Wont let hes sister eat

Question
I have two bull mastiff dogs they are 4 yrs old brother and sister. My Male will not let he's sister eat. He will growl at her and not let her get close to the food bowl.I have had to almost feed her so she can eat and have tried to separate them while eating. What can I do

Answer
You need to obtain some control over this dog.  He is demonstrating dominance toward his litter mate (and they may be very close in temperament, it's never a good idea to have two dogs from the same litter or same breeding.)  This is not acceptable in your home.

Put him on behavior modification, first: this involves using positive reinforcement training (go to ClickerTraining.com).  Teach both dogs, separately, one solid behavior ("sit" is the easiest but use a different word.)  When both have obtained a strong conditioned response and can always, 100% of the time, comply with your command to 'sit" for treat/praise, begin making them both EARN EVERYTHING.  Both dogs must "sit" to be petted, played with, let in/out, ALL the time.  This is called Nothing In Life Is Free (NILIF) and it works by psychologically demoting the dog(s) while promoting you in a manner that allows the dog to seemingly "choose".  Voluntary acquiescence to leadership is the only way to obtain "dominance" in any dog, as this is the natural manner in which dogs live with one another.  NILIF will also help both dogs to feel more emotionally secure because you are clearly in charge.

Feed these dogs separately, in separate rooms, at the same time.  Prepare the food, give the male his food first (and after the training, NILIF: make him "sit" before he gets it), then take the female and her food into another room (where they cannot see each other).  Give both dogs fifteen minutes to eat (and feed twice daily, once is not sufficient; a hungry dog can present much more problems.)  After the fifteen minutes, go to the female first.  If she is done, remove the empty bowl; if she is not, distract her with a toy and remove the bowl (do NOT just take it away from her.)  Then repeat this with the male.  You may have to continue feeding them separately for some time.