The breeding programmes of an estimated 2000 of Australia's top thoroughbred broodmares are in disarray as the equine influenza scare bites deeper.
Two quarantine facilities are locked down after an imported stallion returned a positive test to the highly contagious virus.
A total of 79 horses, including a significant number of shuttle stallions from other parts of the world, are now stranded in quarantine for at least a month.
The affected stallion is thought to have come from Japan, where authorities are also working to contain an outbreak.
The two facilities are at Eastern Creek, near Sydney, which is holding the affected stallion, along with 51 other horses. The Victorian facility at Spotswood, with 27, is also locked down because some of the horses from the other facility has been in contact during transit.
The Federal Minister Agriculture Minister has said up to 25 shuttle stallions were affected.
It is understood Sheik Mohammed's Darley Stud has been particularly hard hit, with 17 of its team unable to be released. The stallions include Elusive Quality and Exceed And Excel.
Nine on Coolmore Stud's stallion roster are also affected. These include Encosta De Lago, Rock of Gibraltar, Choisir, Danehill Dancer and Holy Roman Emperor.
Meanwhile, vigilance has spread well beyond the walls of the quarantine facilities. Tests are being conducted on a horse held near Randwick, Sydney, which is showing signs of respiratory infection, but it is not expected to test positive for equine flu.
Meanwhile, Japanese thoroughbred horse racing will resume this weekend, with several race meetings scheduled.
Race meetings on August 18 and 19 had been cancelled to help contain the spread.
More on equine flu: News, Q&A and contacts