At least 100 vets and and veterinary nurses working for clinics owned by three large chains are unregistered, an investigation by broadcasters NOS and Omroep Brabant has shown.

Four vets were found to operate, prescribe medication and make diagnoses without a registration while over 100 unqualified nurses performed blood tests, handed out medication or administered anesthetics.

The penalty for working as a vet without being formally registered ranges from a custodial sentence of up to a year or a fine of €25,000.

Some nine veterinary workers who applied for registration but were refused started in the job anyway, while 16 nurses and one vet started the application but failed to send in the right documentation. The remaining people were not listed at all.

“Without a registration, we cannot check if a person is qualified, and there is no way of processing complaints or legal scrutiny,” said Dophie Deleu, head of veterinary professional body KNMvD.

AniCura, IVC Evidensia en VetPartners own a quarter of all veterinary clinics in the Netherlands. Of all three, IVC Evidensia employs the most unregistered staff.

The company, which was recently accused of putting pressure on staff to increase earnings, said the lack of registration of the four vets was “an administrative mistake in a complex, confusing and antiquated system.”

IVC Evidensia removed 29 staff profiles while AniCura and VetPartners changed the job titles of some of the nurses and deleted certain job descriptions.

The three chains admitted mistakes and said that registration would be a priority.

It is not clear if any animals were harmed because of treatment by unqualified staff.

In a reaction, caretaker junior minister Jean Rummenie called the results of the investigation “worrying”. The public prosecution office said “any unlawful practicing should be reported”.