BBC News website at the Royal Welsh Show
The disease is unusual in goats, says the assembly government
Cases of bovine TB have been found in goats in Carmarthenshire.
The Welsh Assembly Government confirmed the outbreak and said it knew of a similar case in England which is understood to be linked.
The disease in goats is "unusual", and animal health officials are checking to see if it has spread to other herds.
The latest TB cases came as some MPs and AMs urged the assembly government to halt plans to cull badgers, which are known to spread TB to cattle.
Farmers' groups believe a cull of badgers would stem a rise in cases.
Of the outbreak in goats, Brian Walters, vice-president of the Farmers' Union of Wales (FUW), said the news was a worrying development, while a goat milk producer in Carmarthenshire voiced her concerns.
An assembly government spokeswoman said: "We are aware of an outbreak of bovine TB in goats in England and Wales that includes a case in Carmarthenshire."
Defra's executive agency Animal Health are responsible for management of the outbreak, as well as possible tracings to other herds.
"Animal Health are keeping officials in the TB team at the Welsh Assembly Government fully informed of developments with this outbreak," said the spokeswoman.
"A letter will shortly be published in the veterinary record summarising the current situation and advising veterinary practitioners of the need to consider bovine TB when investigating goats with clinical signs suggestive of the disease.
"The Goat Veterinary Society (GVS) has also circulated information to its members."
The spokeswoman added that such outbreaks were "unusual" and, as with all infections, they were treated seriously.
It is not known where in Carmarthenshire the outbreak has occurred.
The GVS on its website said the disease was first found following a post mortem examination of a goat in Wales a few weeks ago.
"The herd in question was in the process of being sold up due to retirement at the time the discovery was made," writes the society's secretary Nick Clayton to members.
"And many of the goats from that herd went to two other herds, from both of which stock had been sold on quite widely."
The FUW's Mr Walters said it was a "worrying development".
"It's another reservoir of TB that could affect the whole industry," he said.
"The question is why and how did the goats pick it up?"
Loraine Makowski-Heaton, a goat farmer from near Llandeilo, Carmarthenshire, said people in the industry were concerned about the outbreak.
But she said the majority of goat milk producers, including her, pasteurised their milk.