Wordnet 3.0
NOUN (1)
1. 
 a dog trained to guard a house; 
The Collaborative International Dictionary of English v.0.48:
housedog \housedog\ n.
   a dog trained to guard a house.
   [WordNet 1.5]
WordNet (r) 3.0 (2006):
housedog
    n 1: a dog trained to guard a house