No. In the UK, there are very strict regulations on what can be used. The emphasis is on reducing pests and disease through good hygiene and cultural conditions, e.g. avoiding monocropping, growing local varieties that are more suited to the local climate, providing 'beetle banks', flower banks etc which encourage beneficial insects such as pollinators and pest predators, improving soil structure and fertility via natural means (crop rotation, 'green' manures (crops which are grown specifically to be ploughed into the ground to improve fertility and structure) plus a lot of manual labour - e.g. conventionally grown crops will be sprayed several times with a herbicide to kill weeds - organic crops rely on hoeing and hand weeding! A very limited number of treatments are available for use in extreme cases; these are less toxic than the chemicals used by conventional farming, and you have to demonstrate why using them was the last resort. Failing to comply with the very strict regulations will result in a loss of the farm's organic certification.
In the same way, routine medication of livestock is not permitted - the aim is to avoid illness through low stocking density and good animal husbandry. Animals requiring medication are either unable to be sold for meat or can only have their meat/milk used after a lengthy 'withdrawal' period.
I know NZ has (or at least had) an even stricter policy for organic meat, as I spent a few months working on an organic beef and sheep farm a few years back. I don't have any knowledge of organic regulations in other countries, except that overseas produce sold in the UK as organic must abide by UK regulations.
