224 VKTERINARV PATHOLOGY. 



Microscopic. — The needle like crystals of sodium urate, in 

 addition tu more or less detritus from necrosis of the tissue, is 

 characteristic of sections or smears of tissues affected with uratic 

 infiltration. 



Tissue Affected. — Articulations are the usual location of 

 uratic infiltration, especially those in the metatarsal region. The 

 skin and visceral organs may be aiTected. 



Effects. — The accumulation of the urate crystals in the artic- 

 ulatidu, prdduces erosion of the articular surfaces, and thus 

 interferes with movement. Tophi beneath tendons also produce 

 disturbance of mobility. 



KERATOSIS. 



DRFlNrTION. 

 GENERAL DISCUSSION. 

 ETIOLOGY. 



Dessication of .surface epithelium. 



E.vcess of intercellular cement. 

 APPEAL<.-INCE. 



Macroscopic — Horny grozvths. 



Microscopic. 

 TISSUE AFFECTED— Epithelium. 

 EFFECTS. 



Jipithelium becomes cornified thus forming the hard horny 

 hoofs, horns and claws. The conversion of epithelium into horn- 

 like substance (characteristic of the hoof) consists of a dehy- 

 dration of the cells and the production of a glue like material 

 that cements the dessicated cells together. The ergots and 

 chestnuts in the skin of the horse are produced by the accumu- 

 lation cif dessicated cells cemented together. 



The cornified epithelium that characterizes keratosis varies 

 from dried scales to dense horn tissue. 



Pathologic cornification is of rather common occurrence in 

 the domestic animals. The skin covering the carpus of oxen fre- 

 quentlv becomes materiallv thickened and cornified, (jne case 

 having been observed in which the cornified mass accumulated 

 until a projecting horn like structure some ten inches long and 

 six inches in diameter at its base, was present. .\s a general 

 condition it is observed in the skin of animals afifected with ich- 

 thyr)sis. 



Etiology. — Irritation appears to be a causative agent in 

 keratosis. The condition may be a sequel of inflammation and 

 sometimes occurs in scars. Whatever increases dessication of 



