Bloat Jan 12, 2009 18:50:42 GMT -5
Post by charmingnancy on Jan 12, 2009 18:50:42 GMT -5
What is Bloat?
Bloat is a medical condition in which the stomach becomes overstretched by excessive gas content. It is also commonly referred to as torsion, gastric torsion, and gastric dilatation-volvulus (GDV) when the stomach is also twisted. The word bloat is often used as a general term to cover gas distension of the stomach with or without twisting.
What causes bloat?
Bloat in dogs is likely caused by a multitude of factors, but in all cases the immediate prerequisite is a dysfunction of the sphincter between the esophagus and stomach and an obstruction of outflow through the pylorus (region of the stomach that connects to the small intestine). Some of the more widely acknowledged factors for developing bloat include increased age, breed, having a deep and narrow chest, stress, eating foods such as kibble that expand in the stomach, overfeeding, and other causes of gastrointestinal disease and distress.
Which breeds are most affected by bloat?
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 bloat has been estimated to be close to 37 percent. Standard Poodles are also at risk for this health problem, as are Doberman Pinschers and Rottweilers. Basset Hounds have the greatest risk for dogs less than 23 kg/50 lbs.
What are the symptoms?
Symptoms are not necessarily distinguishable from other kinds of distress. A dog might stand uncomfortably and seem to be in extreme discomfort for no apparent reason. Other possible symptoms include firm distension of the abdomen, weakness, depression, difficulty breathing, hypersalivation, and retching without vomiting. A high rate of dogs with bloat have cardiac arrhythmias (40 percent in one study). Chronic bloat may occur in dogs, symptoms of which include loss of appetite, vomiting and weight loss.
How does it happen?
The stomach twists around the longitudinal axis of the digestive tract, also known as volvulus. Gas distension may occur prior to or after the stomach twists. The most common direction for rotation is clockwise, viewing the animal from behind. The stomach can rotate up to 360° in this direction and 90° counterclockwise. If the volvulus is greater than 180°, the esophagus is closed off, thereby preventing the animal from relieving the condition by belching or vomiting. The results of this distortion of normal anatomy and gas distension include hypotension (low blood pressure), decreased return of blood to the heart, ischemia (loss of blood supply) of the stomach, and shock. Pressure on the portal vein decreases blood flow to liver and decreases the ability of that organ to remove toxins and absorbed bacteria from the blood. At the other end of the stomach, the spleen may be damaged if the twisting interrupts its blood supply. If not quickly treated, bloat can lead to blood poisoning, peritonitis and death by toxic shock. Bloat is an emergency medical condition: having the animal examined by a veterinarian is imperative. Bloat can become fatal within a matter of minutes.
What is the treatment?
A dog owner can sometimes relieve the immediate pressure of bloat by passing a tube down the throat, as an emergency first aid technique. This is not an easy task and cannot readily be improvised. Treatment usually involves resuscitation with intravenous fluid therapy, usually a combination of isotonic fluids and hypertonic saline or a colloidal solution such as hetastarch, and emergency surgery. The stomach is initially decompressed by passing a stomach tube, or if that is not possible, multiple trocars can be passed through the skin into the stomach to remove the gas. During surgery, the stomach is placed back into its correct position, the abdomen is examined for any devitalized tissue (especially the stomach and spleen). A partial gastrectomy (partial removal of the stomach) may be necessary if there is any necrosis of the stomach wall.
What can be done to prevent recurrence?
Recurrence of bloat attacks can be a problem, occurring in up to 80 percent of dogs treated medically only (without surgery). To prevent recurrence, at the same time the bloat is treated surgically, a right-side gastropexy is often performed, which by a variety of methods firmly attaches the stomach wall to the body wall, to prevent it from twisting inside the abdominal cavity in future. While dogs that have had gastropexies still may develop gas distension of the stomach, there is a significant reduction in recurrence of gastric volvulus. One study showed that out of 136 dogs that had surgery for bloat, 4.3 percent of those that did have gastropexies had a recurrence, while 54.5 percent of those without the additional surgery recurred.
How can it be prevented?
Precautions that are likely to help prevent bloat include feeding small meals throughout the day instead of one big meal and not exercising immediately before or after a meal.