OF VETERINARY MEDICINE. 229 



lighter. This condition is a rarifying process and it is called 

 osteoporosis. The Haversian spaces are much increased in size 

 and tl>e bone is made porous. Osteoporosis may be observed 

 both in spongy and compact bone. 



Osteosclerosis is analogous to cicatricial formation of the 

 fibrous connective tissue and is a result of inflammation of bone. 

 It may occur without any apparent cause in senility in the diploe 

 of the skull, causing it to become dense. It always occurs about 

 carious and necrotic areas, constituting one of the chief means by 

 which the sequestrum is surrounded by new dense bony tissue. 

 Osteosclerotic exostoses of ivory-like hardness are called ebur- 

 nations. Such bone is much heavier than normal. 



Periosititis may be acute or chronic. In the acute form the 

 morbid changes are found first in the periosteum itself, which 

 becomes swollen, hyperaemic and more or less infiltrated with 

 serum. In some cases infection takes place and suppuration oc- 

 curs. The pus collects between the periosteum and the bone, 

 elevating the membrane — (subperiosteal abscess). This fre- 

 quently brings about a molecular destruction of the surface of 

 the bone, causing the mineral structure to crumble away, and 

 leaving softened and excavated areas, while particles of the dis- 

 integrated bone lie free in the surrounding tissue. To this mole- 

 cular death and destruction of bone the name caries is given. 



Caries usually occurs in cancellated bone. It is often seen in 

 fistulous withers, caused by the pus burroughing down to the 

 bone. The depressed surface has a peculiar velvety feel. It is 

 also seen in poll-evil and may involve the axis or even the den- 

 tata in poll-evil. Foot Rot in sheep is often followed by caries 

 of the digits. In treating such a condition, open up the sinuses 

 or diseased parts and scrape out all the diseased portions and a 

 little of the healthy part as well. Treat antiseptically and the 

 bone will granulate the same as other tissues. 



The acute forms terminate either in recovery without dam- 

 age to the bone, when the abscesses are absorbed or rupture ex- 

 ternally ; or in caries or necrosis, with subsequent chronic dis- 

 turbances induced by the process of bone-destruction, that may 

 continue during the entire life of the animal or require surgical 

 interference. 



