Nearly 50 dogs have fallen seriously ill after chewing on contaminated bones, including 13 pets that died, the food standards regulator NVWA has warned.

The agency has issued a warning about four types of bone supplied by Barkoo, which have been linked to 47 cases reported to vets.

The dogs developed a neurological condition commonly known as “werewolf syndrome”, characterised by high anxiety, agitation and excessive wolf-like howling.

The NVWA has taken samples of bones bought by owners for analysis, while Barkoo’s parent company, German-based Matina, has withdrawn them from sale on websites Zoopla and Bitiba.

“We are carrying out analytical research into the presence of harmful substances that may have affected the animals’ neurological condition,” a spokesman said.

Facebook group

Vets ruled out a viral infection because the reports came from various places around the Netherlands. Esther Lam, whose Bernese mountain dog Bowie was one of the first to be affected, said he suddenly began barking loudly while she was making coffee.

“He ran around the living room and flew through the windows. He was urinating and very scared. It was terrifying,” she told AD.nl.

Lam set up a Facebook page to warn other dog owners after Bowie fell ill on December 17. She said at least 19 other people had told her their pets fell ill after chewing on Barkoo bones.

Bowie survived and is recovering after being given medication for the condition.