If you're looking for a man in a wolf costume, you'll be sorely disappointed with this 1925 silent film release. Archive.org says that Wolf Blood is the oldest remaining werewolf movie. However, I would argue that there is no werewolf in this movie at all. Just a guy who undergoes a wolf blood transfusion and thinks he's becoming wolf. Furthermore, the blood transfusion occurs very late in the film and I found myself waiting and waiting for something to happen and it didn't.
The main plot involves two rival lumber companies and a love triangle between the femme fatale, wolf boy and the doctor who performed the transfusion. The print of the film I saw was in remarkably good shape and was accompanied by a decent soundtrack. It stars George Chesebro who also directed the film as well as Marguerite Clayton who appeared in 179 films during the Silent Era. It is well acted and is an important historical piece that I'm glad is being preserved for future generations to watch.
"Wolf Blood" is strictly for film buffs only. It is hardly Nosferatu (1922) by any stretch of the imagination. However, the film does sow the seeds for later werewolf pictures. It also gives the viewer an appreciation for the giant leap horror films made between it and Dracula (1931) or Frankenstein (1931). If audiences were used to seeing Wolf Blood, I cannot imagine how shocked they would have been when Bela Lugosi or Boris Karloff appeared on the screen.
Download a copy of the film from Archive.org
For more info check out the film's entry in IMDB.