Many toads produce a toxin from glands in the skin, so dogs get a most unpleasant taste, and with some species worse effects.
The UK common toad just tastes awful, and a dog will foam at the mouth and be distressed. UK frogs don't have the same effect.
In the UK, common frog, common toad and the two common newts are protected only from unlicensed sale. The common reptiles are protected also from death and injury.
So if you allowed your dog to harm a reptile, that would be an offence, but not for those common amphibians, unless you then sold the bits.
The rarer UK species of both amphibians and reptiles are protected very much more strongly.