fox deterrent?

Hi, Not sure if this subject has been covered.

My 3 hens free range in the garden all day, even when I am out,but as winter is approaching I am concerned that a fox might just visit during daylight hours. Someone has told me about "Scoot" a deterrent that you spray around an area that you want to protect.
Has anybody tried it? And more importantly did it work? If not they will have to be penned up all day in a run that I don't consider big enough!!
Thanks

an interesting concept weed! However, the best way to beat the fox in to put yourself in his shoes and look over every inch of your set up -could a fox get in? -by digging or climbing or squeezing through a loose peice of wood. As Bodger says no deterent is guaranteed. This means using very strong weld mesh to prevent them chewing the wire, digging the mesh into the ground to stop digging and making sure all "furniture" like bolts etc are very secure.
I have to say I am skeptical of deterrents like the spray -as it would be natural for the fox to keep checking the area -and the fact that there is another fox would necessarily "deter" the fox anyway.
I use electric fencing run on a mains supply and I check this twice a day -I think pain is probably one of the best detterents!