Herts Police have appealed for information on the reported robbery in Brook Road at around 12.50pm on Friday (April 4).
It is alleged that the victim was walking along the pavement when a vehicle stopped and two people got out, before assaulting her and taking the Staffordshire Bull Terrier cross breed dog.
A 38-year-old man and a 35-year-old woman, both from Harpenden, were arrested on suspicion of robbery following an initial investigation.
They have since been released on bail while enquiries continue.
Detective Constable Lee Whale said: “I am appealing for witnesses and information following this incident where the victim is understandably shaken up after such an ordeal.
“If you saw anything that could assist us with our enquiries, please report this to police.”
Information can be reported online, or by calling 101, quoting crime reference 41/31204/25.
Anonymous information can be provided by contacting the independent charity Crimestoppers on 0800 555 111, or via the untraceable online form on its website.
