SOP 7.9.1 - Subcutaneous Injection in Mice

University Animal Care Committee Standard Operating Procedure

Document No: 7.9.1

Subject: Subcutaneous Injection

Date Issued: February 16, 2012

Revision: 3

Location: Queen’s University

Responsibility: Principal Investigators (PI), Research Staff, Veterinary Staff

Purpose: The purpose of this Standard Operating Procedure (SOP) is to describe the subcutaneous injection in mice.


Animal Care Services ACS, Principal Investigator PI, subcutaneous SC, intravenous IV, intraperitoneal IP, intramuscular IM, per os PO, per rectum PR


1. Introduction and Definitions:

The injection methods described within an Animal Use Protocol (AUP) must be followed at all times. The following guidelines provide recommended injection sites, needle sizes and maximum dose volumes. “Good Practices” include:

  • All animals securely and safely restrained prior to injecting.
  • Only three attempts per site should be practiced. If unsuccessful, allow another (trained and competent) person to collect the sample.
  • Use the appropriate gauge needle and volume for the injection site based on the size of the mouse.
  • Before injecting any substance, aspirate first to ensure appropriate placement of the needle (excluding intravenous injections).
  • Always inject with the bevel up on the needle.
  • Always ensure the substances you are injecting are sterile, and use sterile technique.
  • Every animal requires a new sterile syringe and a new sterile needle. With small volumes, it is preferable to dilute the injectable agent to a 50% or less solution to ensure accurate dosing.
  • Disinfecting the skin with alcohol is recommended but not mandatory for subcutaneous injections.
  • Choose the appropriate administration route for the substance to be injected.
Recommended Needle Sizes and Volumes
Length of needle: ½ to ¾ inch
  Subcutaneous SC
Recommended Gauge
Good Practice Volume
(Max per site)


2. Materials:

  • Sterile syringes
  • Sterile needles (26-27 gauge)
  • 70% alcohol
  • Injectable solution

3. Procedures:

  • Every animal requires a new sterile syringe and a new sterile needle.
  • Load the syringe and needle with appropriate volume to be injected.
  • Safely restrain the animal.
  • The most common injection site in the loose skin around the neck and shoulder area. Grasp the scruff and tent the skin upward. Depending on the volume to be administered, other SQ sites include the dorsolateral thorax and flank.
  • Palpate toward the bottom of the tented skin to ensure interstitial space is accessible.
  • Disinfect that injection site with 70% alcohol (if required).
  • Insert the needle (bevel up) into the base of the tented region.
  • Aspirate to ensure the placement of the needle is correct. Proper placement should yield negative pressure and no aspirate in the hub of the needle. If any fluids are seen; stop, reload with new syringe and needle, check injection site for trauma, reposition needle and attempt again.
  • After ensuring proper placement, inject.
  • If resistance is felt during the injection, stop and (slightly) reposition the needle.
  • When injecting larger volumes or viscous substances, use the largest acceptable gauge needle for the animal.

Subcutaneous Injection Mice

Subcutaneous Injection in mic

Date New Version
04/25/2016 Triennial Review
03/28/2019 Triennial Review
12/12/2022 Triennial Review, split apart separate injection methods, updated format and reviewed/updated maximum injection volumes


SOP 7.9.1 - Subcutaneous Injection in Mice

Download SOP 7.9.1 (PDF 132 KB)