DISEASES OF SHEEP. 345 



that are not well understood, but are believed to consist of some 

 unfavorable qualities of the water and the herbage. It is known 

 by English and Scotch shepherds as the louping ill, or hydro- 

 rachitis; from which is derived the common term rickets- applied 

 to young animals affected by weakness of the hind limbs See 

 fig. 25. 



The common form is similar to inflammation of the brain 

 in its etfects on the animal, and similar symptoms are perceived 

 These are paroxysms of convulsed movements; a high temper- 

 turea; a rapid pulse and breathing. These finally end in paralysis 



of the hind parts, so tiiat the 

 young animals, which are mostly 

 subject to this disorder, drag their 

 hind limbs along without ability 

 to move them. There is a great 

 tenderness, along the spine, and 

 the animal shrinks when the 

 spine is pressed. If the patient 

 is able to stand is is only in a 

 staggering way, and it rests its 

 FIG. 23. Myelitis. head against any support within 



reach. 



These symptoms are greatly increased in the enzootic form. 

 Lambs are frequently born diseased, and are paralyzed from their 

 birth. Others are attacked later, and after a time up to a year 

 and a half old. The old sheep are rarely subject to the disease. 

 The lamb in some instances has the head and neck drawn to one 

 side, others exhibit spasmodic movements by which they seem to 

 be endeavoring to leap, using, however, only their forelegs. From 

 this symptom the local name of louping or leaping ill or disease is 

 given. Hut mostly the lamb lies half reclining on the ground and 

 drags its hind parts along as shown in the illustration, fig. 25. 



The' causes seem to include among others generally applicable 

 to this class of diseases, a certain distinct unwholesome quality 

 in the herbage, thought to be due to the geological character of 

 the soil, by which excessive succulence is given to it, leading 

 to chronic indigestion and mal-nutrition. This is believed to be 

 the case, for the reason that the disease may prevail extensively 

 and severely in some locality which may be distinctly separated 

 from adjoining lands of a different geological origin. It is well 

 known that a limestone soil is productive of increased fertility 

 and luxuriance of the pastures, or of grown feeding crops, and we 

 know that any seriously unbalanced character of the food does 

 affect the nervous system more or less disastrously. 



This is all the more to be considered as being well founded, 

 although we have no satisfactory certainty of it, by the special 

 accompanying symptoms which are noticed at the outset of the 

 disease. As for instance, there is a depraved appetite, and a vora- 

 cious desire for coarse innutritions food; and stones, sand, de- 

 composed matters, rotten wood, and such like substances are 

 greedily devoured and swallowed. The grass is not bitten, 



