In any animal special store you can get so-called spot-ons, these contain substances that affect the insect's nervous system that should kill them. Fleas, however, are often resistant to these drugs. And when I used these resources with my oldest dog, I kept taking ticks away from the dog anyway. Fortunately, there have been enough natural alternatives: Billy no mates (I never find a flea), Stop! (bodygaurd Aromatherapy), Quassia Spray (Nogga), garlic tablets etc. Googling creates even more possibilities.
Never give a dog BRAVECTO. Several dogs have already responded badly to this, such as getting seizures or even having to pay for death. The Radar programme (dutch television)has also paid attention to this in a broadcast in which the manufacturer denied a causal link. However, it is conceivable that it is not good: 3 months no tick and flea by the active substances. A friend of mine has a dog that hasn't had a tick for six months!! Her other dog died shortly after administering the drug.