How bad a scratch is it? How did he do it? I have used hibiscrub but I think we had it because our dog at the time had bad skin.
Personally unless it is a really deep gouge I would just leave well alone, especially as it is in a place where Theo can lick and keep it clean!

And No I am not a vet!

The scratch is not bad but it is a little red in the area.

Savlon is fine, also Sudocrem antiseptic cream is ok for dogs but neither are good for them to lick. Good idea to keep a bottle of Hibiscrub in the cupboard (quite cheap from the vets) as it is a good antiseptic cleaner. I would just rub a little cream into the scratch which should ease the redness and try to stop her licking it (difficult I know) My Saluki had a terrible graze on her chest recently and all down her leg which occurred when she was running round the garden and had an alteraction with a pruned shrub. I cleaned with Hibiscrub and rubbed on Sudocrem and now all healed up. Good luck.

Id (not a vet) bathe in salt water for a day or too.
I tend to use purple spray (horsey spray that drys out a area) if its too deep, & let the air get to it.

I bought some hibiscrub at boots [£9 ]

Came home and the redness has gone but still a little scratch so bathed it as best I could and will keep an eye on it........

If it dont get any better or worse a trip to the vet.......

I'd just wash it with some saline solution or Hibiscrub, my vet always says its better than using dettol and the likes, then dry it off and apply a tiny bit savlon cream, if its just a little surface scratch that should be enough.

You should price it from Equine catalouges and shops for future, it might be cheaper. I paid £5. from a feed supplier who mainly sells horse supplements and feeds but also has some dog stuff...