Columella, On Agriculture
7.12.1 (tr. E.S. Forster and Edward H. Heffner):
For what human being more clearly or so vociferously gives warning of the presence of a wild beast or of a thief as does the dog by its barking? What servant is more attached to his master than is a dog? What companion more faithful? What guardian more incorruptible? What more wakeful night-watchman can be found? Lastly, what more steadfast avenger or defender? To buy and keep a dog ought, therefore, to be among the first things which a farmer does, because it is the guardian of the farm, its produce, the household and the cattle.
Nam quis hominum clarius aut tanta vociferatione bestiam vel furem praedicat, quam iste latratu? quis famulus amantior domini? quis fidelior comes? quis custos incorruptior? quis excubitor inveniri potest vigilantior? quis denique ultor aut vindex constantior? Quare vel in primis hoc animal mercari tuerique debet agricola, quod et villam et fructus familiamque et pecora custodit.