Few things make my skin crawl and my mind imagine things on me like the sight of a tick. At our clinic we primarily see deer and wood ticks. While all ticks can carry illness and diseases that can affect animals and humans, deer ticks are the number one enemy because of Lyme disease.
Ticks become active as soon as the temperature reaches 40 degrees. A deer tick must be attached to its host at least 24 hours before Lyme disease can be transmitted. Advantix (keep away from cats!) and Frontline are both good tick repellents which require only one application per month. Both repellents work by killing the ticks that bite them before Lyme disease can be transmitted.
If your pet has a tick use a tweezers or tick removal instrument to forcefully pull it out. You can use your hands, but if you are not using gloves or a Kleenex wash your hands well after touching it. Ticks carry a number of diseases, some of which are transmitted by touching or smashing them. If the tick breaks off as you try to pull it out it is not a major problem. Keep an eye on the area for infection (discharge, painful, swelling), but chances are a small red bump will form as the skin works the tick head out.