Subcutaneous injection of a substance in the mouse
Key points to note
Subcutaneous administration of material often causes minimal pain or discomfort, provided the material is non-irritant, has a near-neutral pH, and is not excessively hypertonic or hypotonic.
The most usual site for injection is over the shoulders, into the loose skin over the neck, but other sites with loose folds of skin can also be used, for example over the flank. When repeated doses of material are needed, varying the site of injection can help reduce the likelihood of local skin reactions.
It is not usually necessary to try to sterilise the skin with antiseptics – their use is almost always ineffective and they simply prolong the duration of restraint needed and may cause additional disturbance to the animal.
As with all injection sites, a new needle should be used for each animal, since this will reduce discomfort caused by the procedure and also reduce this risk of any injection-site infection. Any discomfort can be further reduced by injecting fluid that is at body temperature.
As with other routes, if repeated injections of material are needed, consider alternatives such as the use of minipumps.