Your dog may be declared menacing because it has attacked a human or a dog or because it has rushed a person.
Normally then the dog will need to be kept on muzzle and leash at all times it is outside your premises, though a lesser form of restriction can be argued for in place of these usual restrictions imposed by a menacing dog declaration. But usually the dog therefore will not be chasing balls in the park or running after sticks anymore. Your dog loses much of its freedom upon a menacing dog declaration being imposed.
Melke Legal is experienced in contesting such a declaration in VCAT and negotiating such declarations with councils.