In 2008, a book was published in Spain and the USA, the author of which, Mr. Salvador Bofarull, dedicated his work... to a dog. And not just a dog, but a specific creature - Paco, known and loved by the Spaniards. This is a stray dog who lived in Madrid, black with a white chest, and is said to be a very intelligent mongrel. His name was given to him by a passerby who met the dog in front of the Church of St. Francis. The anonymous Madrid resident was attracted by the dog's cheerful behavior and said: “Hello, Paco!” (diminutive of Francisco). Later, one of the musicians called his work “Paco the Dog's Polka,” and it became very popular. Paco was portrayed by famous artists, among them L. Taberner. The Madrid newspapers of that time, El Liberal and El Imparcial, used to report on his whereabouts... The life story of this dog became the beginning of a serious and in-depth study on the use of dogs as postmen in peaceful life and on the fronts of the First and World War II. The author of this monograph pays special attention to Kamchatka, Sakhalin, Siberia, Yakutia, Alaska and Canada - regions where postal dogs have long been used very widely and to this day remain reliable human assistants. S. Bofarull cites rare documents: postcards and letters delivered by dog mail, maps of postal sled routes, old photographs. Very interesting, for example, is the ancient engraving “Dogs pulling a postal boat up the Yenisei River”: the artist depicted the Turukhansk region on it. We offer our readers a slightly shortened version of the book by Salvador Bofarulla. Please note that the terms used in this work do not always coincide with those accepted in our popular literature. This publication is interesting not only from a historical and philatelic point of view - for researchers, a wide range of readers will be happy to familiarize themselves with it.