Understanding Intravenous and Subcutaneous Injections in Mice

When conducting experiments involving mice, it is often necessary to administer substances directly into their bloodstream or beneath their skin. Two common methods for accomplishing this are intravenous (IV) and subcutaneous (SC) injections. These techniques play a crucial role in various research fields such as pharmacology, immunology, and genetics. In this article, we will explore the differences between these two injection methods, their applications, and the important factors to consider when performing them.

Intravenous Injections in Mice

Intravenous injections involve delivering a substance directly into a mouse’s vein. This method ensures rapid and immediate distribution throughout the body, making it an efficient way to achieve systemic effects. However, it requires expertise and precision to avoid complications.

Before performing an IV injection, it is crucial to select an appropriate vein. The tail vein is commonly used due to its accessibility. The procedure begins with restraining the mouse and cleaning the tail with an antiseptic solution. Next, a sterile needle is used to puncture the vein and inject the desired substance. It is vital to use the correct needle size to minimize discomfort and prevent damage to the veins.

Subcutaneous Injections in Mice

Subcutaneous injections involve delivering a substance into the layer of tissue between the skin and muscle. This method allows for a slower absorption rate compared to IV injections but still provides a reliable systemic effect. Subcutaneous injections are often employed when continuous drug release or long-term dosing is required.

To perform a subcutaneous injection, the mouse is typically restrained, and the injection site is prepared by swabbing it with an antiseptic solution. A sterile needle is then inserted under the skin, and the substance is injected. The most frequently used sites for SC injections in mice are the scruff of the neck or the flank region.

Considerations for Injection Procedures

Regardless of the injection method chosen, it is imperative to prioritize the animal’s welfare and minimize any potential distress or harm during the procedure. Here are some important considerations:

  • Expertise: Proper training and expertise in the chosen injection technique are essential to minimize complications and ensure accurate dosing.
  • Needle size: Selecting an appropriate needle size based on the mouse’s size and the injection site is crucial to avoid tissue damage or complications.
  • Injection volume: The volume to be injected is another vital factor. Overloading the system with a large volume may cause stress or reduce accuracy, while small volumes might be insufficient for the desired effect.
  • Animal restraint: Gentle restraint methods should be employed to keep the mouse calm during the injection process. This can include towel wrapping or specially designed restrainers.
  • Post-injection care: Observing the mouse post-injection and providing appropriate care is crucial to monitor their response to the injected substance.


Intravenous and subcutaneous injections in mice are invaluable techniques in scientific research. Understanding the differences between these methods, their applications, and considering important factors during injection procedures ensures accurate dosing and better overall outcomes. When performed with precision and care, these techniques contribute significantly to advancing our knowledge in various fields of study.

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