then said culain , " have all thy retinue come in , o conchubar ? " and when the king said that they were all there , culain bade one of his apprentices go out and let loose the great mastiff that guarded the house . now , this mastiff was as large as a calf and exceedingly fierce , and he guarded all the smith 's property outside the house , and if anyone approached the house without beating on the gong , which was outside the foss and in front of the drawbridge , he was accustomed to rend him . then the mastiff , having been let loose , careered three times round the liss , baying dreadfully , and after that remained quiet outside his kennel , guarding his master 's property . but , inside , they devoted themselves to feasting and merriment , and there were many jests made concerning culain , for he was wo nt to cause laughter to conchubar mac nessa and his knights , yet he was good to his own people and faithful to the crave rue , and very ardent and skilful in the practice of his art . but as they were amusing themselves in this manner , eating and drinking , a deep growl came from without , as it were a note of warning , and after that one yet more savage ; but where he sat in the champion 's seat , fergus mac roy struck the table with his hand and rose straightway , crying out , " it is setanta . " but ere the door could be opened they heard the boy 's voice raised in anger and the fierce yelling of the dog , and a scuffling in the bawn of the liss . then they rushed to the door in great fear , for they said that the boy was torn in pieces ; but when the bolts were drawn back and they sprang forth , eager to save the boy 's life , they found the dog dead , and setanta standing over him with his hurle , for he had sprung over the foss , not fearing the dog . forthwith , then , his tutor , fergus mac roy , snatched him up on his shoulder , and returned with great joy into the banquet hall , where all were well pleased at the preservation of the boy , except culain himself , who began to lament over the death of his dog and to enumerate all the services which he rendered to him . " do not grieve for thy dog , o culain , " said setanta , from the shoulder of fergus , " for i will perform those services for you myself until a dog equally good is procured to take the place of him i slew . " then one jesting , said , " cu - culain ! " ( hound of culain ) and thenceforward he went by this name . 
setanta did not ring the gong before approaching the house .
why did the dog attack setanta ?
why did the dog attack setanta ?