Laboratory Animal Care Facility (CRC)
Injection Techniques
GENERAL OVERVIEW
Mouse
Injection sites should be cleaned with a suitable disinfectant, typically isopropyl alcohol. Sterile syringes and needles must be used for all injections. The one-time use of disposable supplies insures aseptic techniques and sharp needles. Always select the smallest gauge needle possible to limit tissue trauma and injection discomfort. A 25-30 gauge needle is recommended for use in a mouse. Before injecting, check for correct placement by pulling back on the plunger of the syringe to create a vacuum. This is known as aspiration.
Rat
Same overview as the mouse except it is recommended that 21-30 gauge needles be used.
INJECTION METHODS
Various routes of injection are useful in laboratory animals. The route chosen will depend on the species, volume of sample, material to be injected and desired rate of absorption:
- Intraperitoneal This is a commonly used method for small rodents since they do not have readily accessible veins. Intraperitoneal injections should be given in the lower left or lower right quadrant of the abdomen because vital organs are absent in this area. To prevent injection of intestine, only the tip of the needle should penetrate the abdominal wall.
- Subcutaneous In most laboratory animals the most convenient site for injection is the back of the neck. A fold of skin behind the neck is held between the fingers and a needle threaded under the skin at the base of the fold.
- Intramuscular The most commonly used site for intramuscular injection is the thigh muscle. Quadriceps, rather than posterior thigh muscles, should be used for injection of irritating substances or larger volumes.
- Intravenous Intravenous injection of tail veins is frequently used for small rodents. Animals should be properly restrained. Warming of the tail is useful to increase blood flow. A 26 gauge needle or smaller is used for venipuncture in mice and a 20 gauge needle or smaller in rats. Injection of tail veins is generally accomplished by compression of the lateral tail vein by applying pressure at the base of the tail.
- Intradermal
