Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN 

It has been demonstrated that even minimal handling of mice and rats is stressful to the animals. Handling for cage changing and other noninvasive procedures causes an increase in heart rate, blood pressure, and other physiological parameters, such as serum corticosterone levels. Fluctuations can continue for up to several hours. The methods of restraint required for injections and blood withdrawals also cause physiological changes that can potentially affect scientific data. Training in the proper handling of mice and rats is required to minimize the effects to the animals.¹ Mice and rats can be restrained manually with restraint devices, or with chemical agents. Manual methods and the use of restraint devices are covered in this manuscript. All restraint methods include the process of lifting the animals from their home cage.

1. Scruffing

Mice are most often restrained using the scruffing technique, but young rats can also be restrained with this method. Adult rats are more difficult to restrain with this technique due to a more muscular neck, a reduced amount of loose skin, and an aversion to this method.

1. The one-handed restraint method is utilized most often in mouse strains that are very calm, such as the athymic nude, SCID, and some GEM strains. However, there is a greater risk for being bitten with

Routine handling for cage changing and technical procedures is a cause of stress for experimental animals. Although this type of stress is not a threat to the overall wellbeing of the animal, it can cause fluctuations in physiologic parameters that can have an adverse effect on the research data. The use of skilled personnel, proper techniques, and equipment can mitigate some of the stress.