Which vein is used for intravenous injections in mice?

• A. Lateral tail vein
• B. Carotid artery
• C. Retro-orbital sinus
• D. Jugular vein

Answer: (A)

For intravenous injections in mice, the lateral tail vein is the standard access point because it is superficial and easy to visualize after warming the tail, allowing small-volume injections with relatively quick and predictable systemic distribution when performed carefully. This route is less invasive than others and suits routine IV administration with minimal surgical manipulation.

In contrast, the carotid artery is an artery, not a vein, so it’s not used for IV injections and carries greater risk. The retro-orbital sinus—behind the eye—has been used but poses higher risks of injury and animal distress and is increasingly restricted. The jugular vein can be used for IV access but is technically challenging in mice due to their small size and often requires surgical exposure, making it less practical for routine injections.