Pet Surgery Topics

Gastric dilatation-volvulus (GDV), often referred to as canine bloat,  dog bloat, or gastric torsion, is a serious life-threatening condition in  dogs. Gastric dilatation-volvulus is the process whereby the stomach turns on itself and fills with air resulting in an overdistention of the stomach and a decrease in the blood flow to the stomach wall. Left untreated, most animals  will die from gastric dilatation-volvulus.

Pathophysiology

Gastric Dilatation-Volvulus

Gastic dilatation-volvulus is suspected to initiate with the stomach rotating on itself. The stomach can rotate anywhere from 90 degrees to 360  degrees, but often rotates between 220-270 degrees. When this occurs, the esophagus which goes from the mouth to the stomach gets twisted and the pylorus which is where the stomach empties into the intestines gets twisted, thus closing off any exit from the stomach.  The stomach then becomes distended with air. The air is thought to come from the dog swallowing air (aerophagia) and not being able to eructate (belch) and from carbon dioxide formation within the stomach secondary to fermentation  nd changes in the metabolism in the cells that make up the stomach wall. This air is essentially trapped in the stomach and the stomach continues to dilate as more of the gas gets trapped. This results in the stomach turning into a large balloon within the abdomen.

The dilated stomach puts pressure on the major vessels within the abdomen, the caudal vena cava and the portal vein, which reduces the amount of blood that is returning to the heart. This leads to signs of circulatory shock and damage to the heart due to lack of blood flow. This damage to the heart can manifest as arrhythmias which are commonly seen with GDV.

When the stomach twists and dilates with air, the vessels that provide blood supply to the stomach wall become compromised and lead to the cells that make up the stomach wall dying. If enough of the cells die, the stomach wall will become necrotic and ultimately perforate.

The spleen of the dog is intimately associated with the stomach and when the stomach rotates, the spleen also rotates. This can lead to tearing of the vessels that attach the spleen to the stomach, or lead to compromise in the blood supply to the spleen resulting in the spleen also dying.

Epidemiology

Gastric dilatation-volvulus primarily occurs in large, deep-chested dogs. Classic breeds that get GDV are Great Danes, Weimaraners, Saint Bernards, German Shepherd dogs, Irish Setters, Gordon Setters, and Doberman Pinschers. We also see it in many other large and giant breed dogs as well as some medium and small dogs such as Shar-Peis and Basset Hounds. It tends to occur in middle-aged to older dogs but can occur at any age.

The cause of GVD is unknown. There have been many studies that suggest exercise after eating a large meal can predispose dogs to GDV. Feeding one large meal, feeding soy-based or cereal-based dry dog food, stress, feeding from a raised food bowl, rapid eating, and having a fearful temperament have all been found to be predisposing factors in studies. One factor that greatly increases the chance of having a GDV is having a parent with a history of GDV. It has been recommended to not breeding dogs that have a parent with a history of GDV because of this.

Recommendations for owners with high risk breeds currently are to feed several small meals a day rather than one large meal, avoid stress during feeding and anything that causes dogs to eat rapidly, restrict exercise before and after meals, do not use elevated feeding, and don’t breed dogs with a family history of GDV.

Clinical Signs

Nonproductive retching, hypersalivation, and restlessness are common signs seen with canine bloat. Owners may also see progressive distention of the abdomen and a tight or tympanic feel to the abdomen. Sometimes, owners just find the dog recumbent and depressed with a distended abdomen.

Diagnosis

Radiograph of GDV

The diagnosis of gastric dilatation-volvulus is made with radiographs. Taking a radiograph with the dog laying on its right side shows a classic “reverse-C” or “double bubble” sign which is the gas filled pylorus sitting above the gas filled fundus of the stomach.

Other tests that are commonly run include bloodwork, plasma lactate concentration, and in some older dogs chest radiographs. Bloodwork is usually run to have a baseline for how the kidneys, liver, electrolytes, red blood cell levels, and platelet levels are before surgery. In most cases, the bloodwork is normal. Plasma lactate concentration has been found to be prognostic with higher levels being associated with gastric necrosis and a poor prognosis. Chest radiographs are commonly taken in older dogs with GDV to make sure there are no signs of metastatic disease to the lungs which would suggest some form of cancer in the body that has already spread. This is not always done and is strictly so owners know before deciding about surgery whether their older dog has any other life-threatening disease.

Treatment

Initial treatment of gastric torsion in dogs is fluid resuscitation to improve blood flow then decompression of the stomach. On presentation, the first step is placing one or more intravenous catheters and providing large volumes of fluids to help with the circulatory shock. Other types of fluids such as hetastarch (synthetic protein fluid) and hypertonic saline (very concentrated fluid) are sometimes used to accomplish the same thing.

Gastric decompression can be performed by passing an orogastric tube (tube through the mouth into the stomach) or by trocharization of the stomach. Trocharization is a procedure where a large needle or catheter is passed sterilely through the abdominal wall into the stomach to allow the air to come out of the stomach. This is a temporary way of decompressing the stomach, allowing the dog to become more stable and reduce the circulatory shock being caused by the overly distended stomach impeding blood flow from returning to the heart. Passing an orogastric tube can be  one in an awake dog but it is painful and most dogs resist the procedure. Also, because the stomach has twisted, the esaphogus is also twisted and sometime the tube is very difficult to get into the stomach.

Surgery is always indicated for treating gastric dilatation-volvulus. Decompressing the stomach through trocharization or passing of an orogastric tube is a temporary way of stabilizing the dog but surgery is always necessary to make sure the stomach is repositioned appropriately and to pexy the stomach so it cannot twist again. Surgery should be performed as soon as possible after the dog has been stabilized.

Once the dog is anesthetized, an orogastric tube is passed if it wasn’t passed initially. With the tube in the stomach, the stomach is usually lavaged to remove any food or gastric secretions that are within the stomach. This is not completely necessary but makes the stomach easier to manage during surgery when it is not full of a lot of food.

At surgery, a majority of dogs will still have the stomach twisted once the abdomen is opened. On occasion, the act of decompressing allows the stomach to move back into its normal position. Repositioning the stomach involves rotating it in a counter-clockwise direction putting the pylorus  back on the right side of the abdomen and the fundus on the left. Once the stomach is repositioned, the stomach wall is assessed for any areas of  necrosis. Necrotic areas appear purple to black in color and often the wall appears thinner than expected. If any area is questionable, it is recommended to remove the affected area. The spleen is also assessed during surgery. It is not uncommon for the vessels that attach the spleen to the stomach to tear when the stomach twisted. If blood supply to the spleen appears to be damaged then the spleen needs to be removed.

Laparoscopic View Of A Gastropexy

Once the stomach is in normal position and the viability of the stomach wall accessed, a gastropexy is performed to attach the antral region (right side of the stomach) to the right abdominal wall. This greatly reduces the chance of the dog being able to have the stomach twist again.  There are a few methods for performing the gastropexy and which type that is performed is dependent on surgeon’s preference. In all cases, the main objective is making a permanent attachment of the stomach to the abdominal wall. With a gastropexy, the chance of a dog having a torsion again is under 10%. Without a gastropexy, the recurrence rate is around 80%.

Having to resect a portion of the stomach because the wall appears dead carries a much higher chance of mortatlity. In studies, dogs that required a gastric resection had a 60% mortality rate.

Aftercare

After surgery, dogs need to be monitored closely for arrhythmias of the heart which are very common. Arrhythmias can start immediately after surgery or within 12 hours of surgery and can last for 48-72 hours after surgery. If the arrhythmias are severe and clinically affecting the dog they may require treatment with anti-arrhythmics.

Another condition that can be seen after surgery is disseminated intravascular coagulation (DIC). Disseminated intravascular coagulation is a disease where the dog uses up all of its factors for clotting is blood due to the severe trauma that the GDV caused the body and results in an inability to clot the blood. This leads to spontaneous bleeding which can be life-threatening. DIC is rare but can commonly be seen if part of the stomach had to be resected. Treatment for DIC involves aggressive treatment with plasma and fluids.

Most dogs recover well from surgery and can start eating within 12-24 hours after surgery. If there are no arrhythmias and the dog otherwise appears comfortable and able to eat, it can often go home within 24-48 hours after surgery. Owners are instructed to minimize activity to
leash walks for the first two weeks while the abdominal incision heals. It is also recommended to feed the dogs smaller, more frequent meals after surgery. Two weeks after surgery, the dog can return to normal activity if it has recovered well.

Although going to surgery and performing a gastropexy reduces the chance of a dog twisting its stomach again, there is a chance that the dog can continue to have the stomach dilate with air. This is a rare occurrence but can be seen. These dogs represent in the future with a distended, tympanic abdomen but the stomach is in the normal position. Treatment involves passing an orogastric tube to relieve the gas within the stomach but surgery is not necessary since the stomach has not twisted.  Why these dogs continue to have the stomach dilate with air is often never figured out.

Nowadays, prophylactic gastropexies are commonly being advocated in high risk, deep chested breeds. Often when one of these breeds is being spayed or neutered, or if an abdominal surgery is necessary for some other reason like to remove a foreign body from the intestines, a gastropexy is also recommended. For patients that are having the gastropexy performed during a spay or neuter, use of a laparoscope to assist in performing the procedure reduces the amount that the abdomen needs to be opened.