Issues

Diaphragmatic Hernia

• Protrusion of an abdominal organ through an abnormal opening in the diaphragm either as an acquired injury or as a congenital defect.
• Traumatic—most common acquired cause; usually the result of automobile trauma but also any forceful blow; sudden increase of pressure results in an abdominal-thoracic pressure gradient, causing a tear in the diaphragm, usually at a muscular portion.
• Congenital—pleuroperitoneal or peritoneopericardial diaphragmatic hernia (PPDH); may note other congenital defects (e.g., umbilical hernia, cranioventral abdominal wall defects, cryptorchidism, cleft palate,ventricular septal defect, aortic stenosis, and portosystemic shunting).
• Impaired lung expansion—because of lack of lung contact with parietal pleura.
• Intrapulmonary changes (e.g., lung contusion, atelectasis, and capillary permeability changes causing edema)—contribute to poor gas exchange.
• Rib fractures due to trauma—may contribute to hypoventilation because of pain or mechanical (flail chest) factors.
• Myocardial trauma can result in various dysrhythmias—ventricular tachyarrhythmias: most common; seen within 24–72 hours after trauma; difficult to control with conventional treatment; commonly resolve within 5 days.
• Various stages of shock—can cause multiple organ system failure.

 

SIGNALMENT

Dogs and cats.

• Acquired—no breed predilection.
• Congenital (PPDH)—Weimaraners may be predisposed; Maine Coon and other longhaired cats may be overrepresented; can be diagnosed at any age because clinical signs are variable and intermittent; often diagnosed incidentally.
• Young animals are at higher risk for both congenital and traumatic causes.

 

SIGNS

Traumatic

• Can be acute, subacute, or chronic (with no known history of trauma).
• Low-grade respiratory signs or vague history of gastrointestinal problems possible.
• Signs may be progressive.
• Tachypnea and respiratory distress—most common; acutely affected patients often in shock.
• Arrhythmias—may be detected.
• Muffled heart and lung sounds along with intestinal sounds—may be auscultated in the thorax.
• Abdomen—may feel empty on palpation.
• Acute incarceration of bowel or stomach—can cause vomiting, diarrhea, retching, bloating, pain, and acute collapse.

Congenital

• May not have clinical signs or develop clinical signs later in life.
• Referable to the respiratory, cardiac, or gastrointestinal system.
• Difficulty breathing, muffled heart sounds, murmurs, and concurrent ventral abdominal wall defects—most common.
• Signs can be acute from strangulation of incarcerated bowel, liver, or spleen or rapid formation of pleural or pericardial effusion.

 

CAUSES & RISK FACTORS

Traumatic—lack of confinement and exposure to automobiles; any blunt trauma; roaming animals and male dogs at higher risk than others.

 

CBC/BIOCHEMISTRY/URINALYSIS

Non-specific changes due to ischemia or shock may be noted

 

IMAGING

• Standard two-view thoracic and abdominal radiography
• Horizontal beam radiography
• Ultrasonography
• Contrast radiography—upper gastrointestinal series or peritoneography
• CT sometimes needed

 

DIAGNOSTIC PROCEDURES

Thoracentesis for pleural effusion.

 

TREATMENT

TRAUMATIC

• Inpatient—treat shock; improve ventilation and cardiac output; manage concurrent injury; stabilize patient before surgery.
• Surgery—early intervention indicated with persistent hypotension despite adequate fluid therapy, severe respiratory failure from excessive lung compression, severe liver failure secondary to organ entrapment, bowel rupture, or enlarging gas-filled bowel seen on radiographs; if patient cannot be stabilized, surgical repair will not necessarily improve cardiovascular and respiratory status.
• Intrathoracic gastric dilation—requires immediate decompression.

 

CONGENITAL

Surgical repair—perform as early as possible to avoid adhesion formation and organ entrapment.

Stabilize patients before surgery.

 

MEDICATIONS

DRUG(S)

Antiarrhythmic agents—as indicated

 

CONTRAINDICATIONS/POSSIBLE INTERACTIONS

Take care when treating for shock with concurrent severe pulmonary contusion due to the risk for fluid overload; products such as hetastarch may be beneficial.

 

FOLLOW-UP

PATIENT MONITORING

Frequent or continuous electrocardiographic monitoring—advised; evaluate for postoperative arrhythmias.

 

POSSIBLE COMPLICATIONS

• Pneumothorax—may develop from excessive pressure on damaged lung tissue during anesthetic bagging or from failure to remove air from the chest cavity after diaphragmatic closure.
• Postoperative hyperthermia common in cats.
• Pulmonary edema—can develop from excessive fluid administration in the face of low oncotic pressure from blood loss, capillary permeability changes secondary to inflammation in response to pulmonary contusion, or lung reexpansion.

 

EXPECTED COURSE AND PROGNOSIS

Prognosis—always initially guarded; favorable after successful control of shock, elimination of any cardiac arrhythmias, successful surgery, and the lack of reexpansion pulmonary edema. Older cats with traumatic diaphragmatic hernia are less likely to survive surgical repair.

 

MISCELLANEOUS

ASSOCIATED CONDITIONS

Congenital peritoneopericardial diaphragmatic hernias may be associated with other congenital midline defects, such as septal defects, cleft palates, umbilical hernias and abdominal wall defects.

 

ABBREVIATIONS

CT = computed tomography

PPDH = peritoneal pericardial diaphragmatic hernia

 

Visit your veterinarian as early recognition, diagnosis, and treatment are essential.

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