Murrieta police say the 22-year-old mother Carrie McKinney had left the baby in a carrier on the floor in her friend's apartment last Saturday.
The mother and friend, Doug Ritchey, heard screaming and rescued the baby, who is hospitalized in unknown condition, police said.
Child Protective Services workers took the baby from the mother, Murrieta police Sgt. James Ganley said.
San Diego County child protective services has obtained a court order to take the infant away from McKinney, of Point Loma, Ganley said.
MCKinney had lost custody of two other children in 2008, the Press-Enterprise is reporting.
It was not immediately clear why she lost custody of her other children.
Riverside County CPS will conduct an investigation, Ganley said.
No arrests have been made in the case.
The dogs are being euthanized.