A cat neurologist, Georgina Child, has put down five cats over the past week and treated or consulted with other vets about more than a dozen others suffering from paralysis.

Dr Child, who is based at the University of Sydney's veterinary hospital and the Small Animal Specialist Hospital in North Ryde, said the only factor that linked all the cats was a specialist pet food called Orijen, which is imported through a Canadian company, Champion Petfoods.

"There is a highly suspicious link because this is an uncommon expensive food in this country at the moment, and not sold in supermarkets," Dr Child said. "But all tests that have been done so far haven't given us an answer."

First symptoms included wobbliness or weakness in the animal's hind legs, which could then progress to the front limbs. The condition did not appear to be infectious, Dr Child said, nor typical of a nutritional deficiency.

"Most worrying is that the cats showed no signs [of illness] while on the food," she said. "It seems to be happening weeks or even months later."

The marketing manager of Champion Petfoods, Peter Muhlenfeld, confirmed yesterday the cat deaths had been traced back to Orijen's dry cat food, and the problem appeared to be restricted to Australia.

He said samples sent back by the Australian distributor had a "strange odour". The company is investigating whether irradiation upon entry into Australia was the source of the contamination.

The Oddy family of Dundas has lost two cats in the past week. "They were the children's pets; it's awful," Sarah Oddy said.