Rodent Biology
Last modified
on
May 26, 2010
Rodents (Order Rodentia) can be grouped into three
suborders: Myomorpha (Family Muridae and Cricetidae), Sciuromorpha (squirrels
and woodchucks), and Hystricomorpha (Family Cavidae, Chinchillidae, and
Octodontidae).
They all have four hypsodont incisor
teeth.
Molars sometimes have roots that
cease growing in myomorphs, whereas in hystricomorphs the molars continue to
grow for life.
Myomorphs have a stomach divided
into a cardiac portion lined with stratified squamous epithelium and a
glandular pyloric portion, or fundus. The dividing line is called the limiting
ridge.
Myomorphs have several litters per
year, unlike sciuromorphs that have one litter annually. Since several species
have fertile postpartum estrous periods, they are prolific. Myomorphs and
sciuromorphs are born hairless and helpless (altricial), and their dams build nests for
them; but hystricomorphs are precocious.
See below for a table of
normative data on several non-traditional rodents. For a summary of
cryopreservation of murine reproductive cells, click
here.
Housing and husbandry of rodents is
located in the Resource Management section on the rodent
husbandry page. A table of trivia that often appears on the exam is here.
| Selected Normative Data |
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| (from Laboratory Animal Medicine; Fox, J.G., Cohen, B.J., Loew, F.M., editors, c. 1984 Academic Press, page 192) |
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Chinchilla |
Gray squirrel |
Cotton rat |
White-tailed rat |
Woodchuck |
Gerbil |
White-footed mouse (P. leucopus) |
Deer mouse (P. maniculatus) |
Meadow vole |
Multimammate rat |
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| Adult weight, gm |
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| Male |
400-500 |
400-700 |
70-200 |
85 |
3-7 kg |
60 |
22 |
19-21 |
40-60 |
40-45 |
| Female |
400-600 |
400-700 |
70-200 |
130 |
3-7 kg |
50-55 |
22 |
19-21 |
40-60 |
40-45 |
| Life Span |
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| Usual |
10 Y |
14-15 Y |
23 M |
2.4Y |
5-6 Y |
3Y |
2-3Y |
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33 W |
2-3 Y |
| Maximum |
20 Y |
20 Y |
3 Y |
3.2 Y |
15 Y |
5 Y |
38 M |
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124W |
38 M |
| Water consumption |
- |
- |
- |
5 ml |
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4-7ml/100gm |
- |
- |
- |
- |
| Food consumption |
- |
50 gm |
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- |
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5-8gm/100gm |
- |
- |
7-10gm |
6 gm |
| Chromosome No. |
64 |
40 |
- |
32 |
- |
44 |
- |
48 |
46 |
36 |
| Body temperature (C) |
36.1-37.8 |
- |
- |
- |
- |
38.2 |
- |
- |
- |
- |
| Heart rate (beats/min) |
100 |
390 |
- |
- |
180-264 |
360 |
- |
534 |
600 |
- |
| Puberty |
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| Male |
8-18 M |
9-11 M |
30-50 D |
4-7 M |
1-2 Y |
9-12W |
42-48 D |
35-37 D |
42 D |
55-75 D |
| Female |
8-18 M |
9-11 M |
30-50 D |
4-5 M |
1-2 Y |
9-12W |
42-48 D |
35-37 D |
25 D |
55-75 D |
| Breeding season |
Nov-May |
Jan-Aug. |
YR |
YR |
Mar-Apr. |
YR |
YR |
YR |
YR |
YR |
| Estrous cycle |
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| Usual |
40 D |
Seasonal |
9 D |
- |
Seasonal |
4-6 D |
4-5 D |
4-5 D |
5 D |
- |
| Range |
16-69 D |
- |
4-20 D |
4-9 D |
- |
- |
- |
.- |
- |
6-8 D |
| Postpartum estrus |
Yes |
No |
Yes |
Yes |
No |
Yes |
Yes |
Yes |
Yes |
Yes |
| Litters/year |
2 |
2 |
S |
S |
1 |
S |
S |
S |
S |
S |
| Gestation |
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| Usual |
111 D |
44 D |
27 D |
38 D |
32 D |
24-26 D |
22-24 D |
23 D |
21 D |
23 D |
| Range |
105-118 D |
- |
- |
36-39 D |
31-42 D |
- |
- |
22-26 D |
19-22 D |
- |
| Litter size |
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| Mean |
2 |
4 |
5 |
3 |
4.5 |
4.5 |
3.4 |
4.8 |
4 |
8 |
| Range |
1-6 |
1-6 |
2-10 |
1-5 |
1-8 |
1-12 |
2-7 |
1-11 |
1-11 |
5-20 |
| Birth weight |
35 |
12 |
7 |
5.0- 7.8 |
45 |
2.5-3.0 |
1.5-2.4 |
1.3-2.2 |
2 |
2-3 |
| Eyes open |
At birth |
4-5 W |
1 D |
16-20 D |
4 W |
16-20 D |
12- 15 D |
12-16 D |
8 D |
13-17 D |
| Wean |
6-8 W |
7-10 W |
21D |
25 D |
35D |
21D |
21-28D |
21- 28D |
14 D |
l9-21D |
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| 'Abbreviations used: Y, year; M. month; W. week; 5, day: YR. year round; S several |
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©1999,
Janet Becker Rodgers, DVM, MS, DipACLAM, MRCVS
All
rights reserved.
Comments?
Send an email to janet.rodgers@vet.ox.ac.uk
