"I saw the poor horse that passed and the other horses forced to stand in the rain while it was loaded onto a truck."
Photos shared on social media by Melbourne Against Horse-Drawn Carriages show the horse lying on the wet road under two blankets.
Animal Justice MP Andy Meddick spoke out after seeing the image, calling it "totally preventable".
"To this poor horse - I am just so sorry.
"The death of a carriage horse in Melbourne's CBD is truly heartbreaking.
"The worst part is, it was totally preventable. Carriages should have been completely banned from the city many years ago.
"Horses and cars on busy city streets don't mix. It's that simple. It isn't just an animal welfare issue, it's a road safety issue too.
"The Minister for Roads and Melbourne City Council must work together to make this happen, rather than passing responsibility back and forth to each other."
Melbourne Against Horse-Drawn Carriages said if nothing was done to end the horse-drawn carriage trade it would take action.
"If no serious action is taken in the coming days to end the Melbourne horse-drawn carriage trade, we will take action against the City of Melbourne outside the next Town Hall meeting."
Locals were quick to denounce the service with many calling it "revolting".
"What a truly revolting life for a horse. They deserve better than this," one said.
Another added: "It's so upsetting that we still allow these poor horses to carry people around our city. We do not need this. It's barbaric and must stop!"
In 2017, the City of Melbourne stopped providing permits for horse-drawn vehicles in some parts of the CBD.
The carriages are still able to operate on the road network because they are classified as a vehicle under Victorian Road Rules.
