DISEASES OF THE EYE AND ITS APPENDAGES. 365 



and cause periorbital abscess, or necrosis may result from the presence 

 of a splinter of bone or the excessive destruction of bone. In all 

 cases of fracture the animal should be taken out of the herd and 

 kept by itself until the injured part heals. 



NECROSIS or THE BONY OKBIT. 



As the result of fracture of the margin of the orbit a part of the 

 injured bone may become necrosed (dead), and periostitis and perior- 

 bital abscess will follow as a consequence. The discovery of this dis- 

 ease will at first resemble abscess, but on making an examination with 

 a probe after the abscess is open we will find the bone rough and 

 brittle at the point of disease. The discharge will have a peculiar 

 fetid odor, and is often mixed with blood. 



Treatment. — The affected bone must be laid bare and all diseased 

 portions removed by scraping or, if necessary, with saw or chisel, 

 disregarding the extent of the injury or the size of the wound neces- 

 sary to be inflicted. A large portion of the bony orbit may be re- 

 moved without serious danger to the eye, provided the eyeball itself 

 has not been previously affected by the disease or involved in the 

 original injury. 



TUMORS OF THE ORBIT. 



A fungous tumor of the eyeball or orbit occasionally appears, which 

 is designated fungus hu&inModes. This may arise without any appre- 

 ciable cause, or as the result of a wound. It frequently commences 

 within the eyeball as a small, red mass, eventually bursts through, and 

 pushes its way outside of the orbit as a large, dark-red mass, bleed- 

 ing at the slightest touch. It has a peculiar fetid odor, and early in 

 its appearance destroys sight, involving all the contents of the orbit, 

 not infrequently the bony wall itself. 



Unless the tumor is totally removed in its early stage of growth, 

 together with the eyeball, the disease will eventually cause emaciation 

 and death of the animal. The enucleation of the eyeball should not be 

 undertaken by anyone unacquainted with the anatomical structures 

 involved in such an operation. When the operation is performed 

 early enough the result is generally satisfactor\\ 



Bony tumors of the orbit are occasionally present in cattle, the re- 

 sult of bruises, fractures, etc. They may encroach upon the contents 

 of the orbit, causing paralysis of the optic nerve — the condition 

 known as amaurosis — or by pressure upon the posterior surface of the 

 eyeball force it forward, or produce atrophy (shrinking). They may 

 displace the eye in any direction, with or without disturbing vision. 



Fibrous tumors growing within the orbit will produce symptoms 

 similar to those of bony tumors. 



