Gastric Dilation-Volvulus Syndrome (GDVs) in Dogs
GDVs is a gastrointestinal syndrome wherein the stomach is seen to flip (usually 180-360° clockwise) on its axis, causing internal damage through ischaemia, inflammation and possibly infection. It comprises three parts:
- acute gastric dilation,
- acute gastric dilation-volvulus (GDV) and
- chronic gastric volvulus.
GDVs is most commonly seen in large or giant dogs with deep chests (Great Danes, GSDs, Irish setters and standard poodles are over represented in GDV studies). A high thoracic depth to width ratio is commonly noted in affected dogs. Other risk factors include:
- diet,
- gastric volume and position - yep, stomachs vary between dogs,
- gastric ligament laxity - what’s holding the stomach in place?
- control of eructation (burping) and pyloric canal function - or anything else that will result in gas build-up.
The onset of symptoms is usually acute and can occur after a large meal or a bout of exercise (swallowing air is thought to contribute to the flip). Symptoms aren’t the most specific but the dog’s signalment should certainly ensure that GDV is on your DDx (differential diagnoses list). Symptoms can include:
- agitation, restlessness, lethargy;
- progressive abdominal distention (tympany) - this will lead to increasing pain as the internal pressure builds/ischaemia begins;
- retching, unproductive vomiting;
- cardiovascular (CV) compromise - hypovolaemic shock, etc.
Local effects of GDV mainly affect the stomach and spleen - this is due to a compromise in blood supply to both organs. As the stomach and spleen are connected by the gastrosplenic ligament, when the stomach moves it tends to bring the spleen with it. This movement of the spleen can result in avulsion of small gastric branches of the splenic artery and therefore, may lead to ischaemia or necrosis of the stomach (especially the fundic region). Similarly, as tension increases within the stomach, compression of intramural vessels may occur.
Systemic effects of GCV are mainly due to CV compromise (i.e. the mechanical obstruction of blood flow through the caudal vena cava and hepatic portal vein). Any vascular obstruction will result in decreased venous return to the heart, a subsequent decrease in cardiac output and hence hypovolaemia. For this reason, the GDV dog must be managed with fluid therapy in order to return the circulating levels to normal.
Fluids are the main immediate management of the GDV dog but analgesia should ideally be offered as soon as the dog is stable(ish). Pure opioids (morphine or methadone) are good to relieve pain but also calm an animal for exam. Short-term analgesia (e.g. fentanyl) is useful in some cases. If the resources are available, and echocardiogram (ECG) should be performed in order to monitor CV system. Many dogs with GDV will develop arrhythmias - treatment for this should be withheld until all other CV symptoms are stabilised as sometimes GDV-related arrhythmias will resolve themselves. Unfortunately however, approximately 40-50% of dogs who present with GDV will develop a permanent arrhythmia. These are usually ventricular and are caused by myocardial injury.
Once the dog is stable, actually resolving the GDV becomes priority. The first stage in this process is to try and decompress the stomach. Using an orogastric tube is the preferred way to do this but if a tube cannot be passed, percutaneous gastrocentesis can be performed using a large gauge needle. It’s important to measure an orogastric tube prior to beginning the procedure: the tube should extend from the nostril to the last rib. This is necessary to ensure that iatrogenic damage isn’t caused by a too-long tube. The aim of decompression is to release some of the pressure in an effort to prevent further ischaemia.
Regardless of the success of compression, surgery is indicated for every GDV patient. If a GDV dog isn’t operated on, they will almost certainly die (either due to complications or further GDV episodes). The aims of surgery are to fully decompress and reposition the stomach, assess the viability of any affected organs, remove any devitalised tissue and perform a gastropexy (fixing the stomach to the abdominal wall or diaphragm to prevent another GDV in the future). Some things to note regarding GDV surgery:
- A distended stomach will be noticeable from size and can be further seen to be a GDV if it is covered by an omental leaf (this is due to the stomach entering the omental bursa during flipping).
- Additional decompression can be accomplished by an intraoperative gastrocentesis or with a guided orogastric tube.
- Gastric necrosis is reported in ~10-40% of GDV dogs. The stomach should be checked thoroughly for ischaemia and necrosis and if any is present, a gastrectomy should be performed to remove those foci.
- It’s advised to wait ~10 mins after repositioning the stomach as bruising caused by the torsion can often be incorrectly identified as necrosis.
- The most common site for necrosis is along the greater curvature at the junction between the fundus and the gastric body.
- A gastric resection is always a possibility in the case that the stomach isn’t completely viable. If there is too much necrosis then euthanasia may be advised.
- The spleen should also be thoroughly checked for damage, especially the splenic vessels.
- A gastropexy should always be performed. A gastropexy aims to fix the most mobile part of the stomach (pylorus) to the right abdominal wall.
Post-operative care is important after all surgery. The temperature, respiration and cardiac capacities are very important indicators of any problems. Fluid therapy should be continued and post-operative analgesia is essential (NSAIDs should be avoided). If there were no major complications, the dog can be offered food and water the day after surgery. It’s advised that the patient is admitted for a further 3-5 days for monitoring. In addition to the persistent cardiac arrhythmias mentioned earlier, other complications include aspiration pneumonia, abnormal gastric motility, necrosis or perforation. When treated successfully, there is a good to excellent prognosis for GDV dogs.
If you have any questions, additions or corrections, please let me know! This is my first real vetty post so all feedback is appreciated. :)
