The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind. For while other animals are each of them of use to us in virtue of one particular quality, and possess a special and distinguishing excellence, this one animal is responsible for greatest and highest points of excellence. A lion excels in courage, an ox in reliability and adaptability to agriculture, the horse in intelligence and speed, the ass and mule, as is stated by the poets, in patience and hard work; and other animals have other good points: this one animal combines the excellence of all others without one exception. He is naturally suitable for war work and the pursuits of peace, and equally fitted to be of use and to be a pleasant companion. It would not be easy, as you will believe, to enumerate all the excellences and all the services to ourselves of this animal.
— Theodorus Gaza, Laudatio Canis, via Futility Closet. (The date given there, 1482, is probably too late.) Further research turns up this article by Sophia Xenophontos on Byzantine dogs — from the dogs’ point of view. One important question pursued there: Can dogs actually sing?