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How to Identify Rodents by Ear Notch

Medical research relies on mice and rats, and they must be discernible from each other when they are kept in a cage. This can be done in a number of ways, including tattoos, shaving, microchipping and ear punching. With ear punching, patterns are created with a hole punch, and the patterns correspond to different numbers. Only the numbers 1 through 299 can be made with the punch system, and some potential downfalls exist as holes can be manipulated.

Instructions

- 1
  Record the position of the notches in the mouse's left ear. This will correspond to the tens digit. A complete single hole at the top stands for 10, a complete single hole in the middle means 20 and a complete single hole at the bottom is 30. A notch in the edge of the top is 40, one in the middle edge is 50, and one in the bottom edge is 60. Two notches in the top edge is 70, two in the middle edge is 80 and two in the bottom edge is 90.
- 2
  Record the position of the notches in the mouse's right ear. This will correspond to the ones digit. A complete single hole at the top stands for 1, a complete single hole in the middle means 2 and a complete single hole at the bottom is 3. A notch in the edge of the top is 4, one in the middle edge is 5, and one in the bottom edge is 6. Two notches in the top edge means 7, two in the middle edge means 8 and two in the bottom edge means 9.
- 3
  Inspect the middle of each ear. A hole in the center of the mouse's right ear stands for 100, and a hole in the center of mouse's left ear means 200.
- 4
  Combine the notches to form the mouse's identification number. For example, a mouse with two notches in the middle edge of the left ear and a complete hole in the top of the right ear would be number 81, since two middle-edge notches in the left ear translate to 80 and the hole in the top of the right ear is 1.

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