(Brazil, Madeira, colloquial) dog (of any age) (Brazil, derogatory) a promiscuous man. (Brazil, by extension) an unfaithful man.

Yes, "cachorro" is used in Portugal, but it means a puppy, a young dog. It is used especially of baby or very young dogs, in which case de diminutive cachorrinho  is the word usually used. For adult dogs, the word used is "co".