A wave of unexplained cat deaths has sparked a dispute between pet owners and authorities in South Korea, with owners unconvinced that the pet food thought to be at the center of the controversy was not to blame.

According to local animal activist groups Life and Myoeon, a total of 513 cases of cats displaying similar symptoms -- acute neuromuscular diseases, high fever, elevated liver enzymes and kidney failure -- have been documented as of May 12. Of the affected animals, 181 have died.

The activists, citing owners, claimed that all affected felines have consumed cat food made by a single manufacturer from January to April this year.

The manufacturer accused is a contract-based producer behind nearly 30 pet food products from various brands.

The Ministry of Agriculture, Food and Rural Affairs, however, found no correlation between the deaths and the suspected cat food in its investigation. It tested over 50 pet food samples currently available, including those suspected by cat owners, for 78 toxic substances, seven viruses and two types of parasites and germs.

Additional tests conducted on 10 deceased cat bodies by the Animal and Plant Quarantine Agency, aiming to detect 17 types of infection, 34 substances associated with myopathic disorders, and a total of 859 harmful substances, also did not yield conclusive results.

The results suggest the recent deaths were not the result of another avian influenza outbreak, which the Agriculture Ministry identified as the culprit behind the deaths of 38 cats at an animal shelter in Yongsan-gu, Seoul, in August. That outbreak was linked to the highly pathogenic H5N1 AI strain found in cat food.

Announcing the test results, the ministry said, “Given the potential for fatalities caused by other factors, we will continue investigating potential causes and conducting tests.”

It will cooperate with relevant industry experts and civic groups to establish preventive measures and continue monitoring the issue, it added.

The government's response has failed to assuage cat owners.

Shim In-seop, the president of Life, expressed distrust in the ministry’s probe.

"The current testing system may be inadequate for identifying the problem," he said.

He claimed that the nation is witnessing a repeat of 2015, when cats that consumed certain cat food products developed bladder infections, only for it to reach an anticlimax after state-led testing failed to identify any issues with the food.

Shim added that the authorities should have promptly banned the sale of suspected cat food products upon the emergence of symptoms in over 100 cats.

"Due to their lax and irresponsible response and lack of information, cat owners had to rely solely on social media for communication," he said.

Cat owners have formed a committee and are now demanding the government and experts ascertain the precise cause through discussions with international institutions with relevant expertise.

Another civic organization People's Welfare Countermeasure Committee filed a lawsuit against Song Mi-ryung, the Minister of Agriculture, Food and Rural Affairs, on May 8, citing her failure to adequately respond to early reports of cat deaths and prevent further fatalities by imposing a ban on suspected cat food sales.

Meanwhile, in online communities for cat owners, the suspect pet food maker's name is referred to as "Voldemort” -- a nod to the character from the Harry Potter series whom it's taboo to name.

The communities have several posts asking for verification of safe cat food products or a list of potentially problematic products, while others suggest choosing imported products, expressing doubts about Korea's standards in the pet food industry.

Kim Min-ha, a Seoulite with a 12-year-old cat, breathed a sigh of relief upon checking the list of suspected brands on an online community.

“Fortunately, my cat's food wasn't on the list,” she said, reflecting on the momentary concern she felt when her cat's kidney-related ailments coincided with the emergence of the issue.