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I. Purpose

The purpose of this guideline is to identify/recommend the most appropriate size needles and injection volumes for administration of substances to laboratory animals. 

II. Scope

This guideline applies to all personnel administering substances to the animals. 

III. Abbreviations/Definitions

  1. Intramuscular (IM)

  2. Intravenous (IV)

  3. Intradermal (ID)

  4. Intraperitoneal (IP)

  5. Subcutaneous (SC or SQ)

  6. Retro-orbital (RO)

  7. Parenteral – administered elsewhere in the body than through the mouth or alimentary canal (i.e., IM, SC or SQ, IV, ID, IP)

  8. Per os, by way of mouth (PO)

  9. Intratracheal (IT)

  10. Intranasal (IN) 

IV. Guidance

  1. General Administration Guidance
    1. The recommendations provided in this guideline apply for normal healthy animals. For dehydrated, aged or sick animals or for more guidance, please contact an Attending Veterinarian.
    2. Both the substance and the associated vehicle must be appropriate for the species, route of administration, and purpose of the experiment.
    3. The smallest possible needle size (highest gauge) should be used considering the dose volume, species, route of administration, viscosity, and speed of injection. The use of the smallest needle possible will limit the amount of trauma to the surrounding tissue. Needles and syringes used for parenteral injection must be from a sterile source and limited to one needle use per animal except as indicated herein: 
      1. A single, initially sterile needle may be used for IP, SQ, or IM injection of up to five rodents from any single cage if specifically described and scientifically-justified in the IACUC protocol. For each of these cases: 
        • The same product is used for all injections

        •  Any damaged or blunted needles will be discarded 

        •  If any blood or other fluids is aspirated into the needle, it will be discarded

    4.  Substances should be room temperature or body temperature prior to administration, especially when large volumes are to be delivered.   

    5.  Syringes should be of the locking type in order to prevent accidental dislodgement which may result in autoinoculation or back spray. 

    6. Used needles and syringes must be disposed properly.

    7. Subcutaneous implants including microchips and osmotic pumps must be sterilized prior to implantation.

    8. Prior to parenteral injection, the injection site should be free of visible contamination. The intended injection site may require preparation including shaving and skin disinfection. 

    9. When using animals for training exercises, it is recommended to administer the minimal volume necessary for each procedure. 

  2. Intramuscular administration (IM) 

    1. Animals should be properly restrained prior to injection. IM injections of irritating substances can cause tissue necrosis and/or pain at the injection site. 

    2. The smallest possible volume should be used for IM injections since the volume injected can physically distend the muscle and force the dose into fascial planes or subcutaneous tissues causing accelerated lymphatic drainage and altered compound absorption. 

    3. A minimum number of IM sites should be used per day, as repeated IM injections can cause muscle atrophy and nerve damage. Sites should be rotated for multiple dose administration. 

  3.  Intravenous administration (IV) 

    1. Adding large volumes of fluid to the animal’s blood supply may cause hemodilution, changes in acid-base balance, potential increase in respiratory rate and heart rate as well as diuresis and potential pulmonary edema. 

    2. For slow injections or continuous infusions, a butterfly needle or an indwelling venous catheter should be used. 

  4. Retro-Orbital (RO) Injection 

    1. RO injection may be performed on anesthetized mice if the route specifically scientifically justified in the IACUC protocol

    2. Administration of a topical ophthalmic anesthetic (e. g, Tetracaine solution 0.5%) is may be applied prior to injection.

    3. One injection is permitted per eye. 

  5. Facial Vein Injection

    1.  Can be performed on neonatal mice up to 2 days after birth. 

    2. Neonatal mice must be anesthetized with wet ice for 30-60 seconds. 
  6. Recommended Needle Size and Maximum Administration Volumes/Day 

    The table below provides guidance on administration of test substance or vehicle dose volumes. If the volumes presented below must be exceeded, consult the AV for additional guidance. Dose volumes must be IACUC approved. 

Route of Administration

Mouse

Rat

Guinea Pig

NHP Macaque

IM

0.1 ml/site

0.2 ml/site

0.3 ml/site

 0.5ml/kg/site

needle size

25-30G

25-30 G

25 G

23-25 G

ID

0.1 ml/site

0.1 ml/site

0.1 ml/site

0.1 ml/site

needle size

25-30 G

25-30G

25-27 G

25-27 G

IP

20ml/kg

20 ml/kg

20 ml/kg

Consult veterinarian

needle size

25- 30 G

23-27 G

23-25 G

21-23 G

IV bolus

(~1 min)

IV infusion

(max rate 3 ml/min)

5 ml/kg

 

25ml/kg

5 ml/kg

 

25 ml/kg

1 ml/kg

 

5 ml/kg

5 ml/kg

 

10 ml/kg

needle size

25- 28 G

23- 27 G

25-27 G

21-25 G

PO

20 ml/kg

 40 ml/kg

20 ml/kg

15 ml/kg

gavage needle size

18-24 G

18-20 G

13-30 G or

5-6 Fr

12-14-Fr

(up to 4.5 kg BW)

SC

40 ml/kg**

10 ml/kg

10 ml/kg

5 ml/kg**

needle size

25-27 G

25-27 G

23-25 G

21-25 G

RO injection

 

needle size

150 ul (max one/eye)

 

25-30 G

n/a

n/a

n/a

Facial Vein Injection

needle size

 

50 ul(max)

30 G

n/a

n/a

n/a

IT

75 ul(max)

75 ul(max)

See AV

See AV

IN

0.03- 0.05 ml/inj

0.03- 0.05 ml./inj

See AV

See AV

 

  1. Diehl KH, Hull R, Morton D et al: A Good Practice Guide to the Administration of Substances and Removal of Blood, Including Routes and Volumes.J Appl Toxicology 21: 15-23, 2001.

IACUC Approval Date: 02/19/2020

Review Date: 02/19/2020

Issue Date: 07/01/2020