Sources : Dog
Aesop's Fables [6th century BCE +] (The Dog with the Meat and his Shadow; Perry 133) A dog seized some meat from the butcher shop and ran away with it until he came to a river. When the dog was crossing the river, he saw the reflection of the meat in the water, and it seemed much larger than the meat he was carrying. He dropped his own piece of meat in order to try to snatch at the reflection. When the reflection disappeared, the dog went to grab the meat he had dropped but he was not able to find it anywhere, since a passing raven had immediately snatched the meat and gobbled it up. The dog lamented his sorry condition and said, 'Woe is me! I foolishly abandoned what I had in order to grab at a phantom, and thus I ended up losing both that phantom and what I had to begin with.' - [ Gibbs translation]
Pliny the Elder [1st century CE] (Natural History, Book 8, 61): The domestic animal that is most faithful to man is the dog. Stories are told of the faithfulness of dogs: of a dog that fought robbers that attacked his master, which though badly wounded would not abandon the man's corpse, driving off other beasts and birds; of a dog in Epirus which recognized its master's murderer in a crowd and pointed him out by barking; of the 200 dogs of the King of Garamantes which escorted him home from exile and fought anyone who got in the way; of the dog of a condemned prisoner which refused to leave its master, tried to put food in the dead man's mouth, and when the corpse was thrown in the river, tried to keep it afloat. Only dogs recognize their master, know when someone is a stranger, recognize their own names, and never forget the way to distant places. The people of India breed dogs with tigers, but discard the first two litters as being too fierce, keeping only the third litter. A dog with rabies is only dangerous to humans during the period when the dog-star is shining; the disease can be prevented by mixing dung with the dog's food.
Aelianus [170-230 CE] (On the Characteristics of Animals, Book 7, chapter 10): Pyrrhus of Epirus was on a journey when he came upon the corpse of a man who had been killed, with his dog standing beside and guarding its master to prevent anybody from adding outrage to murder. Now it happened that this was the third day for which the dog was keeping its assiduous and most patient watch, unfed. And so when Pyrrhus learnt this he took pity on the dead man and ordered him to be buried; but as for the dog, he directed that it should be cared for and gave it whatever one offers a dog with one's hand, in sufficient quantity and of a nature to induce it to be friendly and well-disposed towards him; and little by little Pyrrhus drew the dog away. So much then for that. Now not so long after, there was a review of the hoplites, and the King whom I mentioned above was looking on, and that same dog was at his side. For most of the time it remained silent and completely gentle. But directly it saw the murderers of its master in the review, it could not contain itself or remain where it was, but leaped upon them, barking and tearing them with its claws, and by frequently turning towards Pyrrhus did its best to make him see that it had caught the murderers. And so a suspicion dawned upon the King and those about him, and the way in which the dog barked at the aforesaid men caused them to reflect. The men were seized and put on the rack and confessed their crime. - [Scholfield translation]
Gaius Julius Solinus [3rd century CE] (De mirabilibus mundi / Polyhistor, Chapter 15.8): Dogs esteem all masters equally, as is well-known from sundry examples. In Epirus a dog recognised his master’s murderer in a crowd, and revealed him by barking. After Jason the Lycian was killed, his dog scorned food, and died from starvation.  When the funeral pyre of King Lysimachus was lit, his dog threw himself into the flames, and was consumed by the fire along with his master. The king of the Garamantes was brought back from exile by his two hundred dogs, who fought those who resisted them. The Colophonians and Castabalenses lead their dogs to war, and in battle, build their front lines with them.  When Appius Iunius and Publius Sicinius were consuls, there was a dog which could not be driven away from his condemned master. The dog accompanied his master into prison; when the man was executed, the dog followed after, howling. When, from pity, the people gave him food, he carried the meat to the mouth of his dead master. Finally, when the body was thrown into the Tiber, the dog swam after it and tried to bear it up.  Dogs recognise their own names, and remember their journeys. The Indians relegate their female dogs to the forests when they are in season, so they mate with tigers. The offspring from the first conception are judged useless, owing to their excessive savagery; likewise the second. Those from the third conception are reared. - [Arwen Apps translation, 2011]
Saint Ambrose [4th century CE] (Hexameron, Book 6, chapter 4.17): What shall I say about dogs who have a natural instinct to show gratitude and to serve as watchful guardians of their masters' safety? ... To dogs, therefore, is given the ability to bark in defense of their masters and their homes. [Book 6, chapter 4.23-24] When they discover the tracks of a hare or of a stag at a point where there is a side path or a crossroad leading in several directions, they proceed to make note of the starting point of each of these trails. In silence, they weigh the problems one with the other. By applying their keenness of scent they seem to make the following observation: 'Our quarry has gone either in this direction or in that/ they say, 'or surely he has fled into this clearing. Yet he has not taken this route or that. One direction remains. There is no reason, therefore, to doubt that he has taken this route.' What men, with the aid of prolonged discussion and meditation, achieve with difficulty nature readily supplies to dogs, who weigh first the false hypothesis and when that is repudiated finally discover what is true. ... Who is as mindful of benefits and as grateful for kindness as the dog? For their masters' sake they go so far as to leap on robbers and to keep off strangers prowling at night. They are prepared, too, to die in defense of their masters and even to die with them! Dogs have often been the means of convicting people accused of homicide by showing clear evidence of the crime committed. Reliance is made in many cases on their testimony. It is related that in the early morning in a remote part of the city of Antioch a man who had a dog as a companion was found slain. The killer was a certain soldier bent on robbery. In the dusk of the morning hours he was able to find refuge in another region. The body lay unburied and attracted a crowd of bystanders. The dog bewailed with mournful cries the loss of his master. It happened that the man who committed the murder, in order to assure his innocence and make himself secure by his presence such is human astuteness joined the circle of people and with the air of displaying sympathy approached the corpse. At that moment the dog relinquished his whine of distress and assumed the role of avenger. He attacked him and held him prisoner. Raising a pitiful cry after the manner of an epilogue in a speech, the dog brought tears in the eyes of everyone present and inspired trust in his testimony. This man alone of all the men present was seized and held fast. The man thereupon became alarmed. He was unable any longer to deny his guilt. Such a clear indication of his offense could not be made void by pleas of hate, enmity, ill-will, or of injury inflicted. Since he had not succeeded in his master's defense, the dog in this case undertook a more difficult role, that of avenging him.- [Savage translation, 1961]
Isidore of Seville [7th century CE] (Etymologies, Book 12, 2:25-26): The name of the dog (canis) comes either from the Greek kuon, or from the noise it makes when barking (canere). Dogs are smarter than other animals; only dogs recognize their own names, know their masters, and will protect their master's house, die for their master, hunt with their master, and refuse to leave the dead body of their master. Dogs do not live separately from men. Dogs have two qualities: bravery or speed. (Book 12, 2:28): In India female dogs are tied up in the forest at night, where wild tigers mate with them; dogs born in this way are fierce and can overcome lions.