Hairy shaker disease brings financial setback

Press, 14 February 1986, Page 12

Hairy shaker disease brings financial setback

One Canterbury farming family’s encounter with hairy shaker disease in their sheep brought financial adversity out of the purchase of another farm for a son.

The family, which, does not want to be identified, lost an estimated $15,000 to $20,000 in the year of purchase of the new farm and the effects of the disease, -on stock health and financially, are still being felt. Hairy shaker disease is a viral disease of sheep which has been present in New Zealand since the 1950 s and is widespread in the South Island. The highly infectious disease poses no danger to adult sheep, which apparently become immune. But a first encounter with the virus for pregnant ewes can result in abortion, or the birth of small weak lambs, perhaps with an abnormally coarse straight birthcoat and a body tremor or shake.

Diseased lambs often have stunted appearance with short limbs, a short head and domed skull. They will , not thrive and are particularly susceptible to parasites and pneumonia.

Most sheep farmers will recognise the signs for the very small number of such lambs which are born in every flock and usually dispatched immediately with a blow to the head. But an incidence of 40

per cent of lambs from two-tooth ewes, or a drop in anticipated flock lambing percentage of over 20 per cent, would be classified as an animal health disaster by most farmers.

Such an outbreak was recorded four years ago on a Canterbury farm and a reduced effect from the disease is still apparent within the same Coopworth flock today. Without being aware of the danger he was running, the farmer mixed the two flocks from his own farm and the new farm he was buying late in the 1982 tupping period and ran them together from then on.

By so doing, he was exposing his own ewes, which must have had little previous contact with the virus, to ewes which had a high disease status and probably were dropping a few hairy shaker lambs every year. Such an incidence of hairy shaker lambs may have been considered normal to the former owner and not worth even commenting about. But it proved important because of the flock mixing at the wrong time of the sheep breeding year.

“My advisers said I could mix the flocks,” said the farmer, “because not a lot was really known about the disease.” The virus attacked the foetuses in the home flock, particularly those carried by two-tooth ewes, and the result was an abortion “storm" followed by the birth of hundreds of hairy shaker lambs. During lambing the farmer brought home ,up to six hairy shakers a day to be nursed and fed and many more were either left dead in the paddocks or with their mothers.

"In the first year we tried to save them all,” said the farmer’s wife, “but later it became obvious that they were never going to do well and they died in far greater numbers than normal before and after weaning." “Now a bad hairy shaker gets the chop immediately/’the farmer

said, “because it is just not worth the effort to try and raise them.” His comment shows that it was not just a one-year problem. The incidence of hairy shaker lambs has now settled at about 20 per cent among the two-tooths and 5 per cent in the older ewes.

This is still much more than most farmers will experience and more than was found in a slink lamb survey conducted over five years recently by Dr Bob Gumbrell, of the M.A.F. Animal Health Laboratory at Lincoln. His survey identified 72 hairy shaker lambs from 18 farms over the five years and nine farms out of 20 were shown by blood tests to have sheep with a positive test to the virus, or to be carriers. With advice from veterinarians and M.A.F. researchers from Lincoln and Wallaceville, the farmer has continued to mix his ewe lambs and two-tooths with older ewes well before tupping to get a thorough exposure to the virus. He has also considered hogget mating to try and get rid of the diseased lambs early in the productive life of a ewe.

“At the moment we cannot really answer why the incidence is still so high,” he said. He suspects that many farmers might have a 10 per cent level among their lambs from two-tooths but do not really consider it significant, perhaps because the symptons are only slight or “sub-clinical.” “Now that I know what to look for, I can see hairy shakers in other flocks as I drive around,” he said.

However, such an impression is not really supported by Dr Gumbrell’s survey. The reverse of a "nondisclosure” syndrome among farmers with hairy shaker lambs has in fact been concerning the staff of the M.A.F.’s Invermay Animal Health Laboratory, near-Dunedin. Several reports of

"geep” or “shoats” have been investigated. But instead of being crosses between sheep and goats, these are held by the M.A.F. staff to be lambs afflicted with hairy shaker disease. Dr Marjorie Orr of Invermay has advised farmers to mix two-tooths and any bought-in ewes with the main mob of breeding ewes for at least six weeks before tupping. The longer and closer contact the better. An alternative is to run a few hairy shaker lambs with the ewe lambs, ewe hoggets or bought-in lambs for as long as possible. These lambs should be taken out before tupping in case they transmit the virus to any pregnant sheep which have not acquired immunity. ' Two researchers from the Wallaceville research station, Drs Rod Oliver and Brian Schroder, are using the Canterbury farm with the bad outbreak to study the spread of the disease and ways of controlling it. The two-tooths have been split into three mobs — a control with no special treatment, a mob with hairy shaker lambs mixed prior to tupping' and one which receives a new vaccine from the United States. The 150 two-tooths involved have been bled and tested for the virus and this will be repeated each month. It is too early to publicise any results. Having been through the hoops 1 with this disease, the farmer is quite willing for the Wallaceville wallahs to do their stuff. “I want to be co-opera-tive otherwise no-one will find the answers we all need,” he said. ,