Canine bloat or gastric dilatation with or without rotation is the expansion of the stomach with food, air, fluid or any combination. If there is NO rotation and the stomach is just enlarged and stretched but not malpositioned, it is just dilatation. Dilatation alone can often lead to a rotated condition known as Gastric Dilatation – Volvulus. This is a bloated and malpositioned stomach and is a true veterinary medical emergency. This condition has also been called Gastric Torsion.
The condition of GDV is mainly a large, deep chested breed problem thought to be brought on by a large capacity stomach that can stretch and rotate in the upper portion of the abdomen. The origin of the air is aerophagia (swallowing) due to excitement or stress from the initial bloating. The fluid accumulation is from gastric secretion and venous congestion. All of this is predisposed by the size of the chest cavity and the nature of the dog (gulper of food and water). It is also associated with exercise before and after eating. Various other causes in addition to the breed predilection are diet (cereal and soy based dry food), large meals at one time and oil or fat additives, along with stress, body condition, feeding at a raised level and first-degree relative with a history of GDV.
Gastric outflow obstruction occurs as the stomach rotates causing the esophagus (inflow) and pylorus (outflow) to become twisted. The patient is unable to eructate or pass the accumulating air and fluid.
Physiology of Gastric Dilatation and Volvulus
As the stomach begins to dilate from the above causes, it can also begin to rotate within the abdominal cavity in a clockwise fashion. This results in the outflow portion of the stomach, known as the pylorus, moving ventral and then dorsal twisting the stomach like “wringing” a towel with an inflated balloon inside. The rotation can vary from 90 to 360 degrees and the more dramatic the rotation, the more severe the condition. Some dogs will present with what is called a partial rotation. This is usually less dramatic in its clinical presentation and not always an emergency but still may require surgery. The spleen will be affected in GDV as it will also get twisted and often need to be removed at surgery. As the stomach begins to turn, a cascade of pathological events begin to occur: compression of the caudal vena cava and portal vein (blood flow to the heart), reduced cardiac output and myocardial ischemia, shock, perfusion to critical organs is reduced and fatality if not corrected quickly.
As stated before, certain breeds are predisposed to GDV – Great Danes, Irish Setters, German Shepherds, Weimaraners and Doberman pinschers, but also Shar-Peis and Basset Hounds among medium sized breeds. The thoracic depth to width ratio is the strongest correlation to predisposition to bloat. An owner will often notice a distended abdomen, retching, depression, restlessness and hypersalivation. Upon seeing these signs an owner should seek veterinary help immediately.
On presentation to the veterinarian, a distended abdomen is palpated along with an enlarged spleen and signs of shock – poor pulse, pale mucous membranes, painful abdomen, rapid heart rate and restlessness. If this is correlated with the typical breed and history, then GDV is suspected and immediate action is required. Radiographs (x-rays) are taken to determine that the patient is bloated and/or twisted. In any case DECOMPRESSION is urgent and can be done by gastric tube but trocar (large needle) may be needed initially in order to pass the tube. Sedation may be required for both procedures. Radiographically, it is determined if the stomach has rotated into 2 compartments and that surgery is required to correct the condition. It cannot be over emphasized as to the importance of early decompression as a life-saving procedure. Once diagnosed, a decision for surgery should be made and begun immediately. Usually bloodwork, EKG and patient monitoring are begun simultaneously. Various blood value abnormalities can be found and treated accordingly. Shock therapy with intravenous fluids is begun and the patient is prepped for surgery.
In the case of a twisted stomach, once the initial shock and distension have been treated, surgery is indicated as both a life-saving procedure and preventative for the future rotation by performing a gastropexy (tacking of the stomach). Careful anesthesia and monitoring are critical and the patient should be rapidly prepared for surgery. The goal of GDV surgery is to complete any decompression that is needed, derotate the stomach, ascertain stomach viability, assess the condition of the spleen (remove if necessary), and perform a gastropexy to prevent future twisting of the stomach.
The surgery is performed with the patient on his back and a long, high midline incision is made to best expose the upper abdomen. The stomach is emptied of any additional air and fluid and derotated back into its normal position. The greater curvature of the stomach at this point is closely evaluated for bruising and viability. Purple to black areas of the greater curvature of the stomach may indicate to the surgeon necrosis of the wall of the stomach. Partial gastric wall resection may be necessary due to necrosis but prognosis is guarded at this point. In severe cases a decision to not continue and recommend humane euthanasia is a possibility.
The spleen is inspected for ruptured vessels from the twisting and its viability is also assessed. Splenectomy is performed at this time if indicated. If the patient is stable and stomach appears viable a permanent gastropexy is then performed to prevent future rotation of the stomach. The goal of the gastropexy is to prevent stomach rotation but may not prevent future dilatation.
Postoperative Care/Complications and Prognosis
Intense postoperative care in needed in the GDV surgical patient. Intravenous fluids and electrolyte balancing, monitoring of the cardiac status with EKG and blood pressure equipment, observing for gastritis, pancreatitis and continued shock are all critical to the success of the surgery. The first 72 hours postoperatively are the most critical, especially for cardiac stability. Cardiac arrhythmias are very common in the GDV patient and need to be closely monitored and treated accordingly. Peritonitis, coagulation disorders, aspiration pneumonia and cardiac failure are all possible complications. The prognosis for GDV is based on timeliness of the diagnosis and treatment, viability of the stomach wall and effective postoperative care. Fatality rates have been reported as high as 45%. Preoperative plasma lactate values may be a prognostic indicator for survivability although surgical observation of the gastric wall is still paramount. Gastropexy is found to be 90% effective is preventing future twisting.
The urgency of this condition cannot be overemphasized and an owner of a predisposed breed may want to consider a prophylactic gastropexy at an early age to avoid the condition.