Veterinary experts in northern Germany have confirmed that a cat found dead on the island of Ruegen died from the highly pathogenic Asian strain of the H5N1 bird flu virus.
They believe the cat contracted the disease by eating infected birds.
The disease was identified in wild birds on Ruegen last month.
The experts at the Friedrich Loeffler Institute, advise the government on animal diseases, and say they are not surprised by the discovery and do not regard it as a reason to take any extra measures to curb the disease.
The World Health Organisation supports this view and says the appearance of the virus in a cat is unlikely to increase the risk to humans of the disease.
To date the H5N1 bird flu virus has killed 94 people since late 2003 and made under 200 sick, but it remains predominantly a disease of birds.
It is contracted by handling sick or dead birds infected with the virus.
The deaths from the virus have been in South East Asia and Turkey.
However some experts consider that cat-to-human transmission cannot be dismissed.
In response the German authorities have ordered all domestic cats be kept indoors and dogs kept on a leash in areas hit by bird flu.
So far the virus has been identified in five German states, and the area where the diseased birds were found has been placed under a three-kilometre cordon.
Birds in Austria, France, Greece, Hungary, Italy, Slovakia, Slovenia, Turkey and South East Asia have been affected by the virus.
In the UK people are being advised to avoid poultry markets even though no cases have been reported there as yet in poultry or wild birds.