Collection of Pus in the Nasal Sinuses. 91 



The horse is thrown and made fast with the diseased side of the 

 head uppermost. A point is then selected on a line drawn between 

 the centres of the two eyeballs and an inch to one side the median 

 line of the forehead ; the hair is closely removed with the scissors, 

 and a semi-circular flap of skin over an inch in diameter is dis- 

 sected from the bone and turned back toward the poll. The tre- 

 phine is next applied on the bone and a circular portion, having 

 been cut through, is pulled out by the forceps, when the imprison- 

 ed pus will commonly ooze from the opening. A second point is 

 chosen just above the lower end of the bony ridge of the upper 

 jaw already referred to and opposite the third molar tooth, count- 

 ing from before ; the hair is removed as before, a flap of the skin 

 raised upward and backward and the bone trephined to open the 

 second sinuse. The point of election for this orifice is more im- 

 portant than that of the first. If it is too near the eye the lower 

 part of the sinus, which is separated from the upper by an imper- 

 forate bony plate, is not opened and may continue to keep up the 

 discharge from the nose. If on the contrary it is made too low 

 down, the lower sinuse only is opened and the upper being im- 

 perfectly washed out from the wound in the forehead will keep up 

 the discharge. Either then this plate must be struck with the 

 trephine or it must be afterward perforated to secure a favorable 

 result. The prob introduced by the wound in the forehead should 

 further appear at the lower orifice. 



The cavities are to be washed out first with clear tepid water, 

 and thereafter daily with an astringent solution such as that used 

 for injecting the nose. If the discharge does not escape freely by 

 the lower orifice its exit may be facilitated by drawing a tape 

 through the sinuses, from the upper to the lower, and retaining it 

 there by a knot on each end. 



Marked f cetor of the wound will usually indicate necrosis at the 

 edge of the wound, and demands the use of bone forceps or chisel 

 to remove the offending bone. 



A cure is affected by the restoration of the membrane to its nat- 

 ural state, or in other cases by the filling up and obliteration of 

 the cavity by granulation. 



