I have three bitches, and a newly turfed lawn, not a great combination ! I've read somewhere that tomato juice helps them not to stain grass, but don't know if this is true or an old wives tail. Does anyone know ? Or have any suggestions ?

If you see them weeing chuck a bucket of water over the spot straight away and it will dilute the urine and stop the brown patches. And if you do miss a few spots the grass does always grow back usually alot lusher and greener ;)