Table 1.

Definitions of morphine withdrawal signs used for behavioral ratings

Counted signs
Activity	Crossing of a quadrant mark
Rearing	Lifting the forepaws off the ground
Teeth chattering	Teeth grinding or rapidly opening–closing of jaws
Shake	Shaking of the head only or rest of body (wet-dog shake)
Grooming	Using limbs to manipulate the head or body
Jumping	Raising all limbs off the ground rapidly
Digging	Using the forepaws to displace the bedding
Freezing	Immobility for >10 sec
Hopping	Sudden lurch forward often accompanied by a vocalization
Rubbing	Moving the jaw or the torso on the ground
Checked signs
Diarrhea	Watery feces
Ptosis	Squinting of the eyes
Irritability	Vocalization when placed into or out of the test box
Lacrimation	Appearance of a brown excretion from the eyes
Rhinorrhea	Appearance of a brown excretion from the nose
Abnormal posture	Lying on the side; writhing or hunching of body
Penile erection	Evidence of protrusion of the penis
Explosive running	Extreme horizontal and vertical locomotor activity