Olaf Stapledon, is undoubtedly best known for his amazing novels "Star Maker" and "Last and First Men", but if that is all you have read from him then you have missed out on his writings which are in a more traditional style. "Sirius: A Fantasy of Love and Discord", published in 1944, is an excellent book as well, though not on the same scale as those earlier works. It is the story of a "super sheepdog" (Sirius), who was biologically engineered with hormones, and raised along with the daughter (Plaxy) of the scientist (Thomas Trelone). It is a tragic story, in which Sirius struggles between the worlds of his human family and his canine instinct. A unique bond is formed between Plaxy and Sirius that shapes both of their lives.
"Sirius" can stand alone, or be considered part of Stapledon's vast future universe as outlined in his other works. The story is simply on a much smaller scale, and so would not in and of itself be a noteworthy event in books like "Last and First Men" or "Star Maker". Thomas Trelone is Stapledon's Frankenstein, though certainly he does not suffer from the same character flaws as Shelly's famous predecessor. At the same time, Trelone admits that he failed to consider all of the consequences of his experiment, which led to a very lonely and torn character in Sirius. Sirius cannot fit in with humans for many reasons, though Sirius himself focuses on the lack of hands. Sirius also doesn't fit with other canines, as he finds them too simple and only interesting when a female is in heat.
This book was tied for 9th on the Arkham Survey in 1949 as one of the `Basic SF Titles', which was a higher rank than "Star Maker" (tied for 13th) received. Perhaps the main reason this book is no longer as highly regarded as Stapledon's other books is due to the fact that it is a more traditional style of writing. Innovation counts for a lot with the fans of this genre, and over the course of time more traditional works can be forgotten. However, this book should not be forgotten nor should Stapledon's "Odd John", because though they are told in a more traditional manner, they still are uniquely Stapledon, and as such they are both worth reading.