COMMON UNSOUNDNESSES AND VICES 



175 



FISTULOUS WITHERS 



Fistula of the withers is a disease similar to poll-evil, but is 

 located at the withers. It is commonly called "thistlelow." 

 Bruises have been thought to be the cause in many cases. In 

 view of the fact that pus is often present, even when there is no 

 evidence of a previous skin wound, it seems reasonable to believe 



Fig. 49. — Chart showing various un.soundnes.ses and defects: 1, Poll-evil; 

 2, Roman nose; 3, pendulous lip; 4, shoe boil; 5, enlarged knee; 6, founder; 7, 

 splint; 8, windgall; 9, fistulous withers; 10, sway back; 11, droop rum]); 12, 

 rattail; 13, crooked tail; 14, broken hip; 1.5, bog spavin; 10, capped hock; 17, 

 thoroughpin; 18, curb; 19, cocked ankle; 20, enlarged fetlock. (Photograph of 

 model designed by Geo. F. Morris.) 



that the pus organisms must have been brought by the blood. 

 Unless the pus is evacuated it may burrow between the muscles 

 and break out on the shoulder. Fistulse may be very slow in 

 forming. A deep-seated abscess cavity of many months' standing 

 with no external signs of its presence has been found in a horse in 

 the dissecting laboratory. A hot, painful swelling appears on one 



