Stress induced by light weight back button used to prepare the rat for continuous intravenous infusion.

A light weight plastic back button used to secure a metal catheter protector to the rat's back was tested as a stressful force on the rat. The results demonstrate that the button does indeed produce a stress that is apparent from abnormal weight gain. In young rats, 150 to 180 g. the stress was alleviated by overnight fasting prior to placement of the button; older animals, 350 g. displayed an exaggerated response to its placement. While the younger rats gained weight more slowly than controls, the older animals lost weight daily for 5 days. It is our conclusion that, while the back button has many advantages over the more popular harness, the button also induces stress. Consequently, control animals should wear a button even if they are not infused.