This is what should happen.

When mice smell cat urine, it sets off an alarm in their bodies and produces a stress hormone. Their pulse rate accelerates and their instinct tells them to run from the danger zone.

The reaction is triggered by a chemical found in cat urine called L-Felinine.

Mice are born with an instinct to react against L-Felinine, whenever they sense it.

But scientists at the Russian Academy of Sciences in Moscow have found a way to switch off the life-saving instinct.

The researchers exposed mice that were less than 2 weeks old to the chemical while they were being breastfed.

And when they got older, the mice did not try to escape from their feline enemies.

"This study refers to mice which are exposed to the cat odor when they are newborn, a time when they are still with their mother. The mother provides a sense of security, which they need," says Prof. Inga Neumann, an expert in animal physiology at the University of Regensburg. "So the mice do not associate the smell with danger when they grow up."

Stressed, but calm?

However, the mice were not exactly less sensitive to L-Felinine.

When they smelled the warning odor, their stress systems were still activated - but with a difference.

The mice did not respond to the danger straightaway, even if they were stressed physiologically.

"It's the same as our not running away immediately when we hear a loud noise produced by an airplane. We have learned that it's just a plane, so we don't react the way we should by instinct," says Neumann.

Mother's role

One mystery remains. The study does not say how the mothers reacted to the chemical as they were breastfeeding. It may have affected their children's behavior.

"When mothers sense the smell, they might become nervous and their children will notice that," says Neumann, adding there are other studies which have shown animals react differently depending on the behavior of their mothers.