Sheep Scab. 
85 
contracted by association with affected sheep, probably the 
symptoms of the disease will not be manifest for two or three 
weeks or more after contact. 
It is possible, where scab has been acquired by rubbing 
on objects which have served the purpose for a scabby sheep, 
that considerable numbers of the parasites may be transferred 
to the healthy sheep, which, in such case, might show signs 
of irritation earlier. Experimentally, they have occurred in 
fourteen days after infestation. It must be borne in mind 
that keds, ticks, and lice are extremely common in sheep, and 
frequently co-exist with the scab parasite. It is probable that 
these other parasites play an important part in the spread of 
scab, by causing scab-free sheep to rub against objects on which 
scabby sheep have been rubbing. “ One scabby sheep infects 
a flock ” is an old saying rendered none the less true by the 
above fact. While scab may perhaps be usually spread in a 
flock by rubbing on inanimate objects, it does not invalidate 
the postulate, that scab is usually introduced into a flock by 
the admission of affected sheep. 
Sheep scab, as shown by the returns of the Board of 
Agriculture, occurs more in winter than summer, a circum- 
stance probably accounted for by the fact that dipping is 
usually practised in the early summer. It is more common 
in mountainous districts where sheep are scattered, do not 
congregate frequently, or receive comparatively little individual 
attention. 
Prevention . — The Sheep Scab Order of 1905 imposes on 
the owner of sheep affected with scab, or suspected of being so 
affected, the duty of giving notice of the fact to the nearest 
police constable. Measures to be adopted in flocks in which 
scab exists must provide for the destruction of mature parasites 
and their eggs. One thorough dipping in any effective dip 
will probably kill all living parasites, but the eggs may remain 
a source of danger, so that a second dipping should be given in 
from seven to fourteen days after the first, which will probably 
effect a cure by destroying any acari developed from the eggs. 
In rare instances, however, usually dependent on inefficient 
material or inrperfect operation, some doubt may remain, when 
a third dipping should be resorted to. The process of “ salving,” 
i.e., the application to the skin of some greasy parasiticide, such 
as mercurial ointment, is still preferred by some flockmasters 
as being a more certain means of cure than dipping. That 
salving with mercurial ointment may prove an effectual form 
of treatment is beyond doubt. There is some danger to the 
life of the sheep connected with its use, but the experienced 
hand who is able to dress the whole of the skin with a very 
small quantity does not run many risks. In old-standing cases it 
