NZ to check Canadian cattle for mad cow disease

Fourteen dexter cattle imported from Canada will this week be checked by veterinarians for symptoms of mad cow disease, such as abnormal posture, behavioural changes and lack of co-ordination.

The Ministry of Agriculture and Forestry's acting director animal biosecurity, Carolyn Hini, said the 14 cattle were located on five North Island properties and the inspections would happen this week.

Dexter cattle, which normally grow less than 1m tall, were popular on lifestyle blocks and other small holdings.

Maf is tracing cattle imported from Canada after last week's announcement that BSE (bovine spongiform encephalopathy) was found in an 8-year-old cow killed in January in Alberta, Canada.

Cattle show symptoms of mad cow disease between two and 10 years after being infected, and the average incubation period is about five years.

One possibility is that infected nerve tissue was distributed in livestock feed before meat and bone meal containing such tissue was banned in that country in 1997.

Another is that infection arose spontaneously in the cattle.

Either possibility could mean New Zealand imported infected cattle.

Tracing had shown that two of a group of 16 cattle imported into New Zealand in 1999 had since died of natural causes. Neither directly entered the human food chain - one was buried, the other rendered.

Biosecurity staff have been unable to determine how a study animal imported in 1994 then killed for "failure to perform" was disposed of.

Dr Hini said Maf was still trying to trace other Canadian cattle imported since 1989, which was twice the length of time required under international standards.

Mad cow disease erupted in Britain in 1986.

It is thought to have spread through cow feed made with protein and bone meal from other mammals.

The human form of mad cow disease is Creutzfeldt-Jakob disease, which causes paralysis and death.

Scientists believe humans could develop new variants of Creutzfeldt-Jakob when they eat nerve tissue in meat from infected animals.

- NZPA