PARASITES AND PARASITIC DISEASES 
OF SHEEP. 
Maurice C. HAty, Zoological Division. 
CONTENTS. 
Page Page. 
Liability of sheep to parasitic dis- Internal parasites—Continued. 
COS ee eee. ee See eee 3 Bladderworms—Continued. ‘i 
Important preventive measures——__ a ithe cid parasite —-—--=—2—— 27 
mrxternal parasites 2. .2--9 -_ "= 5 Mhe hydatid =e 2 31 
Nd Ce ee wae ye GE 5 EY ees tee Ne eee 33 
Mbessheep), tiek=——- 2 = = —= 8 The common liver fluke__—- 33 
Nheep-scab” mite--2 2 —.. = 10 The large liver fluke_____- 36 
Other external parasites__——-~- 15 Rounadworms=——= == = 72 == ee 37 
Miterual parasites [=~ = -_ Les 16 The stomach worm=—--———— 38 
ETHIE ODOOS = te eos eee Ae 17 The nodular worm_—=--———- 42 
Grub tinethe head === 25> = 17 The sheep hookworm--—-_-~ ~~ 45 
MamewOnuiS, = aes 2 ee Ee 20 The thread-necked  stron- 
PRC IN ONLEZIAS = ee 20 eylesp =o. Sa See AT 
The fringed tapeworm —___ 22 hes whipworma = === == 48 
Bago ery Ormise a  S 24 The thread lungworm__-___ 50 
The thin-necked  bladder- The hair lungworm_____ = Dill 
WO IN ese a wes oe a a ee 8 24 Other internal parasites___-~_-_ 53 
Sheep measles___-____--__ 26 
LIABILITY OF SHEEP TO PARASITIC DISEASES. 
HEEP are very liable to attack by parasites, probably suffering 
more severely from this cause than any other kind of livestock. 
The importance of parasites and parasitic diseases of sheep is the 
more evident because of the fact that sheep are but little subject to 
serious bacterial plagues or virus diseases. They are practically 
immune from tuberculosis, which is one of the serious conditions in 
cattle and swine, and among sheep there is nothing comparable to 
the devastating outbreaks of hog cholera among swine. Occasion- 
ally a virulent strain of the bacillus producing lip-and-leg ulcer will 
spread under favorable conditions and necessitate the treatment of 
entire flocks, or individual sheep will die of pneumonia or other 
bacterial diseases, but the steady loss of sheep, mutton, and wool 
from disease in this country is due mostly to parasites. 
The damage from parasites is greatest as a rule among lambs 
and young animals. The young tissues seem less resistant and 
more intolerant of injury and the more sensitive nervous system 
breaks down more quickly under the influence of parasitic injury 
and poisoning from the excretions and secretions of parasites. It 
also seems to be fairly well established that in general young animals 
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