Mouse Injections: IV, IP, SC and Beyond, Day 48

In preclinical studies, accurate dosing and proper administration routes are critical to ensure reproducibility and animal welfare. Common injection routes include 𝘪𝘯𝘵𝘳𝘢𝘷𝘦𝘯𝘰𝘶𝘴 (𝘐𝘝), 𝘪𝘯𝘵𝘳𝘢𝘱𝘦𝘳𝘪𝘵𝘰𝘯𝘦𝘢𝘭 (𝘐𝘗), 𝘢𝘯𝘥 𝘴𝘶𝘣𝘤𝘶𝘵𝘢𝘯𝘦𝘰𝘶𝘴 (𝘚𝘊) 𝘪𝘯𝘫𝘦𝘤𝘵𝘪𝘰𝘯𝘴, each chosen based on pharmacokinetics, drug solubility, and experimental design [1]. 

For 𝘵𝘢𝘪𝘭 𝘷𝘦𝘪𝘯 𝘪𝘯𝘫𝘦𝘤𝘵𝘪𝘰𝘯𝘴, a key step is pre-warming the mouse using a red light lamp or heating pad to dilate veins and improve visibility. BALB/c mice, due to their lighter tails, are generally easier to inject than darker-coated C57BL/6 strains [2]. Proper restraint is essential — firm but gentle. A slow or hesitant approach increases stress, leading to elevated catecholamine release and, in severe cases, cardiac arrest [3]. 

𝘐𝘯𝘵𝘳𝘢𝘱𝘦𝘳𝘪𝘵𝘰𝘯𝘦𝘢𝘭 𝘪𝘯𝘫𝘦𝘤𝘵𝘪𝘰𝘯𝘴 are performed by holding the mouse at a ~30° angle and gently inserting the needle into the lower right quadrant to avoid puncturing organs.  

𝘚𝘶𝘣𝘤𝘶𝘵𝘢𝘯𝘦𝘰𝘶𝘴 𝘪𝘯𝘫𝘦𝘤𝘵𝘪𝘰𝘯𝘴 are ideal for depot drug delivery, performed by lifting the dorsal skin to create a ´tent.´ 

𝗔𝗻𝗲𝗰𝗱𝗼𝘁𝗲 
During my early training, I practiced IV injections under supervision of a certified gastrointestinal surgeon. We used only PBS, but I remember puncturing the vein several times — until the tiny mouse heart stopped. Though the mouse was scheduled for sacrifice after my practice, that moment reminded me of the ethical weight of animal research for the human health.   

𝗤𝘂𝗲𝘀𝘁𝗶𝗼𝗻: What do you think is the most challenging injection route — and why?   

Stay tuned for 𝗗𝗮𝘆 𝟰𝟵: 𝗦𝗮𝗺𝗽𝗹𝗶𝗻𝗴 𝗮𝗻𝗱 𝗩𝗶𝘀𝘂𝗮𝗹𝗶𝘇𝗮𝘁𝗶𝗼𝗻 – 𝗕𝗹𝗼𝗼𝗱 𝗮𝗻𝗱 𝗢𝗿𝗴𝗮𝗻 𝗖𝗼𝗻𝗰𝗲𝗽𝘁𝘀 𝗶𝗻 𝗠𝗶𝗰𝗲   

𝗥𝗲𝗳𝗲𝗿𝗲𝗻𝗰𝗲𝘀: 
1. PMCID: PMC3189662 
2. https://www.criver.com/products-services/find-model/cd-1r-igs-mouse?region=23 
3. https://archive.measuringbehavior.org/mb2014/files/2014/Proceedings/Hawkins,%20P.,%20on%20behalf%20of%20-%20MB2014.pdf   

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