SOP 10.9.2 - Intraperitoneal Injection in Rats

University Animal Care Committee Standard Operating Procedure

Document No: 10.9.2

Subject: Intraperitoneal Injection in Rats

Date Issued: July 7, 2011

Revision: 4

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 intraperitoneal injection in rats.


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 rat.
  • 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 mandatory for intravenous, intraperitoneal, intramuscular, intradermal, and all biohazardous injections.
  • Choose the appropriate administration route for the substance to be injected.
Recommended Needle Sizes and Volumes
Length of needle: 1/2 to 3/4 inch
  Intraperitoneal IP
Recommended Gauge
Good Practice Volume
(Max per site)
1 ml

2. Materials:

  • Sterile syringes
  • Sterile needles (21-27 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 in dorsal recumbency with the head tilted slightly downward to provide a clear view of the abdomen.
  • Identify the midline of the abdomen. The optimal side to inject IP in a rat is their right side because the rat has a very large cecum which usually lies on the animal’s left side.
  • Disinfect the site with 70% alcohol.
  • The needle should be inserted bevel up in line with the natural extension of the hip, between the two lower nipples and angled at 45 degrees to the abdomen.
  • 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.

Intraperitoneal Injection in Rats

Intraperitoneal Injection in a Rats

Alternative Intraperitoneal technique: This hold was developed for animals that are accustomed to handling. It alleviates stress to the animal, and allows for clear visualization of the needle hub.

Intraperitoneal Injection in Rats

Intraperitoneal Injection in Rats

Date New Version
07/07/2011 Created
01/24/2012 Annual Review
09/22/2015 Triennial Review
02/28/2019 Triennial Review
02/28/2022 Triennial Review
12/12/2022 Triennial Review, split apart separate injection methods, updated format and reviewed/updated maximum injection volumes


SOP 10.9.2 - Intraperitoneal Injection in Rats

Download SOP 10.9.2 (PDF 166 KB)