How Does Argus Recognize Odysseus?

Argus recognizes Odysseus by the sound of his voice.

How does Argos recognize Odysseus?

Unlike everyone else, including Eumaios, a lifelong friend, Argos recognizes Odysseus at once and he has just enough strength to drop his ears and wag his tail but cannot get up to greet his master. ... The simplicity of the relationship between Argos and Odysseus allows their reunion to be immediate and sincere.

How does Argus recognize that the beggar is actually Odysseus?

Argus used to be known for his speed, strength, and superior tracking skills, yet the Argus in front of him is weak, filthy, and on the brink of death. Argus recognizes Odysseus at once, has just enough strength to drop his ears and wag his tail but cannot greet his master.