Image from Novartis Animal Health
There are many species of ticks, and some are more relevant depending on where you live in the country. If you have adopted a dog from out of state, be sure to always inform your vet of their history. Should any illness arise, understanding their regional background will be very helpful in making a diagnosis.
Ticks can potentially cause bite wounds, toxocosis from tick saliva, blood loss, and/or paralysis. Paralysis is rare, and is caused by toxins secreted into the host by the female tick that is embedded close to nerve endings; this requires heavy infestation. Blood loss, due to heavy infestation, is quite obvious. Ticks feed on blood, and never underestimate the amount of blood that could be lost to heavy infestation. I don't assume the average dog who goes hiking and comes home with a tick or two should worry about blood loss, rather the potential diseases that ticks can transmit.
When removing ticks, try not to break off the organ of attachment. Hold the tick with thumb forceps as close to the skin as possible before pulling it out. Pull straight back, don't twist.
There are many tick preventatives on the market. Some will fight off mites, heartworm, and ticks. Speak to your vet and decide what will work best for your pet.
Two conditions our dogs can contract are Rocky Mountain Spotted Fever and Lyme's Disease. Rocky Mountain Spotted Fever causes fever and/or rash. Lyme's disease is spread by the Deer Tick and is found in 46 states. There is a vaccine for Lyme's; if you live in an area prone to this tick, your vet will be well-versed in this vaccine. Signs can be subclinical, but can be severe: fever, anorexia, joint involvement, round red lesions, or enlarged lymph nodes.
The most important thing regarding ticks is to understand the region you live in, and to have conversations with your vet regarding what your dog is at risk of contracting. Many things are treatable, but as always, prevention is the best medicine.
Image from Factoidz.com