Mink are unusually susceptible to SARS-CoV-2, and they are farmed in long sheds holding thousands of animals in close rows — conditions in which a respiratory virus moves fast and, more worryingly, moves back into the people who work there. Infection was first documented on Danish farms on 15 June 2020, in Vendsyssel, in North Jutland.

What turned an animal-health problem into a national emergency was a variant. Statens Serum Institut identified a strain carrying mutations in the spike protein, designated Cluster 5. On 13 October, SSI chief physician Anders Fomsgaard warned that the mutation could potentially reduce the efficacy of COVID-19 vaccines — and in October 2020 the vaccines did not yet exist. They were the plan the entire world was waiting on. On 2 November, SSI's executive president Kåre Mølbak said Denmark risked becoming "a new Wuhan." The risk assessment delivered the following day concluded that continued mink breeding posed a significant risk to public health.

The industry the government was about to end was worth DKK 2.5 billion in 2019, with exports of roughly €1.1 billion a year. It was also, for well over a thousand families, the thing their parents and grandparents had built. The clause about breeding animals mattered most to them. Officials had weighed a softer option — culling most of the herd but sparing the breeding stock so the industry could be revived after the pandemic — and this was not it. Breeding lines are the accumulated work of decades and cannot simply be repurchased.

The cull ran from 30 October to 19 November 2020 across 1,182 herds. Farmers killed animals they had raised, on holdings with no future once the sheds were empty, often before anyone had explained what compensation would follow.

Danish law allowed culling inside infection zones. It did not allow the state to order the killing of healthy mink outside them, and the Veterinary and Food Agency had raised the problem shortly before the press conference. Minister of Food Mogens Jensen was told on 5 November. Frederiksen was informed on 8 November. On 10 November the authorities went back to breeders to say that culling outside the infection zones was a recommendation rather than an order — by which point most of the animals were already dead.

Jensen resigned on 18 November 2020. Frederiksen apologised repeatedly for the process while maintaining that culling all mink had been justified on health grounds, and said she would do the same again. In August 2022 she initially declined to call the affair a scandal, then six days later said plainly that it was one.

Fifteen million carcasses had to go somewhere, and the speed of the operation outran the incinerators. Between 5 and 19 November roughly three million mink were buried in trenches in military training areas — at Nørre Felding, just southwest of Holstebro, and at Kølvrå near Karup.

Decomposition produces gas. The gas expanded the carcasses, and they pushed back up through the soil at both sites, which also sat where groundwater contamination was a real concern rather than a theoretical one. The legal scholar Peter Pagh argued there had been no authority for the mass graves either; the ministry disagreed. On 21 December 2020 it was decided to dig them all up again. Exhumation began in May 2021, and the carcasses went to 13 incineration plants around the country. Food minister Rasmus Prehn called it "a troublesome and regrettable case."

The Mink Commission was established on 23 April 2021 and reported on 30 June 2022. It found that what was said at the press conference had been objectively grossly misleading, but that Frederiksen neither knew this nor intended it, and that ministers learned of the legal problem only after the decision was announced. Ten officials were criticised, among them Barbara Bertelsen, head of department at the Prime Minister's Office, and national police commissioner Thorkild Fogde. Most sanctions were later revoked. Separately, on 1 November 2021 it emerged that text messages from Frederiksen and her advisers had been automatically deleted after 30 days; the police could not recreate them.

The money outlasted the politics. A compensation agreement adopted in January 2021 set aside DKK 1.8-2.8 billion for the animals, DKK 8.9 billion for lost income and the residual value of the farms, and DKK 3-4 billion for feed centres, auction houses and hauliers. The projected total of around DKK 20 billion was revised upward to nearly 24 billion in early 2024, with payments possibly running to 2027. When breeding was permitted again from 1 January 2023, 1,223 breeders had applied for shutdown compensation and 14 for the option of restarting. The first mink returned on 14 January 2023, imported from Norway to a farm on Thyholm.