Table 2 Ethogram used to score puppies’ responses to the stranger approach test^4,29.

Orientation

Orientation

The puppy acknowledges the experimenter (i.e., makes eye contact/ is oriented toward) within 7 s.

No Orientation

The puppy does not acknowledge the experimenter’s presence within 7 s (or the duration of the step).

Response

Approach

The puppy moves toward the experimenter (i.e., takes steps toward them, or leans toward them if they cannot step any closer).

Ambivalent approach

The puppy approaches and retreats or approaches but then stops before reaching the experimenter.⁴²

No approach

The puppy does not approach (i.e., does not move toward the experimenter).⁴²

Modifier

Affiliative behavior

Any behaviors exhibited by the puppy intended to facilitate the establishment or reinforcement of a social bond. Examples include approaching the experimenter while maintaining eye contact and/or making physical contact (e.g., licking, touch) with the experimenter.

Gregarious: The puppy jumps up or ‘scrambles’ at the front of cage and/or attempts to cross/ crosses the front barrier of cage and/or exhibits repeated physical contact with the experimenter (e.g., repeatedly licking, jumping on hands, etc.) and/or approaches the experimenter while exhibiting intense tail wagging.

Undisturbed

The puppy engages in an active behavior (e.g., sniffing, eating, etc.) when the step begins, then acknowledges the experimenter’s presence and returns to the same behavior.⁴²

Avoid

The puppy avoids the experimenter (i.e., moves away from them, turns their head in the opposite direction).⁴²

Stationary

The dog is not moving while in a particular posture (e.g., sitting, standing or lying) though ear, eye, tail posture or facial expression may change.

Posture

Neutral

The puppy’s ears, tail and body are held in positions that are normal for their breed and age under conditions where they are not experiencing states of either positive or negative arousal.

Low

“Back rounded and/or legs bent…, head lowered.”⁵⁴

Additional

Fight/ Aggression

The puppy exhibits behaviors that are injurious to or indicative of intent to inflict harm on another (e.g., lunging, growling, teeth baring, etc.).

Bark

Negative affect: short duration, low frequency vocalization associated with avoidance, aggression, frustration, etc.

Positive affect: short duration, low frequency vocalization associated with play, greeting, excitement, etc.

Stereotypic behavior

The puppy performs a pattern of behavior repeatedly and with no variation in its expression (e.g., pacing, circling, etc.).⁴²