Stupid I know but we never thought of this. We travelled back to the UK with our puppy via BrittanyFerries, we had to have her passport stamped that she had a worming treatment 24 hours before arriving at a UK port.

Are there any similar regulations for the return leg? We come back in 3 weeks time but never thought to ask if Spain has any import regulations.

We have never been checked when returning to Spain, there is no prior tapeworm treatment required.
Just make sure that the dogs rabies vaccination is up to date.

Thanks Big Wheels, she is up to date with all her injections, only 7 months old so they were all done before she travelled.

If you travel through the Channel Tunnel you are not checked but on the way back you are. However if again BF you are checked at the port. We came via the Tunnel two weeks ago.