Early exposure to cat urine makes mice less likely to escape

Mice that are exposed to the powerful smell of cat urine early in life do not avoid the same odour, and therefore they are less likely to escape from their feline predators, later in life, a new study has found.
Researchers at the A N Severtsov Institute of Ecology and Evolution, Russia, identified the molecule in the cat urine responsible for these effects as L-Felinine.
"Because the young mice (less than 2 weeks-old) are being fed milk while being exposed to the odour, they experience positive reinforcement," said Dr Vera Voznessenskaya, one of the lead researchers behind the study.
"So they don't escape the cats when exposed to cat odour later on," Voznessenskaya said.

"We already knew that odour affects reproduction in mice: in fact, this molecule (L-Felinine) is capable of blocking pregnancy in females and reducing the size of the litter," said Voznessenskaya.
Researchers found that while the mice don't escape from the odour later in life, they still experience hormonal changes throughout their life.
"Early exposure to cat odour changes behavioural reactions to, but not physiological (hormonal) responses in the mice, which remain elevated," said Voznessenskaya.
"In fact, mice that had experienced the odour showed stress response (elevated corticosterone) to cat odours in the same way as controls," added Voznessenskaya.