What is the symbolic meaning of Salamano's dog in the novel?

In The Stranger, the relationship
between Salamano and his dog is analogous to both the relationships between Mersault and
his mother and between Raymond and his Arab girlfriend.  The dog reminds Meursault of
his mother; therefore, the dog is a symbol for that which is lost, dead, or
abused.

First, Salamano is more heat-broken about losing
his mangy dog than Meursault is about his mother dying.  This is not to say that
Meursault does not love his mother; on the contrary, it shows that he appreciates his
mother's life and refuses to excessively mourn her death (the way that Salamano weeps
over his dog).

If The Stranger is an
existential indictment of people who choose death over life, then Salamano is guilty as
charged.  He seems to care more about the dog now that it is gone than he did when it
was alive.  Camus is morbidly poking fun at the fact that most people, like Salamano,
are addicted to the culture of death and guilt.  As a result, they refuse to live
meaningful lives.

Secondly, the relationship shows how
violence can damage relationships.  Salamano would beat his dog simply because it is
old, just as Raymond would beat his girlfriend simply because she is a woman.  Both men
harbor violent tendencies toward weaker creatures, most likely because they are addicted
to the culture of death, guilt, and suffering.

On the other
hand, the absurd hero Meursault chooses the simple pleasures of life: he enjoys the sun,
the beach, smoking, and sex; as a result, he does not need to engage in a power struggle
with those who are defenseless.