INFECTlorS DISKASES. . 581 



rapidl}', and if urged to go faster may sustain a fracture or ha\e a 

 ligament torn from its l)ony attaehments, especially in the lower 

 bones of the leg. An atleeted horse weighing 1,U00 pounds was seen 

 by the writer to fracture the large |>astern bone from rearing during 

 halter exercise. 



The animal becoujes poor in llesli, the coat is rough and luslerless, 

 j.nd the skin tight and harsh, producing a condition termed ''hide- 

 bound," with considerable " tucking up '' of the al)domcn. The horse 

 fchows a short, stilted, choppy gait, which later becomes stiller and 

 more re.stricted, while on standing a positi(m simidating that in 

 founder is assinned, with a noticeable dr(»p to the croup. The animal 

 at this .stage usually lies down and remains recumbent for several 

 days at a time. lied sores frequently arise and fractures are not 

 uncotiuuon in conse<|uence of attempts to arise, which complications, 

 in addition to emaciation, result in death. 



The disease may exist in this manner for variable |>eriods extend- 

 ing from two or three montlis to two years. The t<?rmination of the 

 disease is uncertain at be-st, but is likely to i>e favorable if treatment 

 and a change of feed, water, and location is adopteil in the early 

 stages of the malady. 



LiHion.s. — As has been stated, the bones are the principal tissues 

 involved. The nutrition of the bone is disturbed, as is indicated by 

 the diminished density or rarefacticm of the bony substances, the 

 increase in the size oi- widening of the Haversian canal and the 

 medullary cavity, and the enlargement of the network of spaces in 

 the spongA' tis.sue, the absorptive changes following tlie course of the 

 Haversian system. In this process of ab.sorption there are formed 

 within the sub.stance of the bone areas of erosion, indentatioiLs, or 

 hollow spaces of ii-regular shape. These spaces increa.se in si/.e and 

 become confluent, causing an apjiearance resembling some varieties 

 of coral. The affected bone may be readily incised with a knife, the 

 cut .surface appearing linely porous. This i^orous area is soft, pli- 

 able, and yields easily to the pressure of the finger. It has been 

 shown by chemical analysis that the bone of an osteoj)orotic horse, 

 when compared with that of a nornial horse, shows a reduction in 

 the amotmt of fat. phosphoi-ic acid, lime, and soda, but a slight in- 

 crea.se in organic matter and silicic acid. The bones lose their yel- 

 lowish-white appearance, becoming gray and brittle. The a fleeted 

 1 ones may Im- those of any region or portion of the body, liesides 

 the change already noted in the Ixines of the face, the ends of the 

 long bones, such as the ribs, are involved, and may be sectioned, 

 though not so readily as the facial bones. The bones <if the vertebrir 

 are al.^^o frequently involved, necessitating great care in casting a 

 horse, as the writer has .seen several ca.s(\s of broken backs in cnsting 

 such animals for <)ther oj^erations. The marrow and cancellated 



