28 Surgical Diseases and Surgery of the Dog 



but usually in the connective tissue. It is the result of inflammation 

 caused by pyogenic bacteria and the toxins which the latter elabo- 

 rate. The bacteria generally find access to the tissues through a 

 lesion of the cutis or a mucous membrane, but may be carried to 

 their ultimate destination by way of the blood or lymph streams. 

 The course of abscess formation is as follows : The provocative fac- 

 tor having gained access to a certain area of tissue, there is first 

 multiplication of the same followed by concentration of leucocytes 

 and other tissue cells. Many of these dying, liquefaction takes place 

 in the center of the inflamed area, but at the outer zone of inflamma- 

 tion a sort of wall of granulation tissue forms, protecting the sur- 

 rounding healthy tissues from the infected area. It is this wall 

 which was formerly regarded as a secreting membrane of the pus 

 and erroneously known as the "pyogenic membrane." When, how- 

 ever, the process is of an acute nature, the germs may multiply so 

 rapidly that the walling in is incomplete, and, carried to surround- 

 ing tissues, more pus may form which must perforce burrow along a 

 course of least resistance, principally through intermuscular spaces 

 and along subcutaneous connective tissue, avoiding in its path joint 

 capsules, bone and fasciae, until, upon reaching a dependent position, 

 it begins to point and finally breaks through the skin or it may invade 

 vital organs and produce grave results. 



Two forms of abscess formation are recognized, viz, "acute" 

 and "cold," according to the rapidity of their development. A cold 

 abscess is ordinarily caused by tubercular infection, and it is gen- 

 erally well encapsulated owing to its chronicity. 



The lesions leading to the production of acute abscesses are of 

 diverse nature. Probably bites by other dogs figure in the majority 

 of cases, while contusions and the lodgment in the tissues of infected 

 foreign bodies either of external traumatic origin or by way of the 

 alimentary tract are frequently responsible. Among some of the 

 rarer forms may be mentioned: lympho-sarcom^tous abscess occur- 

 ing in the neck, abscess of the perineal region proceeding from sup- 

 purating prostate gland, abscess produced by passage of transmi- 

 gratory strongyles as witnessed by Megnin in the mammary region, 

 and actinomycotic abcesses. 



Symptoms and Diagnosis. The symptoms of abscess may be 

 local or both local and general. Superficial abscesses are character- 

 ized by extensive local heat and swelling and but little constitutional 



