OLOMOUC, Czech Republic — For Zuzana Navelkova, it was just another day at the office. She showed up for work last month and found a 2-pound bag of frozen Swedish meatballs awaiting her attention.

“There was nothing unusual, just the normal routine,” recalled Navelkova, head of the virology department at a state-financed veterinary laboratory in this sleepy Czech town about 160 miles east of Prague.

Normal, that is, until she found horse meat in the meatballs, retrieved from an Ikea furniture store in the nearby city of Brno.

The discovery, based on DNA testing, did not stir any alarm at the laboratory, which spends most of its time hunting for potentially deadly health hazards, not for food-labeling fraud.

“I would still eat these meatballs,” Navelkova said. “No problem.”

But the results set off a firestorm across Europe, pouring fuel on a slow-burning scandal that had begun weeks earlier with the first discovery of horse meat masquerading as beef in Ireland and then Britain. “We never expected this kind of reaction,” Navelkova said.

Neither, it seems safe to say, did many in Europe, where in normal times tons of horse meat are consumed every year without causing a stir. The scandal has cast a pall over Europe’s proudest achievement — a vast common market that allows the free flow of goods and services across borders — and even the very idea that Europe’s different nations can somehow work together to set and enforce common rules.

Consumers are increasingly asking a simple but discomforting question: Why, in a trading bloc notorious for regulating things like the shape of bananas and the font size on food labels, was something as simple as identifying the difference between a cow and a horse proving so difficult?

And at a time of immense strains brought on by the euro crisis and Continent-wide austerity — when new, anti-European political forces are rising in country after country — the horse-meat scandal has brought into the open the deep divisions, cultural and otherwise, that bedevil the European Union.

A meat that nearly all Britons consider revolting, for example, is cherished as a protein-rich delight by a small but loyal minority in places like Belgium, the home of the European Union’s Brussels bureaucracy and Europe’s biggest per capita consumer of horse meat. (Italy, with its larger population, eats the most horse overall.)

For a surging camp of so-called Euroskeptics in Britain, the fact that horse meat has entered the food chain through a host of middlemen and factories scattered across the Continent stands as proof of unbridgeable cultural chasms that, in their view, make the European Union unworkable.

“With 27 different countries with completely different cultural backgrounds, there is no cultural brake on what goes into our food,” said Godfrey Bloom, a member of the European Parliament for the United Kingdom Independence Party, a group that wants Britain to pull out of the bloc. “I don’t think it is possible at all to have 27 countries agreeing to and complying with and implementing” the same rules, he said during a recent hearing on horse meat in Brussels.

The union’s failure to prevent what Ireland’s agriculture minister, Simon Coveney, described as “fraud on a massive scale across multiple countries” flows from a deliberate design in the foundations of the so-called European project, an effort over six decades to push Europe’s once warring nations into a zone of peace rooted in shared economic and ultimately political sovereignty.

Under an unwieldy system intended to assure national governments that they can give up some sovereignty but not lose control, legions of officials at the European Commission, the union’s Brussels-based executive arm, churn out regulations and directives but lack the authority or resources to enforce them.

For the most part, that is the province of individual countries. This means that while Brussels may loom large in the public imagination, particularly in countries like Britain, as a meddlesome, even omnipotent authority, it is actually weak.

“Those who think that the European Union or the Commission has an army of inspectors and wardens to implement legislation in this field or any other should know that there is nothing in existence of this sort,” Tonio Borg, the union’s senior official for health and consumer policy, told the European Parliament recently.

The European Commission, he explained, is largely powerless to make sure its rules on food labeling or anything else get observed, especially in face of people determined to game the system. That job, he said, belongs to each country.

All countries in Eastern Europe except Estonia produce horse meat, but appetites for it there are waning fast, as in the West.

“I eat it occasionally, although it is not my personal favorite and I don’t search it out,” said Tomas Hrouda, the chief executive of Pribramska uzenina, a Czech food company that produces horse sausages. He said he worried that the ruckus over fraudulent labeling “sends a bad signal to customers and casts a shadow over all meat producers.”

It has also led a growing number of European food producers and stores to seek shelter in patriotism by assuring consumers that their meat comes entirely from within their own country’s borders. The French frozen-food chain Picard and the supermarkets Carrefour and Intermarche, for example, have all said they will only use all-French beef in their meat dishes.

Growing calls for mandatory “country of origin” labeling on all processed meats sold in Europe have stirred concern in Brussels about a surge in what Borg, the health and consumer-affairs commissioner, has called “veiled protectionism.” Until now, only unprocessed meat had to identify its place of origin.

The European Union’s main response so far has been to prod member states to undertake a one-month program of random DNA testing for horse meat. Brussels will cover 75 percent of the cost.

As testing and labeling rules become more stringent, however, the likelihood of yet more scandals and further blows to consumer confidence only increases.

“What do we do when it turns out that hot dogs really do contain dog?” joked a Brussels official involved in food issues. He added, “But at least that wouldn’t be false labeling.”