PARACENTESIS ABDOMINIS. 519 



operation has, at the most, only a symptomatic importance. It 

 ma y> D y relieving pressure on the diaphragm, mitigate difficulty 

 in breathing, but it seldom produces lasting improvement. 



Diagnosis of ascites is seldom difficult where so much fluid is present 

 as to call for puncture. The disease is commonest in dogs, whose 

 abdominal walls allow the viscara to be readily examined. Such 

 an examination may give valuable information as to the cause of 

 dropsy. One often finds chronic changes (tumours, &c.) in the 

 liver, which render exceedingly improbable any lasting benefit 

 from operation. The same is true where the dog suffers from heart 

 disease. In such cases the abdomen often shows unmistakable 

 distension, which is sometimes attended with dyspnoea. When 

 the animal is standing, the wave-like movement of the fluid may 

 be felt by placing the left hand on one side of the abdomen and lightly 

 tapping the other side with the right. This phenomenon, termed 

 " Sucussio Hippocratis," is a reliable symptom of dropsy. 



Tapping the peritoneal sac — a very simple operation — is effected 

 with a trocar of the same size as is employed in puncturing the chest. 

 There being no danger here, as in puncture of the intestine, of infecting 

 the peritoneal cavity from the bowel, and it being easy to disinfect 

 the skin, the operation, when carefully carried out, is quite simple 

 and not likely to give rise to peritonitis. Indeed, in former times, 

 when the principles of strict asepsis were not understood, the operation 

 was usually performed quite successfully without antiseptics. 



The puncture was formerly made through the rectum or vagina, 

 but these points have been abandoned because of the risk of infection, 

 and the operation is now performed either in the neighbourhood of 

 the umbilicus close to the linea alba, or on one side of the abdominal 

 wall, the former being usually selected in small animals. In large 

 animals, which are operated on in the standing position, the side 

 of the abdominal wall is more convenient. In cattle the right 

 side is chosen, so as not to injure the rumen, which lies on the left ; 

 in horses the left side, because the caecum is on the right. The bowels, 

 being partly filled with gas, float on the fluid in the lower portion 

 of the abdominal cavity, which is consequently the point selected 

 for puncture. In large animals the operation is performed as follows : 

 After shaving and disinfecting the point of operation, an incision 

 is made through the skin with a pointed bistoury or lancet to assist 

 the passage of the trocar. Puncture is then effected in the same 

 way as puncture of the thorax. The trocar is carefully disinfected 

 and held with the handle in the operator's palm, whilst the fore- 

 finger, lying on the cannula, limits the distance to which the 



