Canine gallbladder mucocele

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Canine gallbladder mucocele (GBM) is an emerging biliary disease in dogs described as the excessive and abnormal accumulation of thick, gelatinous mucus in the lumen, which results in an enlarged gallbladder. GBMs have been diagnosed more frequently in comparison to prior to the 2000s when it was considered rare. [1] The mucus is usually pale yellow to dark green in appearance.

Contents

The name originates from the Greek word kele meaning tumour as a mucocele resembles a mass. [2] Although this disease is primarily identified in dogs, cats and ferrets have also been diagnosed. [3]

Anatomy and function

The gallbladder is an excretory organ that is pear-shaped and identified between two liver lobes. It is divided into three sections a body, neck and fundus. [1] The main function of this excretory organ is storing, acidifying and concentrating bile. This is achieved due to the nature of the muscular sac being a thin wall that can easily distend to accommodate the bile. [2] It is collected from the liver cells via small channels that pass through the hepatic ducts and into the gallbladder. After a fatty meal the bile is then released into the small intestine promoted by a hormone called cholecystokinin that is present in the pancreas. [4]

This is important for canines in terms of digestive health as the bile can facilitate in breaking down large fat particles into smaller ones. And also enhances the intestinal absorption of nutrients including lipids, electrolytes and protein. [4]

Pathogenesis

The underlying pathogenesis and cause for a formation of a GBM is still yet to be identified. However, there is strong association with the rapid increase and hyperplasia of mucus-producing cells and hyper-secretion within the gallbladder epithelium. [5] This will lead to distension which refers to the enlargement of something due to internal pressures. [6] The pressure in this case is the thick mucus as it cannot be effectively expelled. [7] Without proper treatment the severity increases as the thickened material can cause obstruction in the bile ducts. This results in the risk of gallbladder rupture which is life-threatening thus early diagnosis is necessary. [8]

Additionally the composition of biliary sludge has been suggested to encourage the formation of a mucocele. Biliary sludge occurs when more water or mucin is reabsorbed and there is excessive bile salts. As this progresses more water is increased causing the contents to become more solid and severely decrease the motility of the gallbladder [7]

It is most likely that there are multiple factors that contribute to the formation of a gallbladder mucocele.

Predispositions

Most gallbladder mucoceles have been found in mid-age to older dogs with the median age being 9 with no sex predilection. [2] This is because he abnormal enlargement of mucus-producing glands in the gallbladder is often seen as a common feature amongst older dogs. Smaller dogs including Cocker Spaniels, Miniature Schnauzers, Pomeranians and Shetland Sheepdogs are also predisposed to developing gallbladder mucoceles as the mutation ABCB4 gene [3] has been associated and these breeds often show signs of lipid metabolism problems which can trigger the development. [9]

Some other conditions that can predispose a dog to a GBM includes:[ citation needed ]

Signs and symptoms

About 77% of dogs with a GBM display nonspecific and vague clinical signs that can last up to a week including; [10]

While other dogs with mucoceles show no clinical signs. [11]

Diagnosis

The diagnosis of gallbladder mucoceles is done by veterinarians and is dependent on an ultrasound examination. Additional procedures and diagnostics include physical examination and blood tests. Blood-work may reveal liver issues caused by obstruction of the common bile duct caused by sludge from the Gall Bladder. Serum Biochemical Profile (CHEM) of affected dogs with a GBM have shown elevated liver enzymes.

Thus a complete evaluation of all the major organ systems will be conducted during the diagnosis process. [8] 

Ultrasound imaging is generally the only effective and accurate diagnostic technique. They are often diagnosed 'accidentally' when diagnosing gastrointestinal illness due to the vague symptoms. [12]  With the presence of a gallbladder mucocele, the ultrasound will reveal a thickened wall and an enlarged 'kiwi-like' gallbladder filled with immobile, echogenic bile meaning it is not gravity dependent. Another clear indication in the images is striated or stellate patterns surrounding a small amount of stationary bile. The ultrasonographic can also indicate whether the gallbladder has ruptured. Signs of this include a discontinuous wall and presence of free abdominal fluid without indication of the gallbladder at all. [2]

Microbiologic sampling of the bile may also be conducted to identify potential bacterial infections including E.coli , Enterococcus , Staphylococcus , Enterobacter , Streptococcus , Micrococcus . [11] The bile is collected via a method called cholecystocentesis which is an ultrasound guided laparoscopy. However, there is potential complications that may occur during this procedure including the bacteria entering the bloodstream, haemorrhaging and bile leakage.[ citation needed ]

Treatment

Medical management is one option for select cases. Asymptomatic patients without the evidence of gallbladder rupture can be managed medically with a drug treatment plan formulated by a veterinarian however their GBM will not be resolved in this case. [5] Antibiotics are prescribed for a period of 6 to 8 weeks to the patient depending on the bacteria that is isolated in the bacterial cultures and microbiologic sampling. The bile could also reveal more than one infection present, in this case a combination of medications is often given. [11] To promote the excretion of excessive bile chloritic drugs can also be prescribed to manage the GBM.[ citation needed ] This is used to increase the bile flow by deliberately minimising the cholesterol content in the bile as well as diluting the secretions to allow it to exit more freely via the bile ducts. This occurs due to a naturally occurring bile acid present in the drug called Ursodiol. Hepatoprotectants are simultaneously prescribed to protect the liver as the gallbladder lives between two liver lobes, it works to protect it from bile acids. [11] Dogs who are being medically managed must be rechecked for mucoceles after 4 to 6 weeks of being on antibiotics. If there are no signs of improvement and the symptoms are worsening surgery is necessary.[ citation needed ]

Surgical removal of the gallbladder also known as cholecystectomy is recommended at initial detection to avoid spontaneous gallbladder rupture since the rate of leakage or rupture is unpredictable this also removes the potential for a reoccurring GBM. [13] If the patient shows clinical signs, abnormal blood work and pain the removal of the gall bladder is necessary. In case of rupture they should undergo immediate emergency surgery. [14]

Before surgery begins preoperative tests must be conducted to look at a patient's blood count, urine analysis, serum chemistry profile and coagulation panel. This is to ensure that all results and levels are normal and do not display anything that isn't expected. This is necessary to commence surgery. However this would have been completed during the diagnosing process unless immediate surgery is necessary. All patients are also given appropriate intravenous fluids and electrolytes. These steps are necessary to reduce the risks of anaesthesia because most patients are older aged dogs. [11]

During surgical procedures the whole abdominal cavity is checked in case of any concurrent and or occult problems. The bile ducts will be commonly be expressed to perform biopsies of the liver as well as the collection of bile and liver samples for further diagnosis. If the patients gallbladder has ruptured the cavity will be extensively flushed and the abdominal drained. [2]

In some cases which are more severe, particularly when the canines gallbladder has already ruptured, feeding tubes may be placed preemptively if the veterinarian is concerned about their ability to eat post surgery. If the common bile duct is plugged, the surgeon may have to open the duodenum opposite of where the common bile duct enters the small intestine and flush it with a catheter. [13]

Some complications that may occur due to this procedure includes vomiting, bile peritonitis if bile leaks into the abdominal cavity, pancreatitis and in some cases death. [11] The mortality rate for this ranges between 22 and 32%, with approx. a two-week mortality. Patients that successfully undergo and complete surgery show excellent long-term survival. [8]

After care

After surgery, intravenous fluids will be continued to ensure the canine's hydration as well as pain-reliefs to ensure complete recovery. They will also remain hospitalised for up to 48 hours so that veterinarians can monitor their behaviour and response to surgery especially their appetite. [15]

Once released back home the incision from surgery should be frequently checked to avoid infection, the use of an Elizabethan collar may be necessary to prevent them from licking the wound. For 14 days their exercise regime must be restricted and they must avoid running, jumping, stairs and extensive off leash activity. [10] Antibiotics will be prescribed to any infections found from the culture taken during surgery. A low fat diet is also often recommended by veterinarians to reduce further complications in the future. [8]

Related Research Articles

<span class="mw-page-title-main">Gallbladder</span> Organ in humans and other vertebrates

In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, although the structure and position of the gallbladder can vary significantly among animal species. It receives bile, produced by the liver, via the common hepatic duct, and stores it. The bile is then released via the common bile duct into the duodenum, where the bile helps in the digestion of fats.

<span class="mw-page-title-main">Gallstone</span> Disease where stones form in the gallbladder

A gallstone is a stone formed within the gallbladder from precipitated bile components. The term cholelithiasis may refer to the presence of gallstones or to any disease caused by gallstones, and choledocholithiasis refers to the presence of migrated gallstones within bile ducts.

<span class="mw-page-title-main">Cholecystitis</span> Inflammation of the gallbladder

Cholecystitis is inflammation of the gallbladder. Symptoms include right upper abdominal pain, pain in the right shoulder, nausea, vomiting, and occasionally fever. Often gallbladder attacks precede acute cholecystitis. The pain lasts longer in cholecystitis than in a typical gallbladder attack. Without appropriate treatment, recurrent episodes of cholecystitis are common. Complications of acute cholecystitis include gallstone pancreatitis, common bile duct stones, or inflammation of the common bile duct.

<span class="mw-page-title-main">Cholecystectomy</span> Surgical removal of the gallbladder

Cholecystectomy is the surgical removal of the gallbladder. Cholecystectomy is a common treatment of symptomatic gallstones and other gallbladder conditions. In 2011, cholecystectomy was the eighth most common operating room procedure performed in hospitals in the United States. Cholecystectomy can be performed either laparoscopically, or via an open surgical technique.

Courvoisier's principle states that a painless palpably enlarged gallbladder accompanied with mild jaundice is unlikely to be caused by gallstones. Usually, the term is used to describe the physical examination finding of the right-upper quadrant of the abdomen. This sign implicates possible malignancy of the gallbladder or pancreas and the swelling is unlikely due to gallstones.

<span class="mw-page-title-main">Gastrointestinal disease</span> Illnesses of the digestive system

Gastrointestinal diseases refer to diseases involving the gastrointestinal tract, namely the esophagus, stomach, small intestine, large intestine and rectum; and the accessory organs of digestion, the liver, gallbladder, and pancreas.

<span class="mw-page-title-main">Common bile duct stone</span> Medical condition

Common bile duct stone, also known as choledocholithiasis, is the presence of gallstones in the common bile duct (CBD). This condition can cause jaundice and liver cell damage. Treatments include choledocholithotomy and endoscopic retrograde cholangiopancreatography (ERCP).

<span class="mw-page-title-main">Gallbladder cancer</span> Medical condition

Gallbladder cancer is a relatively uncommon cancer, with an incidence of fewer than 2 cases per 100,000 people per year in the United States. It is particularly common in central and South America, central and eastern Europe, Japan and northern India; it is also common in certain ethnic groups e.g. Native American Indians and Hispanics. If it is diagnosed early enough, it can be cured by removing the gallbladder, part of the liver and associated lymph nodes. Most often it is found after symptoms such as abdominal pain, jaundice and vomiting occur, and it has spread to other organs such as the liver.

Adenomyoma is a tumor (-oma) including components derived from glands (adeno-) and muscle (-my-). It is a type of complex and mixed tumor, and several variants have been described in the medical literature. Uterine adenomyoma, the localized form of uterine adenomyosis, is a tumor composed of endometrial gland tissue and smooth muscle in the myometrium. Adenomyomas containing endometrial glands are also found outside of the uterus, most commonly on the uterine adnexa but can also develop at distant sites outside of the pelvis. Gallbladder adenomyoma, the localized form of adenomyomatosis, is a polypoid tumor in the gallbladder composed of hyperplastic mucosal epithelium and muscularis propria.

<span class="mw-page-title-main">Ascending cholangitis</span> Medical condition

Ascending cholangitis, also known as acute cholangitis or simply cholangitis, is inflammation of the bile duct, usually caused by bacteria ascending from its junction with the duodenum. It tends to occur if the bile duct is already partially obstructed by gallstones.

Neonatal cholestasis refers to elevated levels of conjugated bilirubin identified in newborn infants within the first few months of life. Conjugated hyperbilirubinemia is clinically defined as >20% of total serum bilirubin or conjugated bilirubin concentration greater than 1.0 mg/dL regardless of total serum bilirubin concentration. The differential diagnosis for neonatal cholestasis can vary extensively. However, the underlying disease pathology is caused by improper transport and/or defects in excretion of bile from hepatocytes leading to an accumulation of conjugated bilirubin in the body. Generally, symptoms associated with neonatal cholestasis can vary based on the underlying cause of the disease. However, most infants affected will present with jaundice, scleral icterus, failure to thrive, acholic or pale stools, and dark urine.

<span class="mw-page-title-main">Biliary colic</span> Medical condition in which gallstones cause acute pain

Biliary colic, also known as symptomatic cholelithiasis, a gallbladder attack or gallstone attack, is when a colic occurs due to a gallstone temporarily blocking the cystic duct. Typically, the pain is in the right upper part of the abdomen, and can be severe. Pain usually lasts from 15 minutes to a few hours. Often, it occurs after eating a heavy meal, or during the night. Repeated attacks are common. Cholecystokinin - a gastrointestinal hormone - plays a role in the colic, as following the consumption of fatty meals, the hormone triggers the gallbladder to contract, which may expel stones into the duct and temporarily block it until being successfully passed.

<span class="mw-page-title-main">Gallbladder disease</span> Medical condition

Gallbladder diseases are diseases involving the gallbladder and is closely linked to biliary disease, with the most common cause being gallstones (cholelithiasis).

<span class="mw-page-title-main">Abdominal ultrasonography</span> Type of medical scan

Abdominal ultrasonography is a form of medical ultrasonography to visualise abdominal anatomical structures. It uses transmission and reflection of ultrasound waves to visualise internal organs through the abdominal wall. For this reason, the procedure is also called a transabdominal ultrasound, in contrast to endoscopic ultrasound, the latter combining ultrasound with endoscopy through visualize internal structures from within hollow organs.

<span class="mw-page-title-main">Cholescintigraphy</span> Medical imaging of hepatobiliary tract using radiotracers

Cholescintigraphy or hepatobiliary scintigraphy is scintigraphy of the hepatobiliary tract, including the gallbladder and bile ducts. The image produced by this type of medical imaging, called a cholescintigram, is also known by other names depending on which radiotracer is used, such as HIDA scan, PIPIDA scan, DISIDA scan, or BrIDA scan. Cholescintigraphic scanning is a nuclear medicine procedure to evaluate the health and function of the gallbladder and biliary system. A radioactive tracer is injected through any accessible vein and then allowed to circulate to the liver, where it is excreted into the bile ducts and stored by the gallbladder until released into the duodenum.

Biliary dyskinesia is a disorder of some component of biliary part of the digestive system in which bile cannot physically move in the proper direction through the tubular biliary tract. It most commonly involves abnormal biliary tract peristalsis muscular coordination within the gallbladder in response to dietary stimulation of that organ to squirt the liquid bile through the common bile duct into the duodenum. Ineffective peristaltic contraction of that structure produces postprandial right upper abdominal pain (cholecystodynia) and almost no other problem. When the dyskinesia is localized at the biliary outlet into the duodenum just as increased tonus of that outlet sphincter of Oddi, the backed-up bile can cause pancreatic injury with abdominal pain more toward the upper left side. In general, biliary dyskinesia is the disturbance in the coordination of peristaltic contraction of the biliary ducts, and/or reduction in the speed of emptying of the biliary tree into the duodenum.

Secondary sclerosing cholangitis (SSC) is a chronic cholestatic liver disease. SSC is a sclerosing cholangitis with a known cause. Alternatively, if no cause can be identified, then primary sclerosing cholangitis is diagnosed. SSC is an aggressive and rare disease with complex and multiple causes. It is characterized by inflammation, fibrosis, destruction of the biliary tree and biliary cirrhosis. It can be treated with minor interventions such as continued antibiotic use and monitoring, or in more serious cases, laparoscopic surgery intervention, and possibly a liver transplant.

Oral cholecystography is a radiological procedure used to visualize the gallbladder and biliary channels, developed in 1924 by American surgeons Evarts Ambrose Graham and Warren Henry Cole. It is usually indicated in cases of suspected gallbladder disease, and can also be used to determine or rule out the presence of intermittent obstruction of the bile ducts or recurrent biliary disease after biliary surgery.

<span class="mw-page-title-main">Sphincter of Oddi dysfunction</span> Medical condition

Sphincter of Oddi dysfunction refers to a group of functional disorders leading to abdominal pain due to dysfunction of the Sphincter of Oddi: functional biliary sphincter of Oddi and functional pancreatic sphincter of Oddi disorder. The sphincter of Oddi is a sphincter muscle, a circular band of muscle at the bottom of the biliary tree which controls the flow of pancreatic juices and bile into the second part of the duodenum. The pathogenesis of this condition is recognized to encompass stenosis or dyskinesia of the sphincter of Oddi ; consequently the terms biliary dyskinesia, papillary stenosis, and postcholecystectomy syndrome have all been used to describe this condition. Both stenosis and dyskinesia can obstruct flow through the sphincter of Oddi and can therefore cause retention of bile in the biliary tree and pancreatic juice in the pancreatic duct.

<span class="mw-page-title-main">Biloma</span> Circumscribed abdominal collection of bile outside the biliary tree

A biloma is a circumscribed abdominal collection of bile outside the biliary tree. It occurs when there is excess bile in the abdominal cavity. It can occur during or after a bile leak. There is an increased chance of a person developing biloma after having a gallbladder removal surgery, known as laparoscopic cholecystectomy. This procedure can be complicated by biloma with incidence of 0.3–2%. Other causes are liver biopsy, abdominal trauma, and, rarely, spontaneous perforation. The formation of biloma does not occur frequently. Biliary fistulas are also caused by injury to the bile duct and can result in the formation of bile leaks. Biliary fistulas are abnormal communications between organs and the biliary tract. Once diagnosed, they usually require drainage. The term "biloma" was first coined in 1979 by Gould and Patel. They discovered it in a case with extrahepatic bile leakage. The cause of this was trauma to the upper right quadrant of the abdomen. Originally, biloma was described as an "encapsulated collection" of extrahepatic bile. Biloma is now described as extrabiliary collections of bile that can be either intrahepatic or extrahepatic. The most common cause of biloma is trauma to the liver. There are other causes such as abdominal surgery, endoscopic surgery and percutaneous catheter drainage. Injury and abdominal trauma can cause damage to the biliary tree. The biliary tree is a system of vessels that direct secreations from the liver, gallbladder, and pancreas through a series of ducts into the duodenum. This can result in a bile leak which is a common cause of the formation of biloma. It is possible for biloma to be associated with mortality, though it is not common. Bile leaks occur in about one percent of causes.

References

  1. 1 2 DACVIM, Audrey K. Cook BVM&S MRCVS DACVIM DECVIM-CA Rebecca Quinn DVM. "An update on gallbladder mucoceles in dogs". dvm360.com. Retrieved 2018-11-03.
  2. 1 2 3 4 5 Cornejo L, Webster CR (December 2005). "Canine Gallbladder Mucoceles" (PDF). Compendium on Continuing Education for the Practising Veterinarian. 27 (12) (North American ed.): 912–930.
  3. 1 2 "Canine Gallbladder Mucocele (GBM)". AnimaLabs. Retrieved 2018-10-19.
  4. 1 2 3 "Gallbladder Mucoceles in Dogs". CriticalCareDVM. 2014-09-15. Retrieved 2018-10-19.
  5. 1 2 "Canine Gallbladder Mucocele - Digestive System". Veterinary Manual. Retrieved 2018-10-05.
  6. ↑ "Definition of Distention". MedicineNet. Retrieved 2018-11-04.
  7. 1 2 Norwich A (March 2011). "Gallbladder mucocele in a 12-year-old cocker spaniel". The Canadian Veterinary Journal. 52 (3): 319–21. PMC   3039909 . PMID   21629430.
  8. 1 2 3 4 "Gallbladder Mucocele in Dogs". Animal Surgical Center of Michigan. Retrieved 2018-09-30.
  9. 1 2 "Gallbladder Obstruction in Dogs". petMD. Retrieved 2018-09-30.
  10. 1 2 "Gallbladder Mucocele". ACVS. Retrieved 2018-09-30.
  11. 1 2 3 4 5 6 Cook AK, Quinn R (April 2009). "An update on gallbladder mucoceles in dogs". dvm360.com. Retrieved 2018-10-05.
  12. ↑ Gookin JL, Correa MT, Peters A, Malueg A, Mathews KG, Cullen J, Seiler G (2015). "Association of Gallbladder Mucocele Histologic Diagnosis with Selected Drug Use in Dogs: A Matched Case-Control Study". Journal of Veterinary Internal Medicine. 29 (6): 1464–72. doi:10.1111/jvim.13649. PMC   4895658 . PMID   26478445.
  13. 1 2 Yaphe W (June 2013). "gallbladder mucocele". Veterinary Voice. Longmont, CO: Aspen Meadow Vet. Retrieved 2018-10-19.
  14. ↑ "New Thoughts on Gallbladder Mucoceles". Veterinary Practice News. 2014-06-02. Retrieved 2018-10-05.
  15. ↑ "Gallbladder Mucocele Q&A". atdove.org. 2013-03-15. Retrieved 2018-10-05.
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