372 



HEALTH AND DISEASE 



KERATOMA— HORN TUMOUR 



Fig. 393. — Keratoma or Horn Tumour 



Notch or groove in the pedal bone resulting from pressure 

 of Keratoma. 



A tumour composed of 

 liorn sometimes forms on the 

 internal face of the hoof, from 

 whicli it projects inwards, and 

 l)y continued pressure imbeds 

 itself in the substance of the 

 l)odal or foot bone, some of 

 wliich it causes to be ab- 

 sorljed. These growths may 

 be elongated, ovoid, or cone- 

 shaped. They mostly occur at 

 the toe, but, rarely, also appear 

 at the coronet, from which they 

 extend downwards towards 

 the lower border of the foot. 

 Keratoma is produced by an abnormal growth of horn from the laminae 

 or papillae of the vascular tissues by which the hoof is secreted. 



Causes. — These 

 growths have their origin 

 in some injury or irrita- 

 tion.of the horn-secreting 

 structures. A blow or 

 tread on the coronet may 

 be the exciting cause, 

 but more commonly it 

 would seem to have some 

 connection with injury 

 done to the toe, which 

 is generally believed to 

 be inflicted by too much 



force being used in ham- 

 the toe 

 )y a nail 



mering down 

 clip. Injury 

 driven too near the quick 

 may also lie the starting- 

 point, or it may follow a 

 crack in the hoof How- 

 ever produced, there is evidently a chronic state of congestion excited in 

 the horn-forming structures at the seat of the morbid 2:rowth. 



Fig. 394. — Keratoma or Horn Tumour 

 Transverse section of foot, showing Keratoma («) in situ. 



