Stubby was of some kind of pit bull, but Bostons were new and not like now, often called Boston Bulldogs or Boston Bull Terrier. They were of fighting dog stock. However, Stubby was decorated purely for fun by Pershing and was really nothing more than a mascot.
Slight modification to comments about Pershing, as per link later, but the “for fun” label remains. The dog wasn’t even officially allowed. So no real war dog.
General Pershing Lands In France: June 28, 1917 - General Pershing lands in France as Commander of the A.E.F. The French Officer behind general Pershing is General Peletier, the civilian to the left is Monsieur Rene Besnard.