ARCHIVE FILE
See the original document
INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
NEOPLASMS IN EWES
Apparent Association with Radical Mules Operation
L. A. W. MACTIER, B.V.Sc., Inspector of Stock, Moree.
Flystrike in sheep has been attacked over many years and from many angles, but perhaps no single line of attack has been so effective in prevention as the Mules operation; the "radical" variation of which includes the removal of the wool-bearing skin of the tail Length of tail, either short, medium or long, also had an appreciable effect in regulating the degree of strike in ewes. However, the fact that the radical operation may become too radical, and tails too short, has been stressed by events in this District. At the time, the practice on the station property in question was to leave a very short tail on the lambs; and to carry out a radical Mulesing by making two cuts on each side of the bare area and then completely stripping the tail of skin. The end result was that the majority of the tails disappeared entirely and an uninterrupted square bare area was obtained. On closer examination, though, it could be seen that in a considerable number of cases the vulva, due to excessive stretching, was partly open.
Another factor with probably a most important bearing on the ultimate ill-effects of the radical treatment was the fact that Trefoil Dermatitis was particularly severe on the property concerned in 1948, occurred again in the next year, and following the floods of 1950 was appreciable in 1951 and 1952, with some occurrence again in 1953. During the bad outbreak of 1948 Lamp Black was not obtainable, and attempt was made to supply the necessary "pigmentation" by dusting heads and tails with Red Ochre. As at that time the bare areas of the Mulesed ewes all were very red and inflamed, the red ochre treatment no doubt served to mask the onset of real trouble.
By shearing in May, 1953, on this property there were thirty-four (34) 5-year-old and twenty-nine (29) 7-year-old ewes affected with Neoplasms of the vulva. By 13/10/53, of 6,581 cwes of these ages, 112 had been destroyed and skinned as the growths had become obvious, while 86 were missing; presumed affected and dead.
In June, 1953, the writer forwarded to Glenfield specimens from one of two ewes inspected and found to have a neoplasm which appeared to have originated on the inner aspect of the vulva. The subsequent report from the Director of Veterinary Research stated:
"The specimen consisted of preserved genitalia from a ewe. Attached to the medial side of the vulval lip was a growth about 2 inches in diameter. This was very fibrous: with a dark, roughened exterior. Microscopic examination of sections from this showed the growth was a neoplasm of epithelial type having characteristics intermediate between a papilloma and an epithelioma'".
On 12/10/53, specimens were obtained from two ewes showing what appeared to be an early stage of the neoplastic development. Glenfield advised, however, that histological examination of this tissue showed no evidence of neoplastic growth.
Since 1953 the station practice has been modified to the extent that a contractor has been employed to carry out Mulesing. Only one cut is made on each side before stripping the tail; while a "medium" tail has replaced the very short variety of earlier years.
As no further growths, neoplastic or otherwise, have appeared in the ewes since the change in method of Mulesing and the tail length, it appears that the growths were due to the radical operation, combined with the very short tail, which caused such stretching of the bare area that the vulva was pulled open; admitting light and air to the interior. In addition, there was the continued irritation of the bare area by the occurrence of Trefoil Dermatitis; with attacks by mosquitoes during the summer probably providing a further aggravating factor.