We had a severe tick problem with our dogs, a golden retriever and a poodle. That, and they were both scratching like crazy.
We went to the vet in Santo Domingo, and she told us in no uncertain terms to AVOID using Flea/tick shampoo, and instead, told us to buy the cheapest gallons of shampoo and rinse you can find. (most flea/tick shampoos are murder on their skin)
The instruction were to bathe and rinse, then apply Frontline SPRAY, not drops, two day after the bath, and repeat this action for three weeks.
We also were told to spray the dogs thoroughly with a mix of 1/2 gal white vinegar and 1/2 gal bottled water, mixed with 1 teaspoon of boric acid, every day before lunchtime, for the same period of time.
And finally, give them a cod liver oil pill once every other day.
Both dogs now have shiny coats, don't scratch, and best, no ticks.