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UNIVERSITY OF SOUTHERN MAINE
Office of Research Integrity & Outreach
Procedure #:
Date Adopted:
Last Updated:
Prepared By:
Reviewed By:
Procedure Title:
03-004
7/28/2003
012/16/2011
Sarah Gilliam, Animal Facilities Manager
USM IACUC Committee
Rat Procedures
1.0 Purpose: To insure that proper technique is used in order to avoid and/or limit pain
& distress to the animal.
2.0 Responsibility:
2.1 It is the responsibility of the investigator, technician, or student forming the
task to follow the procedures outlined in this document.
3.0 Applicable Documents:
3.1 Guide for the Care and Use of Laboratory Animals
3.2 SOP 03-006 Rodent Blood Collection Procedures
4.0 Rat Handling and Restraint Specifications:
4.1 Catch the rat at the base of the tail, using the thumb and forefinger.
4.1.1 Do not grasp towards the end of the tail, this can result in injury to
the animal.
4.2 Place the opposite hand over the rat’s upper body, using the thumb &
forefinger to press the animal’s forelegs toward the head.
4.2.1 Do not grasp the animal so tightly that breathing is restricted.
4.3 The other hand can then be used to restrain the hindquarters and/or the tail if
more control is needed.
4.4 An adjustable rodent restrainer can be used.
5.0 Injection Procedures: The injection site should be cleaned by swabbing the area
with a suitable disinfectant (such as betadine or alcohol). Sterile syringe and needle
are to be used for all injections.
5.1 Intraperitoneal Injections (IP):
5.1.1 If necessary, hair should be clipped. Sterile technique must be
used.
5.1.2 Can inject 5-10mls
5.1.3 Use 22 gauge needle
5.1.4 Injection is given with the rat on its back and hindquarters elevated
in order to allow the intestines to fall toward the diaphragm.
5.1.5 The injection can be given on either side of the midline.
5.2 Intramuscular Injections (IM):
5.2.1 Can inject 0.3 ml of liquid at one time.
5.2.2 Use 22 gauge needle, unless substance is viscous.
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5.2.3
5.2.4
May be administered into the quadriceps or posterior thigh.
Once the rat is securely restrained, the injection site should be
shaved & disinfected.
5.2.5 Insert the needle through the skin into the middle of the muscle &
inject the desired substance.
5.2.5.1 Hind leg injections into or close to the ischiatic nerve may
lead to unnecessary discomfort, temporary lameness, or
permanent paralysis of the leg.
5.3 Subcutaneous Injections (SC):
5.3.1 Can inject 5-10mls at a time.
5.3.2 Use 22 gauge needle, unless substance is viscous.
5.3.3 Administered into the loose skin along the back or neck.
5.3.4 Pull a fold of skin away from the underlying muscles, forming a
tent.
5.3.5 Insert needle at a shallow angle through the skin into the SQ tissue,
careful not to enter muscle tissue or pass the needle through the
other side of the tent of skin.
5.3.6 Aspirate before injecting the solution. Proper placement of the
needle will yield no aspirate.
5.4 Intradermal Injections (ID):
5.4.1 Can inject 0.1mls per site
5.4.2 Use 25 gauge needle
5.4.3 Shave and disinfect the injection site.
5.4.4 Stretch the skin between your fingers to isolate the injection site &
insert the needle just under the surface between the layers of skin.
5.4.5 Inject the liquid and a small discrete bleb or pocket of fluid will
form when an ID injection is properly administered.
5.5 Intravenous Injections (IV):
5.5.1 IV injections should normally be done through the lateral tail vein.
5.5.2 Use 26 to 28 gauge needle.
5.5.3 Can inject 0.5mls of liquid at one time, should be done slowly.
5.5.4 Anesthetize or secure rat in a restrainer. Extend the tail with one
hand to produce a flat work surface.
5.5.5 Using the other hand, insert the needle at a slight angle, making
sure the beveled edge of the needle faces outward.
6.0 Blood Collection Procedures:
6.1 The approximate blood volume for an adult rat is 20-40 mls.
6.1.1 A single blood sample is usually 2-3 mls in volume.
6.2 Please refer to SOP 03-006 Rodent Blood Collection Procedures for proper
collection techniques.
7.0 Gavage:
7.1 Use a standard rat gavage tube attached to a hypodermic syringe.
7.1.1 A ball-like enlargement should be present at the tube’s tip to
prevent injury.
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7.2 The rat should be held in a vertical position by placing a hand around the
animal’s upper body with its forelimbs crossed.
7.3 Line up tube with the ball at the level of the last rib before inserting to
determine how far the tube should be inserted.
7.4 Start the tube into the mouth at a 45o angle. As tube advances, raise it to a
vertical position.
7.4.1 Do not use force, if necessary withdraw and start again.
7.5 Once the ball is in the stomach, slowly deliver the contents of the syringe.
Once completed, withdraw the tube.
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