The female bulldog-type was first spotted at 9pm on Monday night (November 26) on Woodside Lane in the Burngreave area. The RSPCA was called at 11.30pm.
RSPCA inspector Sara Jordan said: “One of my animal collection officer colleagues went out to this poor girl on Monday night.
“She is extremely thin, with all her ribs and pelvis showing.
“She is only a young dog but has enlarged mammary glands, which may be a sign that she has been overbred from.
“She has a very pronounced underbite, where her bottom jaw protrudes showing her teeth.”
She was wearing a purple collar with white spots and was tied to the railings with a metal chain lead.
She wasn’t wearing a tag and wasn’t microchipped as is required by law so at the moment there is no way of tracing her owner.
Inspector Jordan said: “This dog was abandoned alone, in the dark and cold in a very poor state and it’s taken some time for her to get like this.
“I want to hear from anyone who recognises her, knows someone who had a dog like this that is now missing or saw anything they think might help my investigation.
“Please call the RSPCA inspector appeal line on 0300 123 8018 and ask to leave a message for me.”