When picking up a mouse from a filter-top cage, placing the wire bar lid sideways helps to:

• A. Prevent the mouse from slipping and escaping
• B. Allow one-handed handling
• C. Reposition your grasp as you take the mouse out of the cage as it will tend to hold on to the wire bar lid.
• D. Provide extra ventilation

Answer: (C)

When removing a mouse from a filter-top cage, you want a controlled, secure grip that reduces stress for the animal and lowers the chance of escape. Placing the wire bar lid sideways uses the mouse’s natural tendency to grab onto a solid edge. With the lid oriented to the side, the mouse will cling to that edge as you lift, giving you a moment to slide your hand under the animal and support its body. This makes the lift steadier and easier to complete without losing your hold. It’s not about ventilation or one-handed handling; the key benefit is giving you a reliable grip by aligning with how the mouse tends to grasp the lid.