Safety Issues

[Anthony Dyson]

Further to the dogs, you can buy (at least in UK, probably elsewhere,
too) a battery-powered device called a Dog Dazer which emits a very high
frequency sound which humans cannot hear but apparently stops dogs in
their tracks. It does them no harm and is claimed to be extremely
effective.
They are not especially cheap, but could offer peace of mind. The
British Confraternity of St James guide used to have an address/phone
number for the makers.
Failing that, I understand that pepper spray is available and legal in
Spain. This could have a dual role against two-legged predators as well.

And I once read (on this site ...?) about a walker who carried a can of
shaving foam which he said he used to good effect on dogs. Apparently it
sprayed out a great long string of foam which sent the dog scurrying
away.
Finally, despite what has been said on this NG, I think rabies may well
be a problem in Spain. Not a disease to be trifled with.
Happy walking!