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AgVetLink: Number 63, August 2007

Oestradiol

The European Commission has recently adopted a proposal for a total ban on the use of oestradiol 17ß to treat food-producing animals. Oestradiol 17ß and its esters were previously permitted for the treatment of foetus maceration/ mummification and pyometra in cattle (for animal welfare reasons).

A scientific review of these uses concluded they had a poor technical basis and were superseded by more effective therapies. Oestradiol esters are no longer registered for these indications in New Zealand – registration was withdrawn by the registrant in 2001.

Previously the use of oestradiol 17ß and its esters in oestrus synchronisation (cattle, horses, sheep and goats) was banned, effective October 2006, by EU Directive 2003/74. The oestrus synchronisation ban did not, in NZFSA’s view, have an immediate impact on third countries as oestradiol was still authorised within the EU for the treatment of foetus maceration/mummification and pyometra in food-producing animals. With the new proposal mentioned above, the situation has changed.

Reassessment required

This new information has prompted a notice issued under the Animal Products Act which effectively prevents the use of oestradiol in cattle, sheep, goats, deer and ostriches and the sale of products that are labelled for use in these species. As a consequence a reassessment is required, in accordance with section 29 of the ACVM Act, of the registrations of all products containing oestradiol other than those approved for companion animals or managed by the conditions applied to hormone growth promotants. The registrations that are being reassessed are injectable and capsule formulations approved for use in cattle to manage anoestrus and oestrus synchronisation. As there are no other registered indications for these products, the reassessment effectively results in the cancellation of the registrations.

Alternative programmes

The removal of these registrations has no impact on the management of conditions that affect the welfare of cattle. There are alternative programmes using GnRH and prostaglandins in conjunction with progesterone-releasing devices or as stand alone treatments. The indications are the market will have adequate supplies of these drugs for the coming season.