Dog Food is a slang term used to refer to Heroin. This slang is heavily heard in rap music by rappers who used to sell or be around Heroin.
Dog Food Example
In Future’s Hip-Hop song, Blood On The Money , he raps “My hood, they treat me like I'm El Chapo. I keep that dog food like I'm Ralo. I had the warrant in Clayco and beat the case.”