Although the book is a work of fiction, Salten did some research for it: he was allowed to follow the dog training of the Swiss army.

[4] The most remarkable omissions are the following: On the other hand, the death scene of a war horse, which takes a page in the German-language edition,[7] has been reduced into nine lines in the English translation.

Although the book is labeled as a biography (Das Leben), it does not end with the death of the protagonist — it merely recounts the whole story of Renni's career as a military working dog.

[10] A contrast to Georg is Karl Stefanus who owns Renni's brother Pasha and who beats his dog constantly and finally shoots the poor animal to death.

Other subsidiary characters include Georg's mother Maria; Bettina, a service girl; Augustin Flamingo, a deceived husband; the Russian family Safonov with their six children; and Voggenberger who raises dogs.