CHAPTER XIII. 

 ABSCESS. 



DEFINITION. — An abscess is a collection of pus that 

 hollows out a cavity in the tissues by destroying and expand- 

 ing them. The word "abscess" may also be applied to deposr 

 its of pus in the natural cavities, i.e., in the sinuses, in the 

 guttural pouches, etc. The term "collection" is, however, a 

 m>)re suitable designation for such accumulations. 



CLASSIFICATION. — The study of abscesses requires 

 numerous classifications. We distinguish hot (or acute) ab- 

 scesses when the evolution is rapid, and cold (or chronic) 

 abscesses when the progress is slow. These are again 

 subdivided into superficial, deep, idiopathic and symp- 

 tomatic. Multiple suppurating foci following a fixed 

 collection of pus are called metastatic abscesses. Crit- 

 ical abscesses are those which supervene as the sequel of a 

 grave malady. Their appearance is followed by a marked 

 improvement in the patient's condition. Closely related to 

 this variety are sudden abscesses, which occur chiefly among 

 debilitated subjects and appear without any signs of inflam- 

 mation. Pneumonia in the horse, terminating unfavorably, is 

 often marked by an outburst of abscesses of this character. 

 As to their contents, abscesses may be classified according 

 to the special products they contain, into biliary, stercora- 

 ceous, urinary, milky, etc. 



ETIOLOGY. — The dominating causes of abscesses are 

 either predisposing or exciting: 



I. Predisposing causes. — (a) Species. — All writers con- 

 cur in admitting that certain species suppurate more readily 

 than others. The horse, for example, is usually regarded 



345 



