Ticks

A friend came to visit with his dog. While here, he told me that his dog had ticks. That was four days ago. Today, while cleaning my dog's day bed, l saw many dead ticks on and under her towel and on and under my sofa. I think her flea/tick collar killed the ticks on her. I brushed her down today, but, how do I know for sure they are all gone. She has been on my bed so are the ticks in my bed? Are they in my residence? I need lots of advice. She's nine years old and never has ever had ticks or fleas. I'm in a puzzlement. How can I make sure there are no more ticks? Thanks for any advice and help. Maxine