SAMAC, Bosnia-Herzegovina — A new calamity emerged Tuesday in the flood-hit Balkans as rescue workers battled overflowing rivers and were confronted by wastelands of drowned livestock.

As the rainfall stopped and temperatures rose, the receding floodwaters revealed a harrowing sight: thousands of dead cows, pigs, sheep, dogs and other animals left behind as their panicked owners fled.

“There are tons of dead animals that we must dispose of,” Serbian Prime Minister Aleksandar Vucic told a government meeting.

The record flooding in Bosnia, Serbia and Croatia in the past week has forced a half-million people from their homes and led to at least 44 deaths. Authorities said the death toll could rise.

Bosnia declared Tuesday a day of mourning while Serbia said it would hold three days of mourning starting Wednesday.

In the northern Bosnian town of Samac, troops used ropes to pull nearly 400 dead cows out of a barn and drove the carcasses away on trucks.

In Samac, waters rose within hours, often leaving farmers with no time to free their livestock from barns or fields.

Many dead animals were found slumped over the fences they had tried to jump over.

“Dead animals are a special problem and those have to be removed and destroyed properly,” said Bosnia’s chief epidemiologist, Dr. Zeljko Ler.

Serbia’s senior veterinarian, Sanja Celbicanin, said 140 tons of drowned animals had been destroyed so far but much more work lay ahead.

Residents in both countries were told not to return to their homes before army units disinfect the area and not to eat any food from flooded gardens, orchards or barns.

“We are warning the population to drink only boiled or bottled water,” Ler said. “There are still no mass infections, but for some diseases the incubation period is 14 to 21 days.”