A straight needle is preferred for oral gavage in an 18 gram mouse because it prevents trauma to the esophagus.

• A. False
• B. True
• C. It depends on the operator's preference
• D. Only for mice over 25 g

Answer: (B)

Delivering substances by oral gavage in mice is about placing the liquid into the stomach with minimal tissue injury, especially to the delicate esophagus. The shape of the gavage needle matters because it guides the instrument along the natural path of the esophagus. A straight needle with a rounded tip stays aligned with the esophageal axis, reducing bending, snagging, or scraping of the mucosa as it advances. The rounded tip also lowers the chance of laceration compared with sharper or irregular tips. In an 18-gram mouse, where the esophagus is small and easily irritated, this straight, smooth approach helps minimize trauma when the needle is inserted correctly and advanced gently to the appropriate depth. When a curved or misaligned instrument is used, there is a higher risk of mucosal contact and injury. Therefore, using a straight needle is the safer choice to prevent esophageal trauma during gavage.