UNIT 13
Lab Animal – Rodent, Rabbit Health Management
Part I – Background Information on Rabbits and Rodents
Background information on rodents
Mouse

The most popular animal used in research. Approximately 10 million are used
annually in the U.S. for such research as drug testing, aging, virology, congenital
defects, neoplasia, genetics, and autoimmune disease to name a few.

Mice live two to three years and are classified either ecologically or genetically. The
ecology group is subdivided into axenics, gnotobiotes, specific pathogen free, and
conventional. Genetically mice are classified as random-bred, inbred, or F1 hybrids.

There are over 100 strains of mice in existence today. The long established SwissAlbino mouse is probably the source of most mouse strains. Some examples of
popular inbred strains are the C3H mouse and the C57BL/6. The Swiss-Webster and
the ICR are good examples of outbred mice.

Mice become sexually mature at approximately two months. They breed for
approximately 7 to 18 months and produce 6 – 8 litters consisting of 10 – 12 pups per
litter. The pups are weaned between 21 – 28 days.

Mice are fed ad libitum. They adapt well to either water bottles or automatic
watering systems. A good maintenance diet contains 4 to 5 % fat and 14 % protein.
These percentages should be raised 1 –2 points for animals that are in the growth and
reproduction mode. An adult mouse will eat approximately 15 grams and drink 15 ml
of water per 100 grams of body weight per day.

Mice have a highly developed sense of hearing. High-pitched sounds, for instance
from a computer, may cause audiogenic seizures in some strains and possible
destruction of litters.
Rat

Rats are well-defined animals that make excellent research animals ( 4 million used
annually) as well as pets. They are classified in the same manner as mice –
ecologically and genetically.


The laboratory rat, Rattus Norvegicus, is a rodent of the family Muridae. Wild rats
are colonial nature and active burrowers. Laboratory rats do maintain some of the
burrowing behaviors.
There are different strains of rats. Some examples are Sprague-Dawley, Wistar,
Fischer, Brattleboro, and the Long-Evans. Rats are like mice in that there are inbred
and outbreds. Some of the more popular inbred strains are the Fischer 344, Wistar,
and the SHR (Spontaneously Hypertensive Rat). Outbreds include the SpragueDawley and the Long-Evans.

Rats are known to live beyond three years. The breeding age for rats varies from 65
to 110 days. The gestation period is 21 days and they normally deliver anywhere
from 6 to 12 pups.

Rats are neophobic (cautious eaters) and nocturnal (feed at night). They are fed ad
libitum and will consume 5 grams of feed and 10 ml of water per 100 grams of body
weight. Commercial diets for rats should contain 17 % protein and 4.5 % fat. As in
the case of mice this should be increased during periods of growth and reproduction.

Rats like horse lack a gallbladder and are unable to regurgitate.
Guinea Pig

The Guinea Pig, Cavia porcellus, is a popular pet that has its roots in the Andes
Mountains of South America. This animal is known for its messiness, need for
supplemental vitamin C, tendency to stampede, and fastidious eating habits.

The Guinea Pig can live up to 8 years, however, in most home environments they live
not more than 5. Guinea Pigs are classified as hystricomorphs or hedge-hog like
animals.

There are three major strains of the Guinea Pig. The English, widely used in
research, the Abyssinian, and the Peruvian. The latter are quite popular for show as
well as 4 – H projects.

Guinea Pigs are weaned at approximately 18 – 24 days and reach sexual maturity at
around 12 weeks of age. Their breeding life lasts anywhere from 18 months to 4
years. They have one of the longer gestation periods, approximately 65 days, and
give birth to 2 – 4 piglets.

Guinea Pigs are herbivores and like horses and rabbits are cecal fermenters. Due to a
lack of an enzyme they are share a common bond with non-human primates as well as
humans in that they need supplementary Vitamin C in their diet. Guinea pigs
consume 6 grams of feed and 10 – 40 mls of water per 100 grams of body weight
daily. The diet should contain 18 – 20 % protein and 10 – 16 % fiber.
Hamster
Hamsters, popular in research and as a pet, are known for their hardiness, periodic
pugnaciousness, ease of taming, and ability to escape their confinement.
There are approximately 370,000 hamsters used in research annually within the U.S.
Hamsters are characterized by short life spans living in most cases only 18 – 24 months.
There are three strains of hamsters that one should be familiar with – Golden Syrian, the
Siberian, and the Chinese hamster. The Golden Syrian is the most frequently used strain
in research, but the Chinese hamster provides a good model for Type 1 juvenile-onset
diabetes.
Hamsters have the shortest gestation period of the rodent family at 15 – 18 days. They
normally mature sexually at 32 – 42 days and have a breeding life span of one year.
Litters usually average 5 – 10 young.
Hamsters are granivorous (i.e. they will eat insects). They are normally fed a commercial
pelleted diet that contains approximately 16 % protein and 4 – 5 % fat. Hamsters are
coprophagous and routinely carry out this practice 20 times daily. Hamsters eat 8 – 12
grams of feed and 10 mls of water per 100 grams of body weight.
An interesting fact about hamsters is that they are known to conduct what is called a
pseudohibernation. If environmental conditions are present, shortened day length and
lowered room temperatures, they will gather food and go into a sleep pattern for extended
periods of time.
Gerbil

The common gerbil, Mongolian, is an active, nearly odorless, and normally nonaggressive animal of the rodent family. The Gerbil originated in the desert regions of
northern China. They average three years for a life span.

The Mongolian gerbil is by far the most widely used gerbil in research in the U.S.
Depending upon taxonomist 11 to 15 other species of gerbils are in existance and
several of these are more popular for use in research in other countries.

Gerbils reach sexual maturity at about 10 – 12 weeks and average 15 – 20 months for
breeding life. The gestation period is 24 – 25 days and usually 4 –5 animals are born
each time. Gerbils are characterized as among those animals which mate for life.

Gerbils are classified as both herbivorous and gravnivorous. They are fed ad libitum
and owners should be warned to be cautious with the use of treats. A pelleted chow
containing 16 – 22 % protein is adequate. They normally consume 5 – 8 grams of
feed daily and their water intake is rather low at 4 mls daily. This is not surprising
since they are a desert animal.

An interesting behavior of gerbils is that they occasionally exhibit epileptic seizures
lasting usually less than a minute.
Rabbit

The domestic rabbit, Oryctolagus cuniculus, is a lagomorph of the family Leporidae.
There are over 20 breeds of rabbits as classified by the American Rabbit Breeders
Association. Classification is based on size ranging from the large breeds (Flemish
Giant), to the medium size breeds (Californian), and the smaller breeds of which the
Dutch belted is a good example.

Rabbits reach sexual maturity at approximately 6 – 9 months. Their breeding life
extends out to three years and they are capable of producing anywhere from 7 to 25
litters of 7 – 8 kits per litter.

Rabbits are monogastric, hindgut fermenters that practice cecotrophy. Adults
consume approximately 130 grams of feed a day and drink 150 mls of water although
consumption can increase to 900 mls for a lactating doe. The diet should contain 12 –
19 % protein, 2 % fat, and 16 – 25 %. A high fiber diet should be given to prevent
obesity, hair chewing, and enteritis.
Part II - Rodent and Rabbit Management Practices
Public Health Concerns
Mouse: Salmonellosis and lymphocytic choriomeningitis are two zoonotic diseases that
occur in mice, however, their occurrence is rare. Allergies to fur dander is a growing
problem today among animal care technicians and pet owners.
Rat: Some of the zoonotic diseases carried by the rat are leptospirosis, streptococcal
infections, salmonellosis, cestodiasis, hemorrahgic fever with renal failure, and rat bite
fever. These diseases are common in wild rats but would be rare in domestic laboratory
rats.
Guinea pig: Diseases of public health concern would be rare in the guinea pig. They
may carry bacteria such as Bordetella, Salmonella, Yersinia, and Streptococcus but cases
of transmitting this to human beings is extremely rare.
Hamster: An outbreak of Lymphocytic choriomeningitisu (LCM) was recorded in
humans in 1974 –75. But severe cases of this disease associated with guinea pigs is rare.
Salmonellosis is a potential zoonotic disease but the risk of exposure is small. Rabies is
also highly unlikely.
Gerbil: Gerbils in domestic and research settings have very few disease problems. They
have potential to carry Salmonella and Hymenolepsis but the potential to pass this on to
humans is extremely small.
Rabbit: Diseases of the domestic rabbit that have public concern are salmonellosis,
tularemia, rabies, ringworm, tuberculosis, and toxoplasmosis. Risk to the public is as in
the case of rodents small.