dog travelling security

Hi all, I wonder if you can help me.  I am traveling to spain via france later this week and I know in spain dogs in cars must be contained,  in a harness or cage etc.

I have an estate car and can fit a dog guard over the back of the rear seats so the dogs are contained in the very back of the car, is this sufficient legally with spanish traffic law?

It will be just perfect.

Thank you

I was advised by the local Guardia that a cage is not necessary but the dog must have a body harness which is then connected to a seat belt socket with a lead.  The harness should not go around the neck of the dog but just around the main body.  If you do have an accident then the dog will be protected and not strangled. 

Perfect solution if a dog is travelling on the rear seat of a saloon car. Not something to be recommended.             However,  when travelling in the rear area of an estate car, as per OP, then only  a cage or grill will suffice.