About 80 products were completely withdrawn, removing growth promotion products of medically important antibiotics which brings the US market in line with many EU regulations.

"In the past, we had quite a lot of products that were approved for growth promotion in the pig industry that were available over the counter," said Peter Davies, professor at the University of Minnesota. "So anybody could walk into the local store and buy antibiotics. They had to be used on label, as approved, but there was no veterinary oversight of them."

Before the Veterinary Feed Directive (VFD), there were also several products that were used for treatment of animals in water and in feed that were also available over the counter. The new VFD regulation has brought all antibiotics that are used in feed or in water that are medically important, meaning they are used in human medicine and in animal medicine, under veterinary oversight.

"We're shifting from an environment of over 50 years where producers have had ready access to antibiotic products, both for growth promotion and for treating animals, to where, apart from a small number of products that are not used in human medicine, all other antibiotic uses in feed and water will have to be under the guidance of a veterinarian with whom they have an established relationship."

With the VFD, veterinarians have assumed a much broader responsibility for the oversight of antibiotic uses in the pig industry. Smaller pig producers in remote areas where it is difficult to get veterinary services have likely been most affected by the new VFD regulation, Dr. Davies said.

On the other hand, many larger pig operations already have either veterinarians on staff or have veterinarians that they have very regular interactions with.

"They already have what's called our veterinary/client patient relationship which is a legal requirement for the veterinarians to be able to prescribe," he said. "Most large producers already have regular veterinary oversight, so the impact is probably more for veterinarians in terms of workload."

Veterinarians are now responsible for generating the VFDs, maintaining records and communication with their clients. Davies noted there's also more physical farm work for the veterinarians, so their workload is going up.

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