Linda Monroe-Monarch Mastiffs
Some Mastiff pups are 'fluffy' as pups, but shed this off as they get older, usually by six months or so. A true long coat stays long and gets even longer.
Usually the coat is real soft and silky. Long fringe on the ears is usually a sign that a pup is actually going to be long haired. The long coat gene comes from the other breeds used to save the Mastiff breed from extinction after WW II, probably the Saint Bernard.
The Gene for long hair is recessive, denoted as (l), and the short coat is dominant, denoted as (L). Both parents must be carrying the recessive l gene to produce a long coated pup. The odds of having a long coated pup in a litter out of two short coated parents is 25% if both are carrying the l gene. If you breed a long coated dog to a short coated dog who is also a l carrier, the odds of having long coated pups go up to 50%. If you breed a dog to a dog that is LL or double dominant for short coat, none of the pups will have a long coat, but all will be carriers. The hard part is determining if the dog is LL, or Ll. If the male (or female) has ever thrown a 'hairy', then you know what they both are genetically. Of course you will need more than one litter to determine this if you happen to get all short coated pups due to random selection. It is not possible to determine the actual coat length of a pup until at least around five weeks old. Generally, a true "hairy" will have fringe on the ears, rump and tail as a pup and the coat is soft and silky.
I have seen long coats that were huge and gorgeous and others that were small
Long coat X dominant short coat