Transcript for Teen and Guide Dog Beat the Odds
-- -- a teenage girl thinking about the day you'll get your driver's license going to see movies with your friends playing sports -- love. Now imagine that all changes because of a degenerative and untreatable disease that is exactly what happened to a young woman I met recently but thanks to one extraordinary four legged -- she's back to doing what she loves her. Sixteen year old -- donor loves riding with her dog Chloe. -- but -- and -- aren't -- ordinary running partners fully CME's guide -- CME a high school cross country athlete is blind. How long you've been running. -- earnings for the sudden in invented by bank. My vision started going back for months she and her family didn't know what was causing the decline. It was a pretty tough time -- -- was tough on -- was definitely tough on us she was diagnosed with star guards disease an inherited condition that causes central vision loss. And renders its sufferers legally blind. Losing her sight has been so trying to lose someone so young. There was one thing that you couldn't sleep that's just one more time and have a good look 11 time there was nothing. The problem pulling. My failings since -- -- tough things. CNN -- -- my face it and I don't know let me look like. And for any teens learning that you can't get your driver's license can be devastating. That was kind of -- tough -- because. And that's something every teenager for -- Running was still an option if you love something enough and you'll definitely didn't even if you have struggles with them. And Sammy doesn't just run she runs cross country through the wallets for miles on end the that's where Chloe came in. Since Sammy daughter last summer they've been training nonstop learning to move together and build up -- endurance trying to get a person. To be dedicated. I can't imagine what it would require a puppy -- unless it's been a huge learning experience but she really is doing great job in the state initially wouldn't let CME and only one on the team. -- look out for her and one. We've devised a plan where she could. Possibly run in the competitive situation is sanctioned event. Meanwhile Chloe was fitting right in on the team watches -- takes part in this pre race ritual. We had 48 runners on the team and then came clothing so where and we have 49 runners. Thrown. And though she is all work on the course when the harness does Hamas teach her to -- change she didn't want -- people caught. -- an irresistible. He came. -- -- Finally after all of their hard work -- the time came for standing -- to run their race. -- -- -- -- and then learning. Look at that date Sammy ran her personal bags that's the best she's ever run. And India and -- -- teen and her -- keep their goal and crossed the finish line together. -- just faces every day was. Do you most positive attitude we could ever hope I'm really happening -- inspiration admirable because. He. Really can be anything. And Sammy is just happy teenager I've never met smile security here now there are some different rules for them they have to start at twenty seconds after the rest of the team after when their running so that the dog doesn't get entangled with the other runners but we talked about that harness -- the harnesses on no one can touch Chloe Chloe is solely. Focus on Sammy but once he -- what apple wants an artist of -- -- puppy is adorable.
This transcript has been automatically generated and may not be 100% accurate.