Immediate treatment is the most important factor in a favorable prognosis. A delay in treatment greater than six hours or the presence of peritonitis, sepsis, hypotension, or disseminated intravascular coagulation are negative prognostic indicators.

Historically, GDV has held a guarded prognosis. Although "early studies showed mortality rates between 33% and 68% for dogs with GDV," studies from 2007 to 2012 "reported mortality rates between 10% and 26.8%". Mortality rates approach 10% to 40% even with treatment. A study determined that with prompt treatment and good preoperative stabilization of the patient, mortality is significantly lessened to 10% overall (in a referral setting). Negative prognostic indicators following surgical intervention include postoperative cardiac arrhythmia, splenectomy, or splenectomy with partial gastric resection. Interestingly, a longer time from presentation to surgery was associated with a lower mortality, presumably because these dogs had received more complete preoperative fluid resuscitation and were thus better cardiovascularly stabilized prior to the procedure.

As a general rule, GDV is of greatest risk to deep-chested dogs. The five breeds at greatest risk are Great Danes, Weimaraners, St. Bernards, Gordon Setters, and Irish Setters. In fact, the lifetime risk for a Great Dane to develop GDV has been estimated to be close to 37 percent. Standard Poodles are also at risk for this health problem, as are Irish Wolfhound, Doberman Pinschers, Rottweilers, German Shorthaired Pointer, German Shepherds, Rhodesian Ridgebacks. Basset Hounds and Dachshunds have the greatest risk for dogs less than .

Meckel's diverticulum occurs in about 2% of the population. Prevalence in males is 3–5 times higher than in females. Only 2% of cases are symptomatic, which usually presents among children at the age of 2.

Most cases of Meckel's diverticulum are diagnosed when complications manifest or incidentally in unrelated conditions such as laparotomy, laparoscopy or contrast study of the small intestine. Classic presentation in adults includes intestinal obstruction and inflammation of the diverticulum (diverticulitis). Painless rectal bleeding most commonly occurs in toddlers.

Inflammation in the ileal diverticulum has symptoms that mimic appendicitis, therefore its diagnosis is of clinical importance. Detailed knowledge of the pathophysiological properties is essential in dealing with the life-threatening complications of Meckel's diverticulum.

Treatment is surgical, potentially with a laparoscopic resection. In patients with bleeding, strangulation of bowel, bowel perforation or bowel obstruction, treatment involves surgical resection of both the Meckel's diverticulum itself along with the adjacent bowel segment, and this procedure is called a "small bowel resection". In patients without any of the aforementioned complications, treatment involves surgical resection of the Meckel's diverticulum only, and this procedure is called a simple diverticulectomy.

With regards to asymptomatic Meckel's diverticulum, some recommend that a search for Meckel's diverticulum should be conducted in every case of appendectomy/laparotomy done for acute abdomen, and if found, Meckel's diverticulectomy or resection should be performed to avoid secondary complications arising from it.

Gastric volvulus of unknown cause comprises two thirds of cases and is presumably due to abnormal laxity of the gastrosplenic, gastroduodenal, gastrophrenic, and gastrohepatic ligaments. Type 1 gastric volvulus is more common in adults but has been reported in children.

The causes are divided into benign or malignant.

- Benign

- Peptic ulcer disease

- Infections, such as tuberculosis; and infiltrative diseases, such as amyloidosis.

- A rare cause of gastric outlet obstruction is blockage with a gallstone, also termed "Bouveret's syndrome".

- In children congenital pyloric stenosis / congenital hypertrophic pyloric stenosis may be a cause.

- A pancreatic pseudocyst can cause gastric compression.

- Pyloric mucosal diaphragm could be a rare cause.

- Malignant

- Tumours of the stomach, including adenocarcinoma (and its linitis plastica variant), lymphoma, and gastrointestinal stromal tumours

Incidence of hiatal hernias increases with age; approximately 60% of individuals aged 50 or older have a hiatal hernia. Of these, 9% are symptomatic, depending on the competence of the lower esophageal sphincter (LES). 95% of these are "sliding" hiatus hernias, in which the LES protrudes above the diaphragm along with the stomach, and only 5% are the "rolling" type (paraesophageal), in which the LES remains stationary, but the stomach protrudes above the diaphragm.

Hiatus hernia are most common in North America and Western Europe and rare in rural African communities. Some have proposed that insufficient dietary fiber and the use of a high sitting position for defecation may increase the risk.

In a peptic ulcer it is believed to be a result of edema and scarring of the ulcer, followed by healing and fibrosis, which leads to obstruction of the gastroduodenal junction (usually an ulcer in the first part of the duodenum).

The combined type of gastric volvulus is a rare form in which the stomach twists mesentericoaxially and organoaxially. This type of gastric volvulus makes up the remainder of cases and is usually observed in patients with chronic volvulus.

The predisposition to diverticulosis for specific individuals is likely explained by a genetic component, a theory which is supported by studies examining the rates of diverticulosis among twins. The heritability of diverticulosis is estimated to be approximately 40%.

The U.S. National Institutes of Health notes that, although the low-fiber theory of the cause of diverticulosis is the leading theory, it has not yet been proven.

Zenker's diverticulum mainly affects older adults. It has an incidence of 2 per 100,000 per year in the UK, but there is significant geographical variation around the world.

Diverticula may occur in one of the three areas of the esophagus - the pharyngoesophageal, the midesophageal area or the epiphrenic area of esophagus. Zenker's diverticulum is found three times more frequently in men than in women. It occurs posteriorly through the cricopharyngeal muscle in the midline of the neck. Usually seen in people older than 60 years of age.

- Gastric diverticula - "Although usually asymptomatic, they may cause vague epigastric pain. These lesions may be confused radiologically for gastric ulcers or cancers. Endoscopically, they may be confused for paraesophageal hernias."

- Killian-Jamieson diverticulum

- Meckel's diverticulum: a persistent portion of the omphalomesenteric duct present in 2% of the population

- Rokitansky-Aschoff sinuses: in the gallbladder due to chronic cholecystitis

- Traction esophageal diverticulum: due to scarring from mediastinal or pulmonary tuberculosis

- Urethral diverticulum: congenital in males, post-infectious in females

- Zenker's diverticulum: a diverticulum of the mucosa of the pharynx affecting adults

Most of these pathological types of diverticulum are capable of harboring an enterolith. If the enterolith stays in place, it may cause no problems, but a large enterolith expelled from a diverticulum into the lumen can cause obstruction.

A diverticulum (plural: "diverticula") is the medical or biological term for an outpouching of a hollow (or a fluid-filled) structure in the body. Depending upon which layers of the structure are involved, they are described as being either true or false.

In medicine, the term usually implies the structure is not normally present. However, in the embryonic stage, some normal structures begin development as a diverticulum arising from another structure.

The following are risk factors that can result in a hiatus hernia.

- Increased pressure within the abdomen caused by:

- Heavy lifting or bending over

- Frequent or hard coughing

- Hard sneezing

- Violent vomiting

- Straining

- Stress

In simple words, when there is excessive pressure within the lower pharynx, the weakest portion of the pharyngeal wall balloons out, forming a diverticulum which may reach several centimetres in diameter.

More precisely, while traction and pulsion mechanisms have long been deemed the main factors promoting development of a Zenker's diverticulum, current consensus considers occlusive mechanisms to be most important: uncoordinated swallowing, impaired relaxation and spasm of the cricopharyngeus muscle lead to an increase in pressure within the distal pharynx, so that its wall herniates through the point of least resistance (known as Killian's triangle, located superior to the cricopharyngeus muscle and inferior to the Thyropharyngeus muscle. Thyropharyngeus and Laryngopharyngeus are the superior and inferior parts of inferior constrictor muscle of pharynx respectively). The result is an outpouching of the posterior pharyngeal wall, just above the esophagus.

While it may be asymptomatic, Zenker diverticulum can present with the following symptoms:

- Dysphagia (difficulty swallowing), and sense of a lump in the throat

- Food might get trapped in the outpouching, leading to:

- Regurgitation, reappearance of ingested food in the mouth

- Cough, due to food regurgitated into the airway

- Halitosis, smelly breath, as stagnant food is digested by microorganisms

- Infection

It rarely, if ever, causes any pain.

Cervical webs are seen associated in 50% of patients with this condition.

Rarer forms of cervical esophageal diverticula are the Killian's diverticulum and the Laimer's diverticulum. Killian's diverticulum is formed in the Killian-Jamiseon triangle (located inferior to the cricopharyngeus on both sides of this muscle's insertion into the cricoid cartilage). Laimer's diverticulum is formed in Laimer's triangle (located inferior to the cricopharyngeus in the posterior midline above the confluence of the longitudinal layer of esophageal muscle). Laimer's triangle is covered only by the circular layer of esophageal muscle.

A Killian–Jamieson diverticulum is an outpouching of the esophagus just below the upper esophageal sphincter.

The physicians that first discovered the diverticulum were Gustav Killian and James Jamieson. Diverticula are seldom larger than 1.5 cm, and are less frequent than the similar Zenker's diverticula. As opposed to a Zenker's, which is typically a posterior and inferior outpouching from the esophagus, a Killian–Jamieson diverticulum is typically an anterolateral outpouching at the level of the C5-C6 vertebral bodies, due to a congenital weakness in the cervical esophagus just below the cricopharyngeal muscle. It is usually smaller in size than a Zenker's diverticulum, and typically asymptomatic. Although congenital, it is more commonly seen in elderly patients.

Equine enteroliths are found by walking pastures or turning over manure compost piles to find small enteroliths, during necroscopy, and increasingly, during surgery for colic. Therefore, the incidence of asymptomatic enteroliths is unknown.

Equine enteroliths typically are smoothly spherical or tetrahedral, consist mostly of the mineral struvite (ammonium magnesium phosphate), and have concentric rings of mineral precipitated around a nidus.

Enteroliths in horses were reported widely in the 19th century, infrequently in the early 20th century, and now increasingly. They have also been reported in zebras: five in a zoo in California and one in a zoo in Wisconsin. Struvite enteroliths are associated with elevated pH and mineral concentrations in the lumen. In California, struvite enteroliths are associated also with a high proportion of alfalfa in the feed and less access to grass pasture. This association has been attributed to the cultivation of alfalfa on serpentine soils, resulting in high concentrations of magnesium in the alfalfa.

Most damage to the pyloric valve occurs as a complication of gastric surgery. Other causes of biliary reflux may be:

- Peptic ulcer

- Gallbladder surgery (cholecystectomy)

A significant fraction of cases are idiopathic, with no identified specific etiology.

Smoking has been linked to a variety of disorders of the stomach. Tobacco is known to stimulate acid production and impairs production of the protective mucus. This leads to development of ulcers in the majority of smokers.

Chronic stomach problems have also been linked to excess intake of alcohol. It has been shown that alcohol intake can cause stomach ulcer, gastritis and even stomach cancer. Thus, avoidance of smoking and excess alcohol consumption can help prevent the majority of chronic stomach disorders.

One of the most causes of chronic stomach problems is use of medications. Use of aspirin and other non-steroidal anti-inflammatory drugs to treat various pain disorders can damage lining of the stomach and cause ulcers. Other medications like narcotics can interfere with stomach emptying and cause bloating, nausea, or vomiting.

The majority of chronic stomach problems are treated medically. However, there is evidence that a change in life style may help. Even though there is no specific food responsible for causing chronic stomach problems, experts recommend eating a healthy diet which consists of fruits and vegetables. Lean meat should be limited. Moreover, people should keep a diary of foods that cause problems and avoid them.

Gastrointestinal perforation, also known as ruptured bowel, is a hole in the wall of part of the gastrointestinal tract. The gastrointestinal tract includes the esophagus, stomach, small intestine, and large intestine. Symptoms include severe abdominal pain and tenderness. When the hole is in the stomach or early part of the small intestine the onset of pain is typically sudden while with a hole in the large intestine onset may be more gradual. The pain is usually constant in nature. Sepsis, with an increased heart rate, increased breathing rate, fever, and confusion may occur.

The cause can include trauma such as from a knife wound, eating a sharp object, or a medical procedure such as colonoscopy, bowel obstruction such as from a volvulus, colon cancer, or diverticulitis, stomach ulcers, ischemic bowel, and a number of infections including "C. difficile". A hole allows intestinal contents to enter the abdominal cavity. The entry of bacteria results in a condition known as peritonitis or in the formation of an abscess. A hole in the stomach can also lead to a chemical peritonitis due to gastric acid. A CT scan is typically the preferred method of diagnosis; however, free air from a perforation can often be seen on plain X-ray.

Perforation anywhere along the gastrointestinal tract typically requires emergency surgery in the form of an exploratory laparotomy. This is usually carried out along with intravenous fluids and antibiotics. A number of different antibiotics may be used such as piperacillin/tazobactam or the combination of ciprofloxacin and metronidazole. Occasionally the hole can be sewn closed while other times a bowel resection is required. Even with maximum treatment the risk of death can be as high as 50%. A hole from a stomach ulcer occurs in about 1 per 10,000 people per year, while one from diverticulitis occurs in about 0.4 per 10,000 people per year.

Biliary reflux, bile reflux or duodenogastric reflux is a condition that occurs when bile flows upward (refluxes) from the duodenum into the stomach and esophagus.

Biliary reflux can be confused with acid reflux, also known as gastroesophageal reflux disease (GERD). While bile reflux involves fluid from the small intestine flowing into the stomach and esophagus, acid reflux is backflow of stomach acid into the esophagus. These conditions are often related, and differentiating between the two can be difficult.

Bile is a digestive fluid made by the liver, stored in the gallbladder, and discharged into duodenum after food is ingested to aid in the digestion of fat. Normally, the pyloric sphincter prevents bile from entering the stomach. When the pyloric sphincter is damaged or fails to work correctly, bile can enter the stomach and then be transported into the esophagus as in gastric reflux. The presence of small amounts of bile in the stomach is relatively common and usually asymptomatic, but excessive refluxed bile causes irritation and inflammation.

An enterolith is a mineral concretion or calculus formed anywhere in the gastrointestinal system. Enteroliths are uncommon and usually incidental findings but, once found, they require at a minimum watchful waiting. If there is evidence of complications, they must be removed.

An enterolith may form around a "nidus", a small foreign object such as a seed, pebble, or piece of twine, that serves as an irritant. In this respect, an enterolith forms by a process similar to the creation of a pearl.

An enterolith is not to be confused with a gastrolith, which helps digestion.

Underlying causes include gastric ulcers, duodenal ulcers, appendicitis, gastrointestinal cancer, diverticulitis, inflammatory bowel disease, superior mesenteric artery syndrome, trauma and ascariasis. Typhoid fever, non-steroidal anti-inflammatory drugs, ingestion of corrosives may also be responsible.

Cancers of the stomach are rare and the incidence has been declining worldwide. Stomach cancers usually occur due to fluctuations in acidity level and may present with vague symptoms of abdominal fullness, weight loss and pain. The actual cause of stomach cancer is not known but has been linked to infection with "Helicobacter pylori", pernicious anemia, Menetriere's disease, and nitrogenous preservatives in food.