Injection

Intraperitioneal (IP) Injection

Introduction

This method of injection is used when large amounts of material are to be injected. The method is very rapid and easy if the animal is held properly. It does not require special restraining devices nor anesthesia. The material injected is absorbed slowly. Caution should be observed during the holding and injecting processes since damage to internal organs can occur if care is not taken to properly hold the animal and control the insertion of the needle. IP injection takes practice to reduce your anxiety and to eliminate possible injury to the animal. Also, the animal will frequently urinate and defecate during this procedure, so you should wear thin, form-fitting gloves to keep wastes off of your hands.

Procedure

The entire procedure will be demonstrated by the lab instructor before you attempt to inject the animal yourself.

1. Load the material to be injected into a syringe.

2. Attached the desired size needle to the end of the syringe. Loosen, but do not remove, the needle cover. Make sure the needle remains firmly anchored to the syringe tip.

3. Lift off the mouse cage cover.

4. Pick up a mouse by its tail with the first two fingers of one hand.

5. Place it on the wire cage top and allow it to pull away from you - but do not release the tail.

6. Carefully grasp the mouse by the fur/skin on the shoulders and the back of the neck with the thumb and forefinger of your other hand. Be sure to grab enough of the fur/skin to stretch it tightly enough to prevent the mouse form turning its head and biting your hand.

7. Without releasing the tail or the fur/skin, lift the mouse with both hands. Turn it over (belly side up) in the palm of the hand that is grasping the neck fur/skin. Still do not release the tail.

8.Grasp the tail with the third and/or fourth finger of the hand that is also grasping the neck fur/skin.

9. Be sure the mouse is properly restrained, then release the tip of the tail from your other hand (the hand that originally picked up the mouse by the tail). You should then be holding the mouse with only one hand, with your thumb and forefinger grasping the neck fur/skin and your smaller finger(s) holding down the tail (this can be hard for persons with small hands or with fingers that just won't flex enough).

10. Pick up the syringe with your "free" hand. Hold it so that your thumb is on the end of the syringe plunger. You will probably find it easiest to hold the barrel of the syringe between your first two fingers.

11. Hold the syringe so the needle is bevel side up, at angle of approximately 30 degrees to the skin surface and at an angle of approximately 45 degrees to the mouse's midline. The needle should be pointed at a site just above the mouse's crotch and just to the side of the midline (on the same side as the hand that is holding the syringe).

12. Without changing the position or angles of the syringe/needle and while preventing the mouse from moving (by holding it properly with your one hand), VERY CAREFULLY insert the needle (that is attached to the syringe) into the abdomen of the mouse.

If the animal starts to struggle when you get ready to insert the needle, set the syringe down (on a clean surface) and repeat the entire procedure for properly restraining the animal. You do not want to allow the animal to move while the needle is inside, as you may cause considerable internal injury.

13. As soon as the needle has entered the peritoneal cavity (a very slight "easing" of resistance to insertion of the needle should be felt), hold the animal and syringe very still and carefully inject the required amount of material.

14. Remove the needle. Turn the animal over and release it into the proper cage.

15. Destroy needle and syringe as demonstrated by the instructor.