^56 OPERATIONS ON THE EESPIEATOEY APPABATUS. 



This rapid summary of the anatomy of the parotid region will 

 sufficiently indicate the dangers which the surgeon is Hkely to 

 encounter at successive steps of the operation, and especially if 

 he duly considers the location of the occipito-hyoideus, which must 

 be reached before the puncture can be made, and again, the pecu- 

 liar course followed by the posterior auricular artery as it emerges 

 from the parotid to reach its destination. 



Hyovertebrotomy is indicated in all cases of repletion of the 

 guttural pouches resulting from a purulent collection and main- 

 tained by a process of chronic inflammation. It is principally 

 when horses have become liable to be attacked with strangles that 

 these purulent collections are formed. They are marked by an 

 increase of size in the pouches, gradually augmenting with the 

 continued formation of the pus, and interfering more and more 

 with deglutition and respiration, sometimes assuming such pro- 

 portions as even to threaten suffocation. Attacks of pharyngitis 

 or laryngitis, or catarrh of the anterior chambers of the respira- 

 tory apparatus and nasal cavities, or sinuses, are at times noticed 

 in connection with this affection. 



To revert to the anatomical arrangement of the parts : The 

 guttural pouches, opening into the cavity of the pharynx by a 

 narrow slit, are situated on the lateral surface, and thus allow any 

 collection of pus they may contain to flow without interruption 

 into the pharynx,and hence into the other nasal cavities. We 

 have here an explanation of the fact that a discharge from the nose 

 in any one of a variety of affections, such as suppuration of the 

 guttm-al pouches, pharyngitis, laryngitis, catarrh, and also the dis- 

 charge of glanders, may aU possess different characteristics, and 

 each exhibit a different aspect, and therefore demand a different 

 diagnosis and require different treatment. 



The discharge from the guttural pouches is whitish, glairy, more 

 or less mixed with mucosities, inodorous, non-adhesive to the wing 

 of the nose, and intermittent, being marked during mastication 

 or deglutition, and especially while swallowing liquids — in all form- 

 ing an assemblage of characteristics which should be sufficient to 

 distinguish the affection from aU others. There is, besides this, a 

 negative point, in the absence of chancres, which with the distinct 

 nature and peculiarity of the discharge, and the characters so 

 typical of the maxillary lymphatic glands in that disease, will 

 largely aid in determining the difference between the two affections. 



