Other species of hamster occasionally used in research
include the
- Chinese hamster (Cricetulus
griseus)- occasionally used in research
- European hamster (Cricetus
cricetus)
- Armenian hamster (Cricetulus
migratorius)
- Dzungarian or dwarf hamster (Phodopus
sungorus)
The History of Hamsters in Research:
The Syrian or golden
hamster is native to the deserts of the Middle East. A litter of
three hamsters were captured in Syria in 1930, and the first hamsters
were imported into the United States in 1938.
The Role of Hamsters
in Research:
Hamsters were the fifth
most commonly used animal in research in 1999 (after mice, rats, rabbits
and guinea pigs). They are important animal models for research in
immunology because they lack white blood cells, resulting immunologic tolerance and allows transplantation of tumors. They have
been used to study a
number of infectious diseases of humans and animals, diabetes mellitus,
dental caries, muscular dystrophy and cardiac disease.
Hamster Statistics:
| Criterion |
Syrian Hamster |
| Life span |
1.5 - 2 years |
| Adult size |
90 - 150 gm |
| Temperature |
101 - 103 °
F |
| Pulse |
250 - 500 bpm |
| Respirations |
35 - 135 rpm |
| Estrous Cycle |
4 - 5 days |
| Gestation |
15 - 18 days |
| Weaning Age |
20 - 25 days |
The Anatomy and Physiology of Hamsters:
As small rodents,
hamsters have many similarities to rats and mice. They also have
several species-specific characteristics. The hamster is stouter than
rats or mice, with a short haired tail. Wild hamsters are
reddish-brown dorsally and white ventrally.
Hamsters are hindgut-fermenting monogastric
herbivores. Like the rat and mouse, they have open-rooted
incisors which may become overgrown, resulting in malocclusion.
The hamster incisors are fully erupted at birth (ouch!!).
The hamster has large
cheek pouches that are thin-walled and highly distensible. They extend
far back, allowing the hamster to store and transport
large amounts of food. The cheek pouches are considered immunologically
privileged sites, and tumors can be transplanted into them without
rejection.
Hamsters have sebaceous
glands on their hips (flanks) that produce pheromones used for sexual
activity and territory marking. These glands are darker colored
than the surrounding fur and more prominent in male hamsters.
Hamster Reproduction:
Female hamsters are
larger than the males and has a more pointed caudal end than the
male. The male's large scrotum give his caudal end a more rounded
appearance.
Female hamsters are
seasonally polyestrous and spontaneous ovulators. Fertility
decreases in the winter months, even under artificial lighting with a
12/12 photoperiod. Mammary glands are present only on female
hamsters. A copulatory plug may be detected after mating.
Females are receptive to
breeding (in estrus) for a few hours of their estrous cycle. If she is
disinterested, she may attack and even kill the male. After a
short gestation of 15-18 days, altricial young are born. The
female may abandon or cannibalize her offspring during the first
pregnancy and during the first week postpartum. Be very careful
not to disturb her during this time!
A variety of mating
systems can be used, but because of the high incidence of fighting,
mating can be difficult. A monogamous system may be effective.
The harem system can also be used, with the females
removed from the harem cage several days after mating and individually
housed until the offspring are weaned. It is advisable to watch
the hamsters closely when they are first paired to ensure that mating
and not fighting activity is occurring.
Hamster Temperament:
Hamsters tend to be
suspicious of people and are unpredictable and occasionally aggressive,
making them more difficult to handle than other rodents.
Technical Procedures:
Hamsters can be hand
tamed, although some remain a challenge to
work with. Hamsters can be moved by scooping them into your cupped
hands. To restrain them for technical procedures, it is important
when scruffing them to grasp as much loose skin as possible
Blood can be collected
from many of the same sites used in rats and mice, including the
retro-orbital venous plexus, saphenous vein and cardiac puncture.
Hamster Husbandry:
Hamsters are nocturnal
rodents. They enjoy exercise wheels and frequently use them at
night. They also burrow, chew and escape whenever possible.
The optimal temperature
for hamsters is 65 - 70°
F. If the temperature drops below 55°
F, hamsters may gather food and enter a deep sleep. They are
permissive hibernators; they do not lay down fat prior to sleeping
and are readily roused if the temperature increases to their preferred
range.
Hamsters can be housed in
small compatible groups or singly. Enrichment with exercise wheels,
bedding for burrowing activity and clean branches for chewing all
improve the welfare of hamsters.
Hamsters have a blunt nose and may have difficulty eating
from a slotted cage top. They are also, however, hoard feeders,
and may hide food from a dish, making it difficult to judge
food consumption.
|Hamster Health and
Disease:
Care must be taken when
using oral penicillin-type antibiotics in hamsters. Their gastrointestinal flora may be adversely affected, leading to diarrhea and death.
Sendai viral infection, Tyzzer's disease and
salmonellosis can occur in hamsters, producing diseases similar to that
of rats and mice.
A relatively common and
important disease of hamsters is proliferative ileitis or
"wet tail." There are a number of bacteria associated with the disease, and stressful stimuli, such as transport,
overcrowding, experimental procedures and diet changes, are contributing
factors. The result is a severe diarrhea and is primarily seen in
newly weaned hamsters.
Lymphocytic
choriomeningitis (LCM) is a viral zoonosis that, for a time during the
1970s, resulted in the removal of hamsters from the pet
trade.
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