Galbladder Disease in Dogs
Do dogs have a gallbladder?
Yes. Most vertebrates, which are creatures born with a spinal column, have gallbladders. Several species of mammals, including horses, deer and rats, as well as pigeons, some species of birds and all invertebrates (no spinal column), do not have gallbladders.
What does the gallbladder do?
The gallbladder is also known as the cholecyst. It is a small, hollow organ where bile is stored and concentrated before it is released into the small intestine through the bile duct. Bile is a substance secreted by the liver that assists with the digestion and absorption of fats and with the elimination of certain waste products from the body.
The pear-shaped gallbladder lies beneath the liver, although the size, structure and position of the gallbladder can vary significantly among different animal species. Gallbladder agenesis is a condition in which the gallbladder does not develop from birth. Unless the bile ducts within the liver are also missing, the lack of a gallbladder doesn’t cause any problems.
When food containing fat enters the digestive tract, it stimulates the secretion of cholecystokinin from cells in the small intestine. In response to cholecystokinin, the gallbladder rhythmically contracts and releases its contents into the common bile duct, eventually draining into the small intestine. The bile emulsifies fats in partly digested food, which helps them to be absorbed. Bile consists primarily of water and bile salts. It also acts as a means of eliminating bilirubin, which is a product of red-blood-cell metabolism, from the body.
The bile that is secreted by the liver and stored in the gallbladder is not the same as the bile that is secreted by the gallbladder. During the storage of bile in the gallbladder, it is concentrated 10-fold by removal of water and electrolytes.
How do I know if my dog has a problem with his gallbladder?
It is not fully known what causes gallbladder disease in dogs. Similar to humans, diets high in fat or cholesterol contribute to saturated bile. Clogged bile ducts and gallstones may develop over time. Liver disease may also secondarily cause gallbladder disease since the two organs work together in the body. An abdominal injury could lead to rupture of the gallbladder.
Jaundice, which is a yellow discoloration of the skin, gums and eyes, is the main sign of diseases of the gallbladder and bile duct. An exception to this is cancer of the gallbladder, which may not cause jaundice. Biliary atresia is a rare condition characterized by the lack of development of the bile ducts within the liver. Affected dogs are jaundiced and in poor condition at a young age. The prognosis for these puppies is grave.
Other symptoms of gallbladder issues are discomfort when urinating and passing blood in the urine. Weakness, loss of appetite, vomiting and abdominal pain may also occur.
What diseases are associated with the gallbladder and bile duct?
Obstruction of the bile duct occurs with a number of conditions, including inflammation of the pancreas, gallbladder or small intestines. Other causes are foreign material obstructing the intestines, cancer and severe parasite infestations. Tissue swelling, inflammation or fibrosis can result in compression and narrowing of the bile duct. The diagnosis of an obstructed bile duct is based on laboratory tests that show an elevated bilirubin level, along with X-rays and ultrasonography of the abdomen.
Abdominal exploratory surgery may be needed to diagnose and treat the obstruction. If a bout of pancreatitis is the reason the bile duct is blocked, the obstruction should resolve with treatment of the pancreatitis. If gallstones are the cause of the obstruction, surgery to remove the gallbladder may be necessary. If cancer is present, surgery can provide some relief but is not a cure.
Rupture of the gallbladder is most often due to gallstone obstruction, inflammation of the gallbladder, or blunt trauma. Rupture of the bile duct may also occur as the result of cancer or certain parasites. Rupture leads to leakage of bile into the abdomen, causing a serious condition called bile peritonitis. This condition may be fatal if the rupture is not repaired. The treatment is a surgical procedure to place a stent in the bile duct, remove the gallbladder, or connect the gallbladder with the small intestine.
Inflammation of the gallbladder, also called cholecystitis, can be caused by bacterial infections, cancer, trauma to the liver, gallbladder obstruction or blood clots. In some cases when the wall of the gallbladder is damaged, bile will leak into the abdomen and cause inflammation and a severe abdominal infection. This is also the potentially fatal bile peritonitis. Dogs with this condition may be in a state of shock due to the pain in their belly.
The inflammation can also spread to the surrounding branches of the bile duct and the liver. A diagnosis of cholecystitis is based on blood tests and abdominal ultrasound. It can be confirmed by biopsy for bacterial culture and tissue analysis. The treatment for cholecystitis usually consists of surgery to remove the gallbladder and appropriate antibiotic medication to treat the infection. With early intervention, the prognosis for recovery is good. The outlook is guarded in cases where treatment is delayed.
A gallbladder mucocele is an abnormal accumulation of bile within the bile ducts. This overload results in a bile-duct obstruction. As it expands, the mucocele can lead to inflammation, necrosis (tissue death) or rupture of the gallbladder.
This condition may be inherited in some breeds, including Shetland Sheepdogs. Underlying diseases, such as pancreatitis and liver disease, can also predispose dogs to the condition. Some mildly affected dogs will improve with medication alone. However, most will require surgery to remove the gallbladder. Liver biopsies are often taken during surgery. Antibiotic treatment is recommended for four to six weeks post-operatively.
Gallstones rarely cause disease. When they do occur, they are usually seen in middle-aged to older dogs. Small breeds are more commonly affected. The symptoms are the same as the other gallbladder conditions and include vomiting, jaundice and abdominal pain. In some cases, the dogs are asymptomatic and will show no signs of illness.
Gallstones are diagnosed by ultrasound. Since ultrasounds are used more frequently these days as a diagnostic tool, more cases of gallstones are being discovered. Medications, including antibiotics, can treat dogs with uncomplicated disease. Surgery to remove the stones may be necessary if they are obstructing the bile duct or causing cholecystitis. The gallbladder may also need to be removed.
An excess of bacteria and other deposits crystallize together to form gallstones. The stones can range in size from a poppy seed to a dime. An exact cause for their formation has not been determined, but diet seems to be the most significant contributing factor. Certain breeds are more prone to developing gallstones, including Miniature Schnauzers, Shetland Sheepdogs and Poodles.
What medication is prescribed for gallbladder issues?
Ursodiol is a bile-acid drug used to treat the symptoms of gallbladder or bile-related liver diseases such as gallbladder mucocele, cholestasis and chronic liver inflammation. The brand names for this medication are Actigall, Urso and Ursofalk. It is in a class of medications called gallstone dissolution agents.
Ursodiol works by decreasing the production of cholesterol and by dissolving the cholesterol in bile to prevent stone formation. It also decreases toxic levels of bile acids that accumulate in primary biliary cholangitis, which is a chronic disease in which the bile ducts in the liver are slowly destroyed.
Ursodiol is prescribed to dissolve gallstones when surgery is not a good option. It is also given to prevent the formation of gallstones in overweight people who are losing weight very quickly.
Its use in dogs to treat liver and gallbladder conditions is “off label.” This means it is not specifically approved for use in dogs. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully, as his or her instructions may be different from those on the label for human dosage.
Ursodiol comes in capsule, tablet or liquid suspension. It is administered by mouth and should be taken with food. The liquid forms should be measured carefully. Do not give ursodiol with antacids that contain aluminum, such as Mylanta, Gaviscon or Gelusil.
This medication must be taken for months to have an effect. Dissolving gallstones can take up to two years. It should be used cautiously in dogs that may have complications related to gallstones, such as bile-duct obstruction, cholecystitis or pancreatitis.