What is it about chocolate that makes dogs get sick from it?

[allison]

I've been knowing the fact that dogs cant have chocolate all my life, and i'm wondring why.

 

[LoLo]

Theobromide and caffeine.

 

[LoLo]

Theobromide and caffeine.

 

[princess011]

My dog eats chocolate sometimes, and it never makes him sick.

 

[princess011]

My dog eats chocolate sometimes, and it never makes him sick.