On vet's advice my dog wears a Scalibor collar whenever he crosses the channel, apparently it's the gold standard. Supposed to deal with the ticks and sand flies that are a worry where I travel. It slowly releases dimethrin for six months, but that is toxic to aquatic organisms so he's not supposed to swim with it on. Not a problem, taking it off for a few hours I don't think makes much difference, and I feel better knowing that it's not going to leach out of the collar into the water.
It's a steady slow release, not a spot-on type of treatment.
My vet prescribes Advantix for ticks and fleas in the UK, but advised that an additional Scalibor collar was the best for where I travel, such as Southern France, Spain and Portugal. Frontline apparently not so good, even in the UK.
All that I can do is take his advice, and I don't mind buying the Scalibor collars every six months. He gets a good combing every evening also. I think he might be poisonous to cats too, which doesn't bother me.
I've seen a lot of them on dogs over there. Maybe they work, I don't know.
If only there was a similar treatment regime for humans against Lyme, keds, midges, just plain ticks.