I have no idea why the answer 001 answer in this way. That s totally WRONG. Please read the fact sheet inside the box. It state clearly. Depends on the weight of the dog, if you are applying on the small, medium breed. Just spot it on the back of neck under coat.
If you have a large breed (more than 25 kg) apply evenly as 3 or 4 spots along the top of the back, from between the shoulders to the base of the tail. At each spot part the coat until the skin is visible.
and it s not like drawing a line 由頸沿美龍骨咁滴落去.