How to kill ticks on a dog ?

Remove ticks using tweezers. Grasp the tick with a pair of tweezers, as close to the skin as possible. Be careful not to grasp any of the dog's fur. In a fast smooth outward motion, pull the tick out of the dog's skin. If done properly, the tick's head will be removed with the body.
Squeeze the tick with the tweezers to kill it.
Place the tick in a plastic bag and seal it. If you live in an area that has a high prevalence of lyme disease, Rocky Mountain spotted fever or any other tick related disease, save the tick in the baggy and bring it to your veterinarian. A veterinarian can examine the tick to determine what species it is. Different species are more likely to carry disease than others. If you do not live in a high tick disease risk area, keep the tick inside the sealed baggy and discard it in a trash receptacle.
Clean the dog's skin at the area where the tick was removed with witch hazel to kill any bacteria. Witch hazel is a better disinfectant choice than rubbing alcohol because it stings less.
Clean the tweezers with witch hazel or rubbing alcohol to remove any bacteria.
Watch your dog for symptoms of lyme disease. The most common symptoms of lyme disease in dogs is intermittent lameness, generalized pain, fever and loss of appetite. Lameness may only affect one leg and may change legs overtime. If you notice any symptoms of lameness or illness in your dog, immediately take them to a veterinarian for treatment. Symptoms of lyme disease may not develop for many months.
Watch the area where the tick was removed for signs of infection. If the area does not heal after several weeks, excretes puss or produces a foul odor, it may be infected. If you notice signs of possible infection, take your dog to a veterinarian for treatment.
Prevent future ticks by applying a topical natural tick repellent to your dog's fur. Natural tick repellents are effective and do not contain harmful chemical insecticides. You can make your own natural tick repellent at home, by mixing 1 tablespoon of almond oil with 10 drops of rose geranium oil. Apply the oil in a straight line running from the back of your dog's neck to the base of his tail. Your dog's natural body oils will spread the tick repellent to the rest of her body over the next few days. If your dog is under 25 pounds, apply about 1/2 tablespoon of the natural tick repellent. If your dog is over 25 pounds, apply 1 tablespoon of the repellent. Apply the natural tick repellent once a month, or once every two weeks if you live in a tick infested area.