ML from what i've been reading a grade 1 murmur is this.
What is a benign or “innocent” murmur?
Some heart murmurs are called benign (or innocent or physiological), meaning there is no apparent heart disease that explains the murmur. These murmurs are often seen in puppies, and can occur in cats of any age. They are uncommon in adult dogs. Benign murmurs are usually soft (rather than loud), and can be intermittent. Benign puppy murmurs will generally disappear by 12 to 15 weeks of age. Murmurs associated with anemia or excitement are also considered benign murmurs.
i'm thinking i'd get a second opinion,,i was reading also that stress can show as a grade one murmur. Not a clue about the limp.