Lesson 94: Pathogenesis of GDV in dogs

What is Gastric Dilatation Volvulus?

A life-threatening disorder characterized by abnormal twisting of the stomach on its mesenteric axis, with subsequent gastric gas accumulation and distention.

What is the common name used for Gastric Dilatation Volvulus?

Bloat or Gastric Torsion.

How does Simple Gastric Dilatation differ from GDV?

Simple Gastric Dilatation involves only the distention of the stomach and can sometimes resolve on its own, whereas GDV involves a gas-filled stomach twisting upon itself.

What happens if simple bloat is not corrected?

It can lead to Gastric Dilatation Volvulus.

What makes GDV a life-threatening condition?

It must be corrected immediately.

What is the first step in the overview of GDV pathogenesis?

Gas accumulation in the stomach.

What is the step that follows stomach rotation in GDV pathogenesis?

Obstruction of blood flow.

What is an intrinsic factor in GDV pathogenesis?

An internal characteristic of an animal that increases its likelihood of a disease or condition developing.

Name two large, deep-chested dog breeds predisposed to GDV.

Great Danes, German Shepherds, Doberman Pinschers, Weimaraner, or Standard Poodles.

How does body conformation increase GDV risk?

Dogs with a deep and narrow thoracic cavity (high Thoracic Depth-to-Width Ratio) increase the risk of stomach torsion.

What age group of dogs has a higher risk for GDV?

Middle-aged to older dogs.

What suggests a hereditary component to GDV?

Family history of GDV.

How does sex potentially influence GDV risk?

Some studies suggest males may be at a slightly higher risk than females.

What history of GI abnormality increases GDV risk?

A history of splenic torsion or gastrointestinal surgeries.

What temperament type of dogs is more at risk for GDV?

Easily stressed or anxious dogs.

What is an extrinsic factor in GDV pathogenesis?

An external or environmental factor that increases the likelihood of a disease or condition developing.

How do feeding practices influence GDV risk?

Eating one large meal per day instead of multiple smaller meals.

What characteristic of food or eating habits increases GDV risk?

Rapid eating, swallowing air (aerophagia), or consuming large kibble pieces.

What specific dry food characteristic is listed as an extrinsic factor?

Dry foods with oils or fats listed within the first 4 ingredients.

Name an environmental factor that can increase nervous behavior and GDV risk.

Stress or anxiety, such as boarding, travel, or changes in routine.

When is vigorous exercise a risk factor for GDV?

Immediately before or after eating.

What happens to the stomach during GDV due to gas accumulation and twisting?

It rotates on its axis, leading to displacement of the stomach and spleen.

What specific structures are mechanically obstructed by the twisting stomach?

Local blood vessels, particularly those supplying the stomach and spleen.

What does increased tension in the stomach walls cause?

A drop in the gastric perfusion pressure.

What condition results from blood being unable to drain properly due to obstruction in the stomach walls?

Venous congestion.

What further contributes to the avulsion of the gastrosplenic ligament?

The displacement of the stomach and spleen.

What can result from the avulsion of the gastrosplenic ligament?

Hemorrhage.

What happens to blood flow within the stomach walls due to obstruction, leading to clot formation?

Blood flow slows down and thickens.

What type of infarction can result from clot formation (thrombosis) in the GDV process?

Splenic infarction.

What condition results when blood vessels within the stomach wall collapse?

Ischemia in the gastric wall.

What are the potential outcomes if gastric wall ischemia is left untreated?

Necrosis and perforation of the stomach wall, leading to sepsis and shock.

What is the significant cardiovascular consequence of GDV caused by decreased venous return to the heart?

Hypovolemic state.

What results from decreased cardiac output during GDV due to organ hypoxia?

Tissue damage and death.

What type of heart rhythm abnormality can result from decreased myocardial perfusion and increased inflammatory mediators?

Cardiac arrhythmias, specifically VPCs.

What causes severe reduction in total thoracic volume during GDV?

Gastric dilatation and increased intra-abdominal pressure.

How does gastric dilatation affect the diaphragm and lung volume?

It prevents the caudal movement of the diaphragm and reduces lung volume, resulting in poor ventilation.

What systemic condition occurs in GDV due to the release of catecholamines?

Systemic hypotension.

What compensatory action occurs due to systemic hypotension in GDV?

Compensatory tachycardia to maintain blood circulation.

What consequence results from increased myocardial oxygen demand in GDV?

Myocardial ischemia.

What is the respiratory compensatory mechanism for restricted lung expansion and reduced tidal volume in GDV?

Tachypnea.

What specific area of the stomach is susceptible to ischemic necrosis due to decreased perfusion?

The fundus.

What is the final consequence of ischemic necrosis in the GI system related to GDV?

Necrosis and perforations, potentially leading to septic peritonitis.

Why is the spleen commonly affected by GDV?

Due to its close relationship with the stomach.

What happens to the spleen due to GDV?

The spleen becomes congested.

What happens to the short gastric arteries because of splenic torsion?

They are avulsed.

What coagulation dysfunction can occur in GDV that puts the patient at risk of thrombosis?

Disseminated Intravascular Coagulation (DIC) in the early hypercoagulable state.

What risk is present in the subsequent hypocoagulable state of GDV-related DIC?

Hemorrhage.

What causes the loss of movement of intestinal contents in GDV?

Intestinal effects due to systemic circulation issues.

What are two effects on the intestine caused by systemic circulation issues in GDV?

Dysbiosis and Sequestration of fluids and protein loss.

What major blood vessels are mechanically obstructed in GDV, causing decreased venous return to the heart?

Caudal vena cava and hepatic vein.

What leads to reduced tissue perfusion as systemic circulation worsens in GDV?

Decreased cardiac output.

What metabolic imbalance is indicated by increased lactic acid due to low oxygen in GDV?

Hyperlactatemia.

What is oliguria?

Low urine output.

What renal indicator in GDV suggests kidney failure?

Oliguria to anuria (no urine production).

What type of injury occurs after the stomach or spleen is surgically repositioned?

Reperfusion Injury.

What is released when the stomach is surgically repositioned, leading to reperfusion injury?

Reactive oxygen species (ROS).

Name two consequences of reperfusion injury in GDV.

Endothelial damage, DIC (Disseminated Intravascular Coagulation), or SIRS (Systemic Inflammatory Response Syndrome).

How long is close monitoring critical following decompression due to the risk of life-threatening complications?

At least 24-48 hours.

Name two early signs of GDV.

Restlessness or pacing, Panting, Retching and/or Vomiting (often non-productive), Hypersalivation, Abdominal Pain, or Distention of the abdomen (Mild to moderate).

Name two progressive signs of GDV (signs of cardiovascular compromise).

Increased Heart Rate (Tachycardia), Weak Pulses, Dark Red Mucous Membranes, or Depressed Mentation.

Name two severe/late clinical signs of GDV (signs of multisystemic failure).

Hypothermia, Coma, Collapse, Severe Abdominal Distention, White or Blue Mucous Membranes, or Cardiac Arrhythmias.

What sign of GDV is often non-productive?

Retching and/or Vomiting.

What is one severe consequence that can occur due to compromised circulation in GDV?

Other organs are at risk of dying.

What diagnostic test can show metabolic disturbances in a GDV patient?

Blood Analysis (CBC, Serum Biochemistry, Serum Lactate).

What specific blood value helps determine the severity of low oxygen in GDV?

Serum Lactate.

When is radiography performed on a GDV patient?

Only when the patient is stable.

What is the key feature used radiographically to differentiate gastric dilation from gastric volvulus?

Radiographic determination of the location of the pylorus.

Where does volvulus usually displace the pylorus?

Dorsally and to the left.

What radiographic finding suggests compartmentalization of the stomach due to volvulus?

A shelf-like partition of soft tissue.

What is the primary therapeutic goal for GDV regarding circulation?

Restore and support circulation.

What is the goal related to the stomach volume in GDV treatment?

Decompression of the Stomach.

What are two methods of gastric decompression/deflation in GDV treatment?

Stomach Tube or Percutaneous Trocarisation.

What emergency surgery is performed for GDV?

Gastropexy (various techniques).

Name two types of Gastropexy techniques mentioned.

Incisional, Belt Loop, Circumcostal, or Laparoscopic.

What must be established therapeutically before correction?

Whether volvulus or simple dilation is present.

What is the overall survival rate if GDV is diagnosed and treated quickly?

98% survival rate.

What complication leads to a guarded prognosis and a survival rate of 66% in GDV cases?

Gastric necrosis.

Name two conditions that give the poorest prognosis for GDV.

Evidence of DIC, sepsis, heart arrhythmias, and severe damage and/or perforation of the stomach.

What feeding recommendation is given to prevent GDV?

Feed several small meals a day rather than one large meal.

What action should be restricted before and after meals to prevent GDV?

Exercise.

What practice related to feeding bowls should be avoided to prevent GDV?

Do not use an elevated food bowl.

What procedure is recommended for high-risk GDV breeds as a preventative measure?

Prophylactic gastropexy.

What genetic factor is advised against in breeding practices to prevent GDV?

Do not breed dogs with a first degree relative that has a history of GDV.

What is the segment of the intestine that invaginates called?

Intussusceptum.

What is the segment of the intestine that receives the invaginated segment called?

Intussuscipiens.

What is the general term for the proximal segment of the GI tract (closest to the mouth)?

Orad.

What is the general term for the distal segment of the GI tract (closest to the rectum)?

Aborad.

How are intussusceptions named?

According to the segments involved.

Name one site besides Ileocecal or Ileocolic where intussusception can occur.

Jejunojejunal or Jejunoileal.

What GI condition is a known predisposing factor for intussusception?

Any enteritis.

What happens during the Invagination stage of intussusception pathogenesis?

Irritation occurs, leading to hyperperistalsis.

In intussusception pathogenesis, what becomes entrapped within the intussuscipiens, causing compression of blood vessels?

The Mesentery.

What is the term for the systemic consequence of intestinal necrosis and bacterial translocation in intussusception?

Sepsis and peritonitis.

What characterizes the stool in chronic or partial intussusception cases?

Soft or ribbon-like stool.

What physical exam finding suggests intussusception?

Sausage-shaped mass (enlarged bowel segment).

What surgical action is taken if the intestines are viable during intussusception surgery?

Manual Reduction.

What organs of the GI tract can be affected by Torsion or Volvulus?

Stomach, Spleen, Small or Large Intestines.

What is the definition of Torsion?

Twisting of a segment of the small intestine or stomach along its longitudinal axis (lengthwise).

Torsion of the stomach is typically characterized by a rotation of what degree?

Less than 180 degrees (clockwise rotation).

Volvulus typically implies a twisting of what degree?

More than 180 degrees.