ds1 scaring our elderly cat - help!

[shrub]

my usually very gentle sensitive ds1 (4 years) has started to chase and scare our cat. he use to ignore her, though since moving house a neighbours child we invited round took to chasing and scaring her and my ds1 has copied her. we say a short sharp 'stop - she is very old - you can stroke her'. but her influence on him has taken hold (we no longer invite her round - impossible to talk to her mother who has mental problems).this is so sad for us as this just wasn't in his nature before
any advice please......?

have you tried chasing him showing him what it is like or possible nicer option giving the cat a lot of fuss after he has chaseed the cat and ignore him

thanks gothicmama - he loves being chased so wouldn't work, but come to think of it maybe he thinks the cat will enjoy it too? good point about giving cat all the fuss - it tends to be the other way round as in the heat of the moment all i can think of is getting him away from her as quickly as possible usually bringing him indoors. thanks again