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.
Same overview as the mouse except it is recommended that 21-30 gauge needles be used.
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:
Information from AALAS learning library