Repelling cats

Hi there

As much as I adore All animals, and try so hard to encourage wildlife. I have a cat problem. I encourage birds into my garden and have such a variety, I also have a little little wood mice that live under my shed. They have been there for last 6 years without any issues. I enjoy watching them pop out to eat the bird food that's on the tray on the ground. I also used to have hedgehogs. But they have stopped and squirrels that visit.

I adore my little garden and the animals that visit.

But for some reason this year I have four different cats that hound my garden. They have killed two hedgehogs and some birds. Now they (not all at once) come lay in garden at night around my shed. Obviously  trying to catch  the mice live or hedgehogs that use the hole where they used to enter the garden. I've taught my dog to chase the cats out ( no not aggressively to cause harm. Just run and bark, she doesn't bother with other animals) But she can't be in yard all night. I'd really like to try get hedgehogs again. 

I read that natural citronella spray may deter them. But I don't want to deter other animals. I also see spikey things to put down or on fences. But that may deter all the birds which land or sit there. 

Any ideas that could help please?