Manual restraint of a mouse using both hands

The mouse is lifted by the base of the tail and placed on the cage lid or other solid surface with one hand and then its tail is pulled gently back. It is quickly and firmly picked up by the scruff of the neck behind the ears with the thumb and index finger of the other hand. The tail is transferred from the first hand to between the palm and little or ring finger of the other hand, then fixed. The mouse is restrained.

Preparation of the site

The area for administration is clipped or cleaned with warm water if necessary before cleaning the skin with alcohol- or disinfectant-moistened cotton. Where aseptic skin is necessary; the fur must be clipped followed by a three-stage surgical preparation: surgical soap, alcoholic rinse and surgical preparation solution. The skin is dried immediately before administration

Method intravenous (IV) administration of antigen to mice

Compounds that are poorly absorbed by the digestive tract may be given intravenously. The syringe plus needle or the catheter must first be filled with the solution to remove air bubbles. Administrations are usually made into the lateral tail veins not into the dorsal tail vein, as it is not straight. The lateral veins are readily visualized, but have quite small diameters.

The mouse is either placed in the restrainer or anesthetized and the tail is then armed with a lamp or warm towel, or immersed in warm water (40–45ºC) in order to dilate the vessels. The tail is swabbed with 70% alcohol on a gauze sponge or swab. Insert the needle parallel to the tail vein penetrating 2–4 mm into the lumen while keeping the bevel of the needle face upwards. The solution is then injected slowly and no resistance should be felt if the solution is properly administered. The injected solution temporarily replaces the blood but then should be washed away by the blood stream. If this does not happen the position of the needle is certainly not in the vein but in the surrounding tissue so it must be moved in the surrounding tissue in such a way that it then enters the vein or a new try must be made. When the intravenous administration is finished or the cannula is pulled out, the injection site must be pressed firmly with a swab or fingers to prevent backflow of the administered solution and/or blood . The recommended volume is ˂0.2 ml.

The ophthalmic plexus route is also used for intravenous administration. The technique resembles the blood collection by retroorbital sinus puncture .

Method intraperitoneal (IP) administration of antigen to mice

This is the most common route being technically simple and easy. The conscious mouse is manually restrained and is held in a supine position with its posterior end slightly elevated or the head can be tilted lower than the body. The needle and syringe should be kept almost parallel to its vertebral column in order to avoid accidental penetration of the viscera. The needle is pushed in at an approximately 10º angle between the needle and the abdominal surface in the lower quadrant of the abdomen, To avoid leakage from the puncture point, the needle is run through subcutaneous tissue in a cranial direction for 2–3 mm and then inserted through the abdominal wall. The recommended volume is ˂3.0 ml.

Method intramuscular (IM) administration of antigen to mice

This should usually be avoided, as mouse muscles are small. If necessary, it may be given into the thigh muscle with injection volumes ˂0.05 ml. The tip of needle should be directed away from the femur and sciatic nerve. The mouse is anesthetized or is manually restrained by another person. The needle tip is inserted through the skin and into the muscle. Aspirate briefly with the syringe before injection. If blood or body fluid reverses, stop the procedure.

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