92 Veterinary Medicine. 



For this the following articles are required : scissors, a knife, 

 forceps, a trephine or circular saw from half to three-fourths of 

 an inch in diameter and a whalebone or metallic probe. 



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 im- 

 prisoned 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, 

 counting 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 sinus. The point of election for this orifice is more 

 important 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 

 imperforate 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 sinus only is opened and the upper being 

 imperfectly 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 favor- 

 able result. The probe 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 foetor 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 effected by the restoration of the membrane to its 

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

 of the cavity by granulation. 



