most pets shops. Parrot and human baby toys are also favourites and are available at pet shops and toy stores. Home made items like normal clean toilet paper, ripped newspaper, toilet paper rolls, pieces of sponge, smallish pieces of wood, leathers, balls, ropes and marbles can also be added as environmental enrichment. These items will most probably end up as nesting structures, but at least they served their purpose.

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Potential Health Problems Of Small Rodents:

Rodents are prone to some mite infestations. The Tropical rat mite (Ornithonyssus bacoti) infests rats. Engorged mites can be seen as little red organisms on various areas of the animals. They are blood sucking and may cause blood loss and when in large enough numbers they can also cause anaemia. On direct contact they might infect and cause temporary irritation to humans.

 Figure 7  A mouse with a huge growth in its left axilllary area. This can be a cancerous growth or an abscess secondary to a bite wound from a cage mate.

Other health related issues include trauma leading to the loss of body parts and primary and secondary haematomas, abscesses, cancerous growths, heart failure and respiratory tract infections.

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Small Rodent Books:

Buy Books from Kalahari.net

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"If you think I should add more information to this section, think that something is incorrect or you have any additional information regarding keeping of pet rodents, use the form below or go to our contact page to get in touch. I would love to hear your ideas or methods you might use that is different than ours."

Last updated 12 July 2008 by Renier Delport

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"Always remember only to buy healthy animals from reputable pet shops and breeders. Make sure to buy animals that are captive bred in your own country and that it is not illegally imported or caught from the wild.

If you've read something funny, or heard something that sounds out of place, use your common sense before applying. It is extremely important to do research from more than one source (before buying or accepting a new animal). Browse other internet pages, read related magazines and talk to experienced people."

Small Rodent Related Topics:

Other Care Sheets

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Small Rodent References & Further Reading:

Fox, S. 2003 The Guide To Owning A Mouse, T.F.H. Publications, Inc.

Alderton, D. 2001 The Ultimate Encyclopedia of Small Pets & Petcare, Lorenz Books.

Miller, S. A. & Harley, J. B. 1999 Zoology, Fourth Edition, McGraw-Hill.

The Diagram Group, Pets: Every Owner's Encyclopedia, Paddingston Press LTD.

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| Introduction | Classification | Biology | Buying & Choosing | Stages | Sexing | Handling & Transporting | Rodent Bite | Keeping & Breeding | Food Related Problems | Behaviour | Environment Enrichment | Potential Health Problems | Books | Related Topics | References & Further Reading | Related Websites |
| Email This Page |

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