FRACTURES OF THE BONES 329 



ostcum is prcsorvetl. Tho extravasation of blood found in the early 

 stages of a fracture which hes in the surrounding parts does not in any 

 way assist in the actual union, but helps to a certain extent in holding 

 the bones together until the callus is formed. The callus, in the begin- 

 ning, is a spongy mass, especially in bones containing a large quantity of 

 marrow. This gradually changes into a bony cicatrix or callosity. This 

 becomes thinner and denser, lessening in diameter, and finally becomes 

 smooth on its surface, forming what is known as ''final callus." Reab- 

 sorption commences at the same time until the body masses, which 

 are useless after the bone is united, finall}' disappear, l)ut there is always 

 a certain amount of enlargement around the fractured ends of a bone 

 at the point of union. Cracks and fissures undergo the same process. 



Period of the Process of Union in Fractured Bones. — The time required 

 to obtain complete union of a fracture — that is to say, until the animal 

 can use the part without any pain or difficulty — depends largely on the 

 size and position of the bone, the age of the animal, and the amount of 

 use the patient makes of it. According to the observations of the 

 writer and others, in fractures in which the periosteum is not torn, or 

 simple fractures of the large bones containing marrow, the time is from 

 eighteen to twenty-four days in adult healthy animals. Fractures of 

 the ribs unite in from ten to fifteen days; in metacarpal and metatarsal 

 bones, ten to eighteen days. In young animals the process is a few days 

 shorter; in very old animals it is much longer. After the union of the 

 fracture, as a rule, the affected leg is not used with as great freedom as 

 it was before. This is especially noticeable in young animals that are 

 growing. Very often there is a subsequent atrophy and impaired 

 development of the muscles of that part. While this may be due to a 

 certain extent to the inactivity of the muscles, when tied up in the splint, 

 and also to pressure of the dressing, it is often noticed after the dressing 

 is removed, and sometimes for weeks afterward, the animal walks stiff 

 or is even lame; massage of the affected leg is useful. 



Therapeutic Treatment. — In simple fractures the treatment con- 

 sists of returning the broken ends of the bone to their proper anatomical 

 position, and holding them securely in place. 



The bringing together of the fractured ends of the bones must be 

 done as soon as possible, and it is accomplished by pulling or extending 

 them in a longitudinal direction until the fractured ends fit together. In 

 some instances where the tissue is loose they have to be pressed back in • 

 their normal position. The animal should be held by an assistant while 

 the operator manipulates the ends into position. In cases where there 

 is extreme pain and in order to keep the animal from struggling, it is 

 advisable to etherize, or better, give the animal a sulx-utaneous injection 

 of morphine. In such cases as fractures of the metacarpal bones, bones 



