Officials in Baltimore, Maryland, have seized 19 horses belonging to traditional street vendors who sell produce from horse-drawn carts.
Health officials were unhappy about the conditions in which the animals were being kept in stabling under a bridge in the city.
The officials told local media they found standing water, mud and generally unsanitary conditions at the site.
The street vendors have been a common sight on Baltimore streets since the 1800s.
Reggie Scriber, deputy commissioner of housing and community development, told media: "We found animals laying in their own manure. It was time to make a determination."
City officials still hope to work with the vendors to come up with a solution, but said protection of the animals was the main priority.
The vendors have accused the city of failing to keep its promises over the provision of stables.