Peritonitis

Chapter 76 Peritonitis



Stephen J. Birchard


Peritonitis is a common problem in small animals. Primary peritonitis can occur in cats (feline infectious peritonitis; see Chapter 10), but other forms of peritonitis in dogs and cats are usually secondary to other diseases or injuries. Advances in the diagnosis and treatment of peritonitis have lowered mortality rates. However, peritonitis continues to be a serious and life-threatening condition that requires aggressive management.


In this chapter, the general topic of peritonitis is discussed. For more detailed information on the treatment of the specific causes of peritonitis, refer to appropriate chapters.



ANATOMY


The peritoneum is a serous membrane composed of mesothelial cells. It consists of the parietal peritoneum that lines the abdominal cavity and the visceral peritoneum that covers the abdominal viscera. The peritoneum has tremendous surface area (i.e., 50-100% of body surface area). The peritoneal cavity is closed in the male but open in the female through the reproductive tract. A small amount of fluid that lubricates the abdominal viscera is produced by the peritoneum.



ETIOLOGY




Viral


Feline infectious peritonitis is an example of primary peritonitis (see Chapter 10).



Bacterial



Gastrointestinal Perforation or Leakage




Key Point


Loss of bowel wall integrity accounts for the majority of cases of bacterial peritonitis in dogs and cats.


Leakage of bowel contents allows release of bacteria, predominantly anaerobes and gram-negative aerobes. Fluid and ingesta may also leak if gross bowel wall disruption occurs, resulting in a complex interaction of bacterial, chemical, and foreign body factors in the pathogenesis of peritonitis.


Bowel leakage can occur by a variety of mechanisms:



• Perforation—The bowel can be penetrated by external objects such as gunshot or a sharp object.

• Neoplasia or granuloma—Leakage from a necrotiz-ing gastrointestinal (GI) neoplasm (carcinoma, lymphoma) or granuloma can occur.

• Corticosteroids—Colonic perforation can occur secondary to the administration of high doses of corticosteroids in animals with spinal compression.

• Foreign bodies—Sharp intestinal or linear foreign bodies frequently cause perforation (see Chapter 69). Also, intraluminal pressure on the intestinal wall by a foreign body can eventually lead to ischemic necrosis and leakage.

• Blunt trauma—Devitalization of the bowel can occur secondary to tearing of the mesenteric blood supply.

• Strangulation—Any process causing obstruction of the intestinal blood supply causes loss of mucosal integrity and eventually full-thickness necrosis (see Chapter 69). Loss of the so-called mucosal barrier can result in translocation of bacteria and/or endotoxins into the peritoneal cavity.

• Dehiscence—Unsatisfactory healing of a GI incision may result in leakage through the wound and subsequent peritonitis.


Pyometra


Bacterial infection of the uterus can lead to peritonitis by leakage through the fallopian tubes or overt rupture of a pus-filled uterus (see Chapter 90).



Prostatic or Liver Abscess


Abscesses of the prostate gland (see Chapter 84) or liver (see Chapter 71) may leak bacteria to the peritoneal cavity spontaneously or iatrogenically during surgical exploration.



Surgical Contamination


A breakdown in aseptic technique can result in contamination of the peritoneal cavity and peritonitis.



Chemical



Urinary Tract


Leakage of urine from any part of the urinary tract can cause chemical peritonitis.



• Causes of urinary tract disruption include trauma (blunt or penetrating), bladder or urethral rupture due to obstruction, and traumatic catheterization (see Chapters 77, 79, and 81). Urinary tract disruption due to blunt trauma frequently is associated with pelvic and sacral fractures or luxations.

• Bacterial peritonitis can complicate the chemical peritonitis from urine leakage if urinary tract infection was present before the leakage occurred.


Biliary Tract



• Trauma to the biliary tract can cause leakage of bile due to rupture of the gallbladder or one of the bile ducts.

• Spontaneous leakage of bile can occur with rupture of the gallbladder due to diseases like necrotizing cholecystitis and mucocele. Bacterial peritonitis may also complicate this situation.

• Bile is irritating to the peritoneum. However, several days may elapse before an affected animal is presented for clinical signs of peritonitis and biliary disease.


Key Point


A clinical study in dogs and cats found a grave prognosis for animals with combined bacterial and bile peritonitis.



Gastrointestinal Tract



• Gastric fluid contains hydrochloric acid and therefore is very irritating to the peritoneum. Proximal intestinal fluid contains bile and pancreatic enzymes that may cause a combination of chemical and bacterial peritonitis.

• Leakage of gastric fluid may occur due to trauma or any of the other causes of tissue breakdown listed under “Gastrointestinal Perforation or Leakage.”

• Gastric fluid may leak secondary to perforating ulcers or necrotizing gastric neoplasms (see Chapter 67).

• Tissue necrosis secondary to gastric dilatation-volvulus can cause leakage of gastric contents.

• Gastric contents are not always sterile. Bacterial contamination associated with leakage of ingesta can complicate the peritonitis and result in a combination of chemical and septic peritonitis.


Chyle



• Disruption of the mesenteric lymphatics, lymph nodes, or cisterna chyli can cause leakage of chyle into the peritoneal cavity.

• Neoplasia or other diseases causing erosion or obstruction of the lymphatics are more likely causes than disruption due to trauma.

• Chyle is irritating to the peritoneum, although in some animals it is reabsorbed by the abdominal lymphatics.


Pancreatitis



• Leakage of pancreatic enzymes and various chemical mediators of inflammation from the inflamed pancreas causes peritonitis (see Chapter 73).

• Local peritonitis is very common with pancreatitis. Severe, necrotizing pancreatitis or pancreatic abscess may cause generalized peritonitis.


Traumatic


Penetrating trauma that involves the peritoneal cavity, such as a gunshot or knife wound, will cause peritonitis even if the viscera are not injured.



Iatrogenic (Surgical)



• Varying degrees of peritonitis result from surgi-cal manipulation of the peritoneum or abdominal structures.

• Analysis of peritoneal fluid after routine abdominal surgery shows increased neutrophils and increased serum lipase concentrations, suggesting pancreatic inflammation.

• Typically, peritonitis from routine visceral manipulation is clinically insignificant. Poor surgical technique, such as rough handling of tissues, allowing tissues to become desiccated, and lack of aseptic technique, can result in more serious peritonitis.


Foreign Body



Sutures



• Implantation of excessive, large, or contaminated sutures can result in focal peritonitis.

• Non-absorbable braided sutures (e.g., Braunamid, B. Braun Melsungen) that are contaminated can cause chronic focal peritonitis and resultant sinus tracts and abscesses.


Key Point


Avoid placing non-absorbable, multifilament sutures in the peritoneal cavity or viscera.



Surgical Sponges



• Failure to remove surgical sponges can result in focal or diffuse peritonitis. Even sponges considered sterile can cause a significant foreign body reaction. Contaminated sponges cause abscesses and possibly severe, septic peritonitis.

• Prevention of this complication is essential.

• Count surgical sponges before and after surgery to be sure that none have been left in the abdomen.

• Use sponges that contain a radiopaque marker to allow diagnosis of a sponge foreign body with abdominal radiography.


Other Foreign Bodies



• Failure to remove surgical instruments can cause a foreign body reaction, irritation of viscera, and strangulation of blood supply to structures.

• Talc used on surgical gloves can cause a foreign body, granulomatous peritoneal reaction. After donning surgical gloves, rinse with sterile saline before opening the peritoneal cavity.

• Bacterial peritonitis is a potential complication of peritoneal dialysis caused by contamination during the procedure or ascending infection via the indwelling dialysis catheter.


DISTRIBUTION AND LETHAL FACTORS




Local Peritonitis



• Local peritonitis is common and usually does not require aggressive surgical management.

• The abdominal structures, such as the omentum and mesentery, are able to “wall off” inflammatory processes and prevent spread to the entire cavity.

• The production of fibrin by the peritoneum is also an important process in confining bacteria and debris to an isolated area of the peritoneal cavity.

• Permanent adhesions can be a sequela of local peritonitis, but they rarely cause a significant clinical problem in dogs and cats.


Diffuse Peritonitis



• Diffuse or generalized peritonitis occurs when the processes of confinement are overwhelmed and the entire cavity is affected.

• Diffuse peritonitis is a serious condition that requires aggressive medical and usually surgical therapy.

• Movement of the diaphragm, intestinal peristalsis, and gravity encourage dissemination of bacteria throughout the peritoneal cavity.

Related posts:

  1. Feline Infectious Peritonitis (Feline Coronavirus)
  2. Borreliosis (Lyme Disease)
  3. Immune-Mediated Dermatoses
  4. Otitis Media and Otitis Interna

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Aug 27, 2016 | Posted by in SMALL ANIMAL | Comments Off on Peritonitis

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