Mouse Basics

Mouse Basics Training
Updated 09/2017

You will have a brief quiz on this material
and will be asked questions during your
hands-on training.
You can review this material again as many times as you want.

Outline
• Biology
• Behavior
• Husbandry
• Health
• Handling
• Tools
• Safety

When promoting Animal Welfare
use the following principles:
• Decisions regarding animal care, use and welfare shall be made by balancing
scientific knowledge and professional judgment with consideration of ethical and
societal values.
• Animals must be provided water, food, proper handling, health care, and an
environment appropriate to their care and use, with thoughtful consideration for
their species-typical biology and behavior.
• Animals should be cared for in ways that minimize fear, pain, stress, and suffering.
• Procedures related to animal housing, management, care, and use should be
continuously evaluated and when indicated, refine or replaced.
• Animals should be treated with respect and dignity throughout their lives and,
when necessary, provided a humane death.
• Strive to improve animal health and welfare through scientific research, education
collaboration and advocacy.

Why mice are used in research
• Mammal of small size
• Relatively short life span
• Prolific reproductive capabilities
• Susceptibility to microbiological and chemical agents
• Much baseline data on embryology, genetics, gerontology
• Immunologic response similar to humans
• Ease of maintenance

Basic Biology
• Typical lifespan:
• Weaned at:
• Puberty:
• Gestation:
1.3-3 years
21 days of age
between 28 and 49 days
averages 19-21 days

Behavior
• Mice are social animals. Single housed mice can
become more aggressive due to a lack of contact with
other mice.

Behavior Categories
Maintenance behaviors
• grooming, eating, drinking, nesting
Investigative/exploratory behaviors
• climbing, digging, chewing, sniffing
Social interactions
• huddling together, grooming each other, scent/territorial
marking, aggression, defense, sexual behavior

Aggression
• Adult male mice can be very
aggressive towards each other.
Fight wounds are most
commonly seen on the rump
and back of the animals. When
fighting cage mates are found,
the aggressor (if known) should
be removed, or all mice
separated.
• If housing male mice together
they must be introduced at
weaning.
• Once separated, male mice
should NEVER be recombined.
This mouse
was placed
with males
three
months
older than
himself.

Husbandry
• Mice are provided a clean, autoclaved cage at
least once weekly.
• Cages include food, water, bedding and
enrichment

Caging Rules
• No more than 5 adult mice per cage
• Up to 9 weanlings weighing less than 15 grams
• Breeding pair with pups or 1 dam with pups

Health Assessment Focus
• Movement
• Is the mouse moving normally?
• Attitude
• Is the mouse behaving normally?
• Coat Condition
• Is the mouse keeping its fur groomed
or does it look spiky and greasy?
• Body Condition
• Is the mouse thin? Overweight? Have
tumors/masses?
• Posture
• Is the mouse hunched? How are the
feet placed?

Facial clues of pain
Grimace scale
Body Condition Scale

Health Concern Notification
• Blue Flag - Use to notify LAR of a potential
health concern.
• Mark with your initials, date, and a brief note
about the concern.
• Pink “Increased Monitoring” card - Placed by
LAR staff. If you see one on your animal, read
it and be prepared to make a plan of action.

Common Health Issues
Learn how healthy mice behave so you can easily spot and report a sick or in
distress animal.

Alopecia
(Hair loss)
Hair loss is normal and common in our mice. No need to report
unless irritation or wounds are present.

Barbering
A form of alopecia. You do not need to report instances of
barbering unless irritation or wounds are present.

Dermatitis
Look for scabs, redness, bleeding, or raw, weepy skin.
Notify LAR with a blue flag immediately.

Malocclusion
Misalignment/overgrowth of the teeth and/or jaw makes it hard for the individual to
eat. The teeth can eventually grow through the tissues of the face and skull. Teeth may
be trimmed if an individual is valuable to the research, but the weekly trimming
causes the animal a great deal of stress.
Notify LAR with a blue flag if noted.

Severe Malocclusion
Fun Fact: Mice eat 3-6 grams of
food per day. This is approximately
one biscuit of food. Hard food
helps wear down the continuously
growing incisors by providing
something to gnaw on.

Hydrocephalus
Hydrocephalus means “water on the brain.” This condition is assumed to
be a painful. Best to use these mice quickly or euthanize when found. The
condition needs to be documented and the Attending Veterinarian notified.
Notify LAR with a blue flag if noted, even if you are unsure.

Runt
Runts are smaller than average pups. First thing to
check is their teeth, they may not be able to eat.
There may be other conditions, or no health problems
at all.

Microphthalmia or Anophthalmia
Developmental disorder that means
“small (or no) eye”. Seen frequently in
transgenic strains, it is not something
to worry about unless the animal
seems to be in pain or distress.

The “Handbook of Clinical Signs in Rodents and
Rabbits” from Charles River has more information
and pictures on these and other commonly seen
conditions. LAR has copies available to borrow.

Recognition of Pain and Distress
Because animals cannot volunteer to participate in
medical research, we are ethically constrained to
provide humane care, and to alleviate as much pain
and distress as is possible in such animals. We must
always work with the assumption that if a procedure
causes pain in human beings it will also cause pain in
animals. The proper use of anesthetic and analgesic
drugs helps to alleviate pain and distress during
procedures. It is imperative that researchers learn to
recognize the signs of pain and distress in mice.
Inconvenient or not, the benefit of the doubt must
always go to the animal.
*This text is on iPads in the animal holding
rooms and is also available for free from the
National Academies Press.

Common Signs of Pain and Distress
The most common signs of pain and distress in mice listed in order of increasing
severity, include: (1) ruffled or “spikey” fur (mouse looks unkempt); (2) weight loss
which may be mild to severe, anorexia, dehydration; (3) ocular discharge; (4)
lethargy, depression, or reluctance to move; (5) sitting with the back in a hunched
position; (6) ataxia (uncoordinated muscle movements), regional or generalized
weakness; (7) tremors, which may be intermittent or persistent depending on the
condition of the animal; (8) hypothermia; (9) labored respiration; and (10)
cyanosis, or a blue tinge to the mucous membranes. Any animals exhibiting
combinations of 2 to 3 minor signs, or a single major sign should be euthanized
immediately.
Animals in pain and distress may not interact with their cage-mates, or may
interact with them in a more aggressive manner. They may also become more
aggressive towards human handling. Female mice may cannibalize litters in
response to pain and distressing situations. Animals may squeal when picked up or
when an affected area is touched. Persistent vocalization and crying indicates
substantial pain or distress that should be relieved immediately. Moribund animals
require immediate euthanasia.

Acclimatization
• Transportation of animals is
stressful and leads to
physiologic changes such as
increased cortisol levels.
Mice need to have
adequate time to recover
from shipping stress. 48
hours is typically required
for blood cortisol levels to
return to baseline values.
– SU mandates a waiting period
of 72 hours before working
with newly arrived animals
unless indicated in the
protocol.

Definitions: Handling and Restraint
Handling within this context is defined as dealing with a mouse by
hands, in a direct or indirect way – with or without touching the
animal. Handling should always be done in a species-specific, calm
and firm way in order not to harm the animal and to provide as
much safety as possible to the experimenter. In order to reduce the
stressful component of any handling procedure to a minimum for
both parties, the personnel involved should be dedicated to animals,
motivated and well trained.
Restraint is described as immobilization of an animal by keeping it or parts
of it, in a comfortable but safe hold by hand or by means of a physical
device. Physical restraint is performed on conscious animals undergoing
manipulations, which do not require sedation or anesthesia, but
necessitate exact positioning of the animal as well as prevention of
unexpected movements during the manipulation.

For our purposes we will refer to handling as
grasping mice by the tail for the purposes of
moving them. Restraint will refer to holding
mice in a manner that restricts body
movement for the purpose of performing a
procedure.

Common Handling/Restraint Tools
Padded forceps Restraint Tube Cone
Each animal room at SU has padded forceps. Labs may vary on other tools available.

Restraint and Handling
Juvenile and adult mice may be caught and picked up by grasping the
base or bottom third of the tail with the fingers or smooth forceps.
Once caught, the mouse can be restrained by placing it on a wire cage
lid, grasping the loose skin behind the neck and ears with the thumb
and forefingers, and holding the tail against the palm of the hand
using the fourth and fifth fingers.
Mice can also be held using a two-handed technique. Use care to
make sure that the skin around the neck is not pulled so tightly that
the mouse cannot breathe. This technique is commonly used to
quickly examine a mouse or to administer an injection. Pregnant or
obese mice should be handled gently and supported with a hand
under their feet.

Am I going to be bitten?
• Not likely
• NOTE: If bitten, it is inappropriate to throw or
drop the mouse. Be ready to overcome this
response by reviewing/rehearsing the proper
steps to take when a mouse bites. When bitten,
place hand on cage top, mouse will release bite;
return mouse safely to cage.
• The Bite & Scratch policy is posted in the vivarium
and is also available on iPads.

What about Zoonosis?
What is zoonosis? Any disease that can cross a species barrier.
Since these mice are bred in captivity, you are more likely to give
them something than they are to give you something. You still
need to take precautions, like wearing appropriate PPE.

Questions?
If you have any questions, please email Alicia & Misty at
lar@syr.edu or bring them with you to the hands on session.

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Mouse Basics

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