SUPPURATION. 35 



is still circumscribed ; however, it is not called an abscess, but 

 " purulent effusion." 



Abscesses are occasionally found to exist without the usual 

 signs of inflammation ; they are then called " cold abscesses ; " 

 and when slowly formed, chronic or old abscesses. 



Abscesses are divided into acute and chronic. 



ACUTE ABSCESS. 



Symptoms. — Symptoms of inflammation precede the sup- 

 puration ; there is heat, pain, and swelling in the part, with 

 more or less symptomatic fever; for a time the pain increases, 

 and changes to a throbbing character. The swelling becomes 

 harder from increased exudation, and when the abscess is deeply 

 situated, tliere is some oedema of the surrounding areolar tissue. 

 Concomitant with these symptoms, a tendency to rigor or 

 shivering may be observed by the staring coat, or actual rigors 

 of a severe character may occur. 



In the centre of the swelling pus is formed, and around this 

 a layer of condensed plastic lymph, being the boundary or 

 cyst of the abscess. The quantity of pus increases, and b}^ its 

 presence causes the absorption of the boundary of the abscess, 

 more particularly of that portion nearest to the free surfaces of 

 the body, generally the skin. The swelling becomes soft in the 

 middle, but continues hard at the base, and oedematous at a 

 greater distance. The next chans^e is the elevation of the centre 

 into a prominent hairless spot. This is called the pointing of 

 the abscess. 



In general, some time before the abscess points, fluctuation 

 is discoverable, particularly if it is superficially situated ; but 

 if deep-seated, and where the superimposed structures are still 

 tense and thick, the quantity of pus but scanty, the perception 

 of fluid is obscure; it becomes, however, more and more dis- 

 tinct as the tissues external to it become thinner. 



A noticeable feature in the pointing of an abscess in the 

 lower animals is the removal of the hairs, these falling off and 

 leaving a bare spot on the most prominent part of the swelling. 

 This is accounted for by the absorption of the skin and destruc- 

 tion of the hair follicles, which take place before the abscess 

 finally bursts. When the collection of matter is small, or 



