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Mice are generally afraid of people, so minimize how often you handle your mouse. When you do pick up your mouse, do so in a safe fashion. Set a treat in your palm then lay your hand flat at the bottom of its cage. When it climbs on, gently lift it up into the air. Hold your mouse close to your lap if it is not comfortable being held. You can then pet and interact with your mouse. If your mouse is squirming and nervous, place it back in its cage. Never grab a mouse by the tip of its tail and do not squeeze a mouse with your fingers. Mice are active animals that need plenty of exercise to stay healthy. An exercise wheel is vital for any mouse's cage. However, always opt for a plastic one over a wire one. Mice can easily get trapped and injured or even killed in a wire wheel. You should also provide toys. Inexpensive toys, like cardboard rolls from paper towels and toilet paper, are safe for mice to play with. You can also pick up commercial toys from a local pet store. Mice should be active and alert. They should eat and drink regularly and breathe and walk steadily. If you notice any of the following changes in behavior, see a vet:  Lack of appetite Lethargy Discharge from the eyes or nose Diarrhea Weight loss Skin lesions Overgrown teeth Extreme temperatures can cause health problems and even death in mice. Make sure you keep your mice in an area in your home that's room temperature. If anything causes a sudden change in temperature, such as a heat outage, move your mouse to a location where temperature is stable. Household pets like cats and dogs may view mice as prey. Pets like ferrets and snakes may also prey on mice. Keep mice in separate rooms from other pets and make sure their cages are secure at all times.

Summary:
Handle your mice properly. Make sure your mice get enough exercise. Watch for signs of health problems. Avoid extreme heat and cold. Keep your mice away from other household pets.