Here is a link showing an engorged tick on a dog:  Engorged Tick

This is a photo of the various life stages of ticks and shows a male and female tick:  Tick Life Stages

Aside from being just plain creepy, ticks can severely affect the health of your pet and you.  They can also carry disease such as East Coast Fever, Relapsing Fever, Rocky Mountain Spotted Fever, Ehrlichiosis, and Lyme Disease.  And, yes, dogs can get Lyme Disease and Ehrlichiosis. 

Therefore, it is extremely important that you check your pet daily for the presence of ticks and remove them immediately, preferably before they attach themselves to your pet.  Likewise, if you spend time out of doors, hiking or camping, check yourself thoroughly and often.

Here is a photo of a female deer tick in comparison to a dime.  Male ticks are much smaller and much harder to see:  Female Deer Tick

Here is a photo of a lyme tick:  Lyme Tick

Here is a link to a great website all about ticks:  More Tick Info

Combing your pet with a flea comb will remove ticks from your pet before they have time to attach themselves.  Because ticks are very difficult to see especially on dark coated animals, the flea comb can be invaluable.  To locate ticks that have already attached run your fingers through the animal's coat backward.  Pay particular attention to areas in and around the face and ears and in the softer undersides of your pet.  Ticks prefer soft skin areas.

If you find an attached tick, remove it gently and slowly with tweezers.  Be sure that the mouthparts are attached and destroy the tick in alcohol.  If the head does not come out, it can lead to a skin infection.  Contact your veterinarian for assistance if this should happen.