| 2 days |
Purring begins |
| 10–14 days |
Eyes open |
| 2 wk |
Age at which separation from mother leads to fearful/aggressive behavior to cats/humans |
| 2–4 wk |
Closeness of other kittens has a calming effect |
| End of 3rd wk |
Kittens able to recognize their mother by sight and smell |
| 3 wk |
Queen begins to teach predatory behavior |
| 3 wk |
Kittens eliminate voluntarily |
| 3–7 wk |
Age at which singleton kittens emerge from nest box |
| 3–4 wk |
Normal social play behavior starts |
| 4 wk |
Age at which kittens exposed to another species (e.g., dogs) show no fear at 12 wk |
| 4 wk |
Age through which kittens cannot retract their claws |
| 5 wk |
Age at which kittens will use scratching material if provided |
| 2–5 wk |
Early period for social play. Early exposure to humans essential |
| 5–6 wk |
Kittens independent in their ability to eliminate and find suitable substrates. Appropriate materials should be provided |
| ~6 wk |
Adult-like response to visual/olfactory stimuli, including the silhouettes of adult cats/adult cat urine |
| 5–7 wk |
Middle period for social play. Continued exposure to and play with humans/other species essential |
| ~6 wk |
Gape/Flehmen response appears (open mouth sniff to volatilize compounds through the vomeronasal organ) |
| 7 wk |
Gape/Flehmen response fully developed |
| Birth to 45 days |
During this period, if kittens are handled regularly, their approach to unfamiliar objects is rapid and more time is spent with objects and environment at 4–7 mo |
| 5.5–9.5 wk |
Age at which if kittens are handled by multiple people less fear is shown later/more interest in people later. More complex interaction recommended |
| 7 wk |
Kittens begin to cover their urine/feces if they are going to do so |
| 7–10 wk |
Late period for social play. Last age at which first exposures to humans can still readily ease the extent to which cats are comfortable with humans. More time/day with humans than required earlier to get the same result |
| By 60 days |
Object play increases |
| 4–12 wk |
No sex differences in social play behavior |
| 6–12 wk |
Pounce, belly-up, and stand-up displays are 90% effective in obtaining play response from another kitten |
| By 12 wk |
Social play patterns become more associated with predatory behavior/social fighting |
| Birth to 12–14 wk |
Handling kittens for only 15 min/day produces kittens more solicitous of people |
| 14 wk |
Postsocial play period |
| 14 wk |
Social fighting may start |
| 12–16 wk |
Sex differences appear in social play behavior |
| 12–14 wk |
Social play behavior begins to decline |
