Table I. SNAP Guidelines.
Guidelines for SNAP. Each of the eight tests (A–H, depicted in Fig. 3) has a scoring range of 0–5, based on these guidelines. The SNAP score is the sum of the scores derived from all eight tests.
| SCORE: | 0 | 1 | 2 | 3 | 4 | 5 | |
|---|---|---|---|---|---|---|---|
| A. | Interactions | Avoids being handled | Responds quickly only after briefly touched | Freezes before escaping | Responds after multiple nudges | Only moves head | Comatose |
| B. | Cage Grasp | Both paws release simultaneously | CL paw first to release <50% of grasps. Struggles or an otherwise active, alert mouse that does not grasp. | CL paw first to release >50% but <100% of grasps | CL paw always first to release | CL paw does not grasp | Does not grasp with either paw |
| C. | Visual Placing | Once aware of ledge, arches back & reaches out with both forepaws | May reach with both paws but IL leads. Twists body. Taps CL paw | Occasionally does not reach with CL paw | Does not reach with CL paw at all | Head not raised and neither paw reaches | Comatose |
| D. | Pacing or Circling | Random directions | Freezing, but able to guide into either direction | Turns in one direction predominantly | Pacing, obstinate progression in same direction | Tight circling | Rolling |
| E. | Gait and Posture | Normal gait & posture | Occasionally notice CL limb abduction, but inconsistent or also observed IL | CL limb abducts when walking or stays caudal to body when mouse stops | CL limbs knuckle or too weak to support weight of mouse | Drags CL limbs | Recumbent |
| F. | Head tilt | No tilt | Ambiguous head tilt | Occasional head tilt noticed | Obvious head tilt | Torticollis | Recumbent |
| G. | Visual Field | Responds to visual stimulus bilaterally | No response but an otherwise active, alert mouse and/or has other indications of normal vision | <50 % CL responses and >50% IL responses | Consistent positive IL response, consistent lack of CL response | No response on either side and other indications of visual loss | Comatose |
| H. | Baton | Normal | An otherwise alert, active mouse that struggles or does not grasp. Tosses applicator. Loose CL grasp | Occasionally does not grasp with CL paws | Frequently does not use CL paws | Does not use CL paws at all | Unable to grasp swab |
*
CL, contralateral IL, ipsilateral