I'm sorry to hear that your girl is nonweight bearing lame on her left front leg.
How long has this been going on?
Are any areas swollen or red on her affected leg?
Does she get any better with rest and then worsen the more she exercises, or does it not matter?
Was there any sort of trauma to her front leg?
Certainly with non-weight bearing lameness we need to worry about a fracture. But if there's been no trauma and you can't see any obvious swelling then that is unlikely.
There are several other reasons for front leg lameness that are found in big breed, fast growing dogs.
Elbow dysplasia (incongruity in the development of the bones that form the elbow joint or incomplete cartilage ossification), shoulder osteochondrosis dessicans (cartilage defects in the shoulder joint due to fast growth and abnormal blood supply), eosinophilic panosteitis (growing pains caused by inflammation of the outer covering of the long bones with rapid growth), hypertrophic osteodystrophy (inflammation and swelling in the growth plates), bicipital bursitis or tendonitis are all possible causes.
We tend to see all of these orthopedic problems more in puppies that are larger then normal breed standard, overweight or have a family history of these orthopedic problems.
If this has been a repeated problem for her and she is not improving and outgrowing her limp, or it is always non-weight bearing lameness and does not improve with rest, then seeing an orthopedic specialist may be best for her. She should at least see her regular veterinarian for an examination and some radiographs under sedation to determine her specific reason for lameness.
Ask your veterinarian for a referral if you wish to see an orthopedic specialist. Or here is a link to help you find one near you on your own. Leave the name section blank and the search will come up with a list of names of surgeopns closest to you: https://online.acvs.org/acvsssa/rflssareferral.query_page?P_VENDOR_TY=VETS
Some of these conditions can lead to long term arthritis if not properly handled initially.
In the meantime try and rest her as much as possible.
Use glucosamine/chondroitin products like Dasuquin or Cosequin DS and an omega 3 fatty acid such as 3 V Caps or Derm Caps ES to support joint health. I recommend an omega 3 fatty acid dose based upon the EPA portion (eicosapentanoic acid) of the supplement as if we do that the rest of the supplement will be properly balanced. Give her 20mg of EPA per pound of body weight per day. For example a 50 dog could take 1000mg of EPA per day.
Let me know if you have further questions.