Hi, Shirley.

First hold the mouse by grasping on the back skin and neck with your left handle while you are holding the tail with right hand. Hold your left hand perpendicularly while you take some tissues in your right hand. Gently massage with the tissues just above genitalia. Let mouse do both excretion on the tissues by several times of massage. You can find left or right flank where you can prick your needle gentle without penetrating into the thoracic or abdominal walls while you are holding the mouse horizontally now. Inject fluid gently while massaging the injected region (If anyone help you otherwise forget about massage). After complete delivery of the fluid from the plunge, hold the syringe in dead still for 1~2 min while giving a massaging.

I also suggest making your injection solution 4-fold stronger, requiring only 25 uL injection. Even with this volume, aforementioned procedure is still valid.

Best wishes.

Hi Shirley,

What site are you doing the sub-cut injection? Are you injecting into a loose fold of skin such as on the stomach or in the scruff? What angle are you inserting the needle? Is the mouse conscious or unconscious?

100ul should not leak out of the site and you should be able to inject and remove the needle immediately after you have done the injection.

Sub-cut injections should be done in a matter of moments taking no more than 30 seconds from the time you scruff the mouse to the time you put it down.

Unfortunately without seeing your technique it is hard to tell where you are going wrong.

For scruffing technique view https://www.youtube.com/watch?v=Gs-ebUnPQEc.

For subcut injection view https://www.youtube.com/watch?v=CbVZecd831g. The viewing angle is not the best but should be enough to help.

Regards

Chris

Thank you very much for the reply, Dr. Lee!

Hi Chris, thanks a lot and sorry for the late reply! To answer your questions, I was doing the SC injection below the right upper limb (just like the video in your second link). The skin was not very loose due to my tight grasp of the mouse, but I think I was able to insert the needle subcutaneously (or maybe the needle went a little deeper into the tissue under the skin?...). The mouse was shaved beforehand so that I was able to see the injection process better. While inserting the needle, the needle was almost parallel to the flank/skin, so the angle was probably smaller than 10°. The mouse was unconscious. While injecting (50-100ul), I can see a bump forming, and when I withdraw the needle, there is usually a drop of liquid coming out of the insertion point, sometimes a big drop and sometimes small, which is causing inconsistencies among my injections/experiments.

Hi Shirley,

Have you tried lower down the body in the loose fold of shin between the hind leg and abdomen?

How far are you inserting the needle. If you are only inserting the a few millimetres past the the bevel you will probably always have leakage. If you insert at least 5mm or 10mm if possible you shouldn't have any problems

If the mouse is unconscious you could do a subcut injection into the scruff and just be careful not to stick yourself with the needle.

Lastly. Try injecting a bit slower to allow for the pressure you're creating to dissipate.

Hi Chris,

Yes exactly! I recently also found out that if I insert the needle further past the insertion spot, there seemed to be no leakage. Thanks for answering! Also I was wondering that for SC injection, after you insert the needle and reach the desired spot, do you lift up the needle to loosen the nearby skin and then inject, or do you inject directly? Thanks!

Hi Shirley Wu ,

Apologies for the very late response.

I have always inject directly but slowly.

Cheers

Chris

Hi Chris,

Thanks for the reply!

Hi, Shirley

I am also doing subcutaneous injection, and I inject the corn oil. There is a lot of leakage. Do you have some suggestions?

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