In Greek mythology, Orthrus (Greek: Ὄρθρος , "Orthros") or Orthus (Greek: Ὄρθος , "Orthos") was, according to the mythographer Apollodorus, a two-headed dog who guarded Geryon's cattle and was killed by Heracles. He was the offspring of the monsters Echidna and Typhon, and the brother of Cerberus, who was also a multi-headed guard dog.
There were other multi headed dogs other than Orthrus 
( z1 dog :mod ( z2 other ) :part ( z3 head :quant ( z4 multiple ) ) :ARG2-of ( z5 except :ARG1 ( z6 dog :name ( z7 name :op "Orthrus" ) ) ) )