An update on gallbladder mucoceles in dogs
Other hepatoprotectants. Silymarin (milk thistle) should also be instituted (Table 2). This nutraceutical alters the composition of hepatocyte membranes and limits the entry of hepatotoxins into cells.31 It also stimulates protein synthesis and hepatic regeneration.31 Silymarin contains flavonoids such as silybin, silydianin, and silychristin, which increase glutathione concentrations and provide antioxidant effects.31 Inhibition of the inflammatory effects of leukotrienes is also reported.31
S-adenosylmethionine (SAMe) is a precursor to glutathione and has antioxidant effects (Table 2).32 It also enhances DNA repair.32 While studies clearly indicate that milk thistle and SAMe protect hepatocytes from damage, studies have not confirmed that either is useful in dogs with mucoceles.31,32
Monitoring. Reexamine dogs undergoing medical therapy for mucoceles after four to six weeks. The recheck should include abdominal ultrasonography, a complete blood count, and a serum chemistry profile. In one report involving two dogs, alanine aminotransferase and alkaline phosphatase activities and total bilirubin concentrations remained elevated for weeks to months after ultrasonographic resolution of the mucocele.1 These persistent elevations are most likely associated with the extension of pathological processes from the gallbladder to the liver or from a concurrent hepatic or endocrine (e.g. hyperadrenocorticism, hypothyroidism, diabetes mellitus) condition.Prognosis. The prognosis for patients treated medically appears to be variable. In one study, seven of 25 patients with mucoceles were treated with ursodiol and SAMe. Two died within two weeks, two were lost to follow-up, and three survived without complications for at least six months.12
In a recent case study, two clinically ill patients with mucoceles were successfully managed with medical therapy.1 One dog was treated with SAMe, omega-3 fatty acids, famotidine, ursodiol, and levothyroxine. The second dog received ursodiol, fenbendazole, and levothyroxine and was fed a hypoallergenic diet. Levothyroxine was used to treat hypothyroidism, and fenbendazole was used for prophylactic gastrointestinal parasite therapy. These patients showed complete ultrasonographic resolution of the mucocele after two and three months.1
Surgical intervention should be recommended in all dogs that fail to improve with medical therapy, including those with unresolved clinical signs, worsening laboratory findings, and progressing ultrasonographic abnormalities.
Gallbladder mucoceles are being diagnosed with increasing frequency in dogs, but their true incidence remains uncertain. The underlying cause of this condition is still controversial, but there is a strong association with mucous gland hyperplasia within the gallbladder epithelium. While surgical management has been the historic treatment of choice, recent case-based evidence suggests that some patients may respond to medical management.
Rebecca Quinn, DVM
1. Walter R, Dunn ME, d'Anjou MA, et al. Nonsurgical resolution of gallbladder mucocele in two dogs. J Am Vet Med Assoc 2008;232(11):1688-1693.
2. Samuelson DA. Textbook of veterinary histology. 1st ed. Philadelphia, Pa: WB Saunders Co, 2006;367-369.
3. Guyton AC, Hall JE. Textbook of medical physiology. 11th ed. Philadelphia, Pa: Elsevier Inc, 2006;802-804.
4. Ko CW, Sekijima JH, Lee SP. Biliary sludge. Ann Intern Med 1999;130(4):301-311.
5. Brömel C, Barthez PY, Léveillé R, et al. Prevalence of gallbladder sludge in dogs as assessed by ultrasonography. Vet Radiol Ultrasound 1998;39(3):206-210.
6. Tsurumi K, Onda M. A fluorescence histochemical study for the motility of the gallbladder. Gastroenterol Jpn 1979;14(2):147-154.
7. Guo YS, Singh P, Gomez G, et al. Contractile response of canine gallbladder and sphincter of Oddi to substance P and related peptides in vitro. Dig Dis Sci 1989;34(6):812-817.
8. Milenov K, Vassileva M, Marinova D, et al. Effect of neurotensin on the canine gallbladder motility: in vivo and in vitro experiments. Neuropeptides 1993;25(4):233-239.
9. Strah KM, Melendez RL, Pappas TN, et al. Interactions of vasoactive intestinal polypeptide and cholecystokinin octapeptide on the control of gallbladder contraction. Surgery 1986;99(4):469-473.
10. Harkema JR, Mason MJ, Kusewitt DF, et al. Cholecystotomy as treatment for obstructive jaundice in a dog. J Am Vet Med Assoc 1982;181(8):815-816.
11. Neer TM. A review of disorders of the gallbladder and extrahepatic biliary tract in the dog and cat. J Vet Intern Med 1992;6(3):186-192.
12. Aguirre AL, Center SA, Randolph JF, et al. Gallbladder disease in Shetland sheepdogs: 38 cases (1995-2005). J Am Vet Med Assoc 2007;231(1):79-88.
13. Bernhoft RA, Pellegrini CA, Broderick WC, et al. Pigment sludge and stone formation in the acutely ligated dog gallbladder. Gastroenterology 1983;85(5):1166-1171.
14. Newell SM, Selcer BA, Mahaffey MB, et al. Gallbladder mucocele causing biliary obstruction in two dogs: ultrasonographic, scintigraphic, and pathological findings. J Am Anim Hosp Assoc 1995;31(6):467-472.
15. Selman PJ, van Garderen E, Mol JA, et al. Comparison of the histological changes in the dog after treatment with the progestins medroxyprogesterone acetate and proligestone. Vet Q 1995;17(4):128-133.
16. Lee SP, Nicholls JF. Nature and composition of biliary sludge. Gastroenterology 1986;90(3):677-686.
17. Besso JG, Wrigley RH, Gliatto JM, et al. Ultrasonographic appearance and clinical findings in 14 dogs with gallbladder mucocele. Vet Radiol Ultrasound 2000;41(3):261-271.
18. Pike FS, Berg J, King NW, et al. Gallbladder mucocele in dogs: 30 cases (2000-2002). J Am Vet Med Assoc 2004;224(10):1615-1622.
19. Klinkspoor JH, Yoshida T, Lee SP. Bile salts stimulate mucin secretion by cultured dog gallbladder epithelial cells independent of their detergent effect. Biochem J 1998;332(Pt 1):257-262.
20. Worley DR, Hottinger HA, Lawrence HJ. Surgical management of gallbladder mucoceles in dogs: 22 cases (1999-2003). J Am Vet Med Assoc 2004;225(9):1418-1422.
21. Cornejo L, Webster CRL. Canine gallbladder mucoceles. Compend Contin Educ Pract Vet 2005;27(12)912-930.
22. North DC. Sudden death in a dog associated with cholelithiasis. Vet Rec 1977;101(11):203.
23. Finn ST, Park RD, Twedt DC, et al. Ultrasonographic assessment of sincalide-induced canine gallbladder emptying: an aid to the diagnosis of biliary obstruction. Vet Radiol 1991;32(6):269-276.
24. Wagner KA, Hartmann FA, Trepanier LA. Bacterial culture results from liver, gallbladder, or bile in 248 dogs and cats evaluated for hepatobiliary disease: 1998-2003. J Vet Intern Med 2007;21(3):417-424.
25. Amsellem PM, Seim HB 3rd, MacPhail CM, et al. Long-term survival and risk factors associated with biliary surgery in dogs: 34 cases (1994-2004). J Am Vet Med Assoc 2006;229(9):1451-1457.
26. Mehler SJ, Mayhew PD, Drobatz KJ, et al. Variables associated with outcome in dogs undergoing extrahepatic biliary surgery: 60 cases (1988-2002). Vet Surg 2004;33(6):644-649.
27. Vörös K, Sterczer A, Manczur F, et al. Percutaneous ultrasound-guided cholecystocentesis in dogs. Acta Vet Hung 2002;50(4):385-393.
28. Herman BA, Brawer RS, Murtaugh RJ, et al. Therapeutic percutaneous ultrasound-guided cholecystocentesis in three dogs with extrahepatic biliary obstruction and pancreatitis. J Am Vet Med Assoc 2005;227(11):1782-1786.
29. Rivers BJ, Walter PA, Johnston GR, et al. Acalculous cholecystitis in four canine cases: ultrasonographic findings and use of ultrasonographic-guided, percutaneous cholecystocentesis in diagnosis. J Am Anim Hosp Assoc 1997;33(3):207-214.
30. Crosignani A, Setchell KDR, Invernizzi P, et al. Clinical pharmacokinetics of therapeutic bile acids. Clin Pharmacokinet 1996;30(5):333-358.
31. Flora K, Hahn M, Rosen H, et al. Milk thistle (Silybum marianum) for the therapy of liver disease. Am J Gastroenterol 1998;93(2):139-143.
32. Muriel P, Rivera-Espinoza Y. Beneficial drugs for liver diseases. J Appl Toxicol 2008;28(2):93-103.