Heather,
You cannot expect a puppy to sit still or have a good attention span at the age of 8 months. Ten minutes may not seem long to you but it is a life time for a puppy. You will be better off to break your grooming time into sessions than do it all at once. It will be easier on your dog and she will learn to enjoy grooming. If you struggle with her now she may only learn to dread grooming. Make it fun. Prasie her as you groom. After a few minutes, stop and play, give a treat then try grooming some more. Stop before she starts to struggle or she will learn that "struggling means grooming stops". (Newfs are smart and she will learn that very fast.) Depending on her attitude you may have to start back at square one and make the grooming session VERY short.
Lot of dogs struggle with grooming because the owners unknowingly hurt them while combing out tangles or mats. (I see this problem with lots of my customer's dogs) Be sure to hold between the mat/tangle and the skin as you comb so you won't be tugging on the skin and hurt her.
Hope this helps. Keep us posted on your progress.
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Jeannie and the rescues
Sara, Samantha and Panda