- Parasites and Parasitic Diseases of Sheep. 13 
rain rot, shear cuts, sunburn, and inflammation of the sebaceous 
glands; the effects of alkali dust may at times be mistaken for scab. 
Treatment.—The only satisfactory treatment for scab is dipping. 
Hand dressing will not suffice and permits the spread of the disease 
while seeming to cure obviously affected areas. Animals must be 
dipped twice at intervals of 10 to 14 days, preferably 10, in warm 
dip. Ewes, bucks, and lambs should be dipped separately. Sheep 
must be held in the dip not less than two minutes; in the case of 
animals with advanced cases, especially in the fine-wool sheep, they 
should be held three to five minutes the first time, unless the crusts 
and scabs are first broken up and soaked with dip. The lime-sulphur 
dip and the nicotin-and-sulphur dip are the two dips recognized in 
official dipping for scabies. 
Prevention.—Open pasture that has been used by scabby sheep 
should be regarded as dangerous for a month or two, and buildings 
are regarded as suspicious for a year or more. Keep sheep away 
from old bedding grounds and other infected areas. As regards 
buildings, pens, etc., it is advisable to abandon them, burn them, or 
else clean and ieee thoroughly if they are to be need after having 
had scabby sheep in them. Stray sheep should be looked on mth 
suspicion and goats may carry scab mites for long periods. Care 
must be used in purchasing sheep from areas where there has been 
any scab. 
OTHER VARIETIES OF SCAB. 
Head scab and foot scab in sheep are relatively rare diseases caused 
by species of mites different from those causing common scab. The 
same methods of treatment may be used, but head scab may prove 
more difficult to cure and four or five or more dippings, supplemented 
by local applications of remedies, may be necessary. In cases of head 
scab the interval between dippings should be shortened to a week’ or 
even to five days. 
OTHER EXTERNAL PARASITES. 
True ticks occasionally infest sheep, but in this country it is rare 
to find ticks present on sheep and we are fortunately free from ticks 
that habitually infest sheep. Among those that do occur on our 
sheep is the spinose ear tick. This is particularly prevalent in the 
Southwest. Jt enters the external canal of the ear and attaches 
there well below the hair line, sucking blood from the tender skin. 
The ticks enter the ear as 6-legged seed ticks, become engorged, grub- 
like larve, molt to form the 8- leewed as, which is cov od with 
numerous Seal spines, and after anne spent in the ear the nymphs 
4Otobius mégnini (Ornithodoros mégnini). For additional ifokmation see Farmers’ 
Bulletin 980 on “The Spinose Ear Tick and Methods of Treating Infested Animals.” 
