Extrahepatic biliary tract surgery has been associated with high morbidity and mortality rates in humans and dogs, despite advances in surgical technique and supportive care.1 Such surgery includes cholecystectomy, cholecystotomy, choledochotomy, choledochal stent placement, and cholecystoenterostomy (cholecystoduodenostomy or cholecystojejunostomy).2 Reported mortality rates for dogs undergoing various types of extrahepatic biliary tract surgery range from 7% to 50%.1,3–10 The mortality rate for cholecystectomy alone in dogs ranges from 7% to 33.3% and in humans is approximately 30%, with a better prognosis possible when performed in response to GBM versus other biliary diseases.2,3,5,6,11
Indications for extrahepatic biliary tract surgery include GBM, pancreatitis leading to biliary tract obstruction, obstructive cholelithiasis, inflammatory biliary tract disease, and neoplasia.3,4 The most common indication is GBM.5,12 The incidence of GBM has been increasing since the 1990s, and GBM is now one of the most common causes of extrahepatic biliary tract disease in dogs.3 Whether this represents a true increase in the incidence of GBM or improvements in early clinical detection remains unclear.5 Dog breeds reportedly predisposed to GBM development include Shetland Sheepdog, Cocker Spaniel, and Miniature Schnauzer, with Shetland Sheepdogs 7.2 times as likely to develop GBM as other breeds.13
The etiopathogenesis of GBM development is unknown and is likely multifactorial.3,13 One hypothesis is that hyperplasia of the mucus-secreting glands leads to increased mucus accumulation within the lumen of the gallbladder.3,14 Whether cystic hyperplasia of the gallbladder wall represents an inherited disease process or biliary dyskinesia leads to increased exposure of the epithelium to bile salts and therefore increased epithelial turnover is still unknown.13 Mucocele formation can lead to distention and pressure necrosis of the wall with subsequent rupture and bile peritonitis.
The clinical signs associated with GBM are often nonspecific and include lethargy, anorexia, vomiting, and diarrhea.3,5,6 However, some dogs have no or minimal clinical signs, and mucoceles are a reported incidental finding at necropsy.14 In 2 studies,13,15 44% of dogs with GBMs identified during abdominal ultrasonographic examination for another disease process or during investigation of high liver enzyme activity had no signs of GBM.
Early interventional cholecystectomy for nonobstructive cholelithiasis in human medicine has been shown to significantly lower morbidity and mortality rates.16 Similar results might be expected for dogs that undergo early interventional cholecystectomy.2 To the authors' knowledge, no study has been conducted to determine the mortality rate of elective cholecystectomy in dogs. The purpose of the study reported here was to compare the mortality rate for elective cholecystectomy with that for nonelective cholecystectomy and identify any variables that may affect survival to hospital discharge. We hypothesized that the mortality rate for elective cholecystectomy would be significantly lower than that for nonelective cholecystectomy in dogs with biliary tract disease.
Materials and Methods
Animals
Medical records of a companion animal referral practice from February 2009 to July 2015 were searched to identify those with a mention of GBM, serum ALP activity greater than serum ALT activity, hyperbilirubinemia (serum total bilirubin concentration ≥ 0.3 mg/dL), icterus, and cholecystectomy. Dogs with one or a combination of these characteristics that underwent cholecystectomy for GBM or other biliary tract diseases were included. Dogs that underwent biliary diversion surgery and cats were excluded.
Data collection
Information was collected from the medical records regarding dog signalment (ie, age, sex, reproductive status, and breed), clinical signs at initial evaluation, and results of CBC and serum biochemical analysis. Findings of preoperative ultrasonography, if performed, were recorded and the presence of any extrahepatic biliary tract obstruction, gallbladder rupture, and focal peritonitis was noted. Histologic examination and bile culture results were recorded when available. Important intraoperative findings, including presence or absence of gallbladder rupture, signs of extrahepatic biliary tract obstruction, and hypotension, were recorded as well as any surgical procedures performed concurrently with the cholecystectomy. Gallbladder rupture was deemed present if a rupture of the gallbladder was seen during surgery or bile was seen leaking from the biliary tree. Perioperative hypotension was defined as a systolic arterial blood pressure < 100 mm Hg or mean arterial blood pressure < 60 mm Hg.
Dogs were then grouped by whether the performed cholecystectomy had been elective or nonelective. Cholecystectomy was considered elective when dogs had no clinical signs or had a combination of nonspecific clinical signs (eg, vomiting, anorexia or inappetence, and lethargy) and when ultrasonography had revealed a maturing mucocele or distended gallbladder with no obstruction. This group also included dogs deemed stable with no requirement for surgery on an emergent basis and those that underwent abdominal exploration for another reason (eg, obstructive urolithiasis, liver mass, or splenic mass) and had cholecystectomy performed concurrently. Cholecystectomy was considered nonelective when dogs had icterus or questionable patency of the biliary system (ie, biliary tract obstruction).
Statistical analysis
Statistical analyses were performed with the aid of statistical software.a Values of continuous variables (ie, age, clinicopathologic test results, blood pressure, and duration of hospitalization) were compared between dogs in the elective and nonelective groups and were evaluated for associations with outcome (survival or nonsurvival to hospital discharge) by means of the Student t test. These data are reported as mean ± SD. The Satterthwaite procedure was used in the event of unequal variances between groups.
Associations between outcome and the overall presence of clinical signs as well as the presence of individual clinical signs, gallbladder rupture identified during surgery, and each specific type of surgical procedure performed during cholecystectomy (but not abdominal ultrasonographic or histologic findings) were evaluated by use of the exact Pearson χ2 test. For all tests, values of P < 0.05 were considered significant.
Results
Animals
Seventy dogs (31 [44%] males and 39 [56%] females) with a mean ± SD age of 10.2 ± 2.4 years (range, 4 to 16 years) were included in the study. Of the male dogs, 27 (87%) were castrated and 4 (13%) were sexually intact. Thirty-eight (97%) female dogs were spayed, and 1 (3%) was sexually intact. The sexually intact female was spayed during the cholecystectomy procedure. Dogs were classified as Shetland Sheepdog (n = 8), mixed-breed dog (8), Miniature Schnauzer (7), Chihuahua (5), Pomeranian (4), Scottish Terrier (3), Shih Tzu (3), Cocker Spaniel (3), Beagle (3), Pug (2), Jack Russell Terrier (2), Labrador Retriever (2), and various other breeds (1 each).
Forty-five (64%) dogs were classified as having undergone elective cholecystectomy, and 25 (36%) dogs were classified as having undergone nonelective cholecystectomy. Overall, 6 of the 70 (9%) dogs failed to survive to hospital discharge.
Clinical signs
Forty-eight (69%) dogs had at least 1 clinical sign of biliary tract disease at initial evaluation, and 22 (31%) dogs had no clinical signs. The predominant clinical signs were anorexia or inappetence (n = 30 [43%]), vomiting (29 [41%]), lethargy (23 [33%]), and icterus (16 [23%]). Additional clinical signs or conditions included weight loss (7 [10%]), pyrexia (6 [9%]), diarrhea (5 [7%]), abdominal distention or signs of abdominal pain (4 [6%]), hematemesis (3 [4%]), melena (2 [3%]), coughing (2 [3%]), and urinary tract obstruction (1 [1%]). No significant (P = 0.17) association was identified between overall presence or absence of clinical signs and outcome (survival or nonsurvival to hospital discharge). In analyses involving individual clinical signs, only vomiting (P = 0.004), anorexia (P = 0.004), lethargy (P = 0.013), and icterus (P = 0.002) were significantly associated with outcome, in that dogs with these signs were more likely to have failed to survive to discharge than dogs without these signs.
Clinicopathologic test results
Fifty-two (74%) dogs had a complete serum biochemical analysis performed prior to surgery, whereas the remaining 18 (26%) dogs had results of a partial or preoperative serum biochemical analysis available. Fifty-seven (81%) dogs had complete CBC performed, and only 44 (63%) dogs had both a complete serum biochemical analysis and CBC performed. Several serum biochemical abnormalities were identified, including high ALT (57/70 [81%]), ALP (65/69 [94%]), GGT (38/62 [61%]), lipase (11/60 [18%]), and amylase (8/65 [12%]) activities; high total bilirubin (34/65 [52%]), triglycerides (15/55 [27%]), cholesterol (35/61 [57%]), BUN (12/68 [18%]), and creatinine (5/66 [8%]) concentrations; and low albumin (10/66 [15%]) and total calcium (8/65 [12%]) concentrations. A high WBC count was identified in 17 of 57 (30%) dogs, and a low Hct was identified in 7 of 55 (13%) dogs.
Serum ALT activity and total bilirubin and albumin concentrations were the only serum biochemical analytes significantly associated with outcome (Table 1) in that dogs that failed to survive to hospital discharge had greater ALT activity and total bilirubin concentration and lower albumin concentration than dogs that survived. Azotemia (BUN concentration > 31 mg/dL with or without a serum creatinine concentration > 1.6 mg/dL) was also significantly (P = 0.02) associated with failure to survive. Dogs in the nonelective cholecystectomy group had significantly greater serum ALT, ALP, and GGT activities; serum total bilirubin concentration; and WBC count and lower serum albumin concentration than dogs in the elective cholecystectomy group (Table 2). No other clinicopathologic values differed significantly between those groups.
Mean ± SD values of serum biochemical and CBC analytes for dogs that survived or failed to survive to hospital discharge following cholecystectomy to treat biliary tract disease.
| Â | Â | Survivors | Â | Nonsurvivors | ||
|---|---|---|---|---|---|---|
| Analyte | Reference interval | No. of dogs | Value | No. of dogs | Value | P value |
| ALT (U/L) | 12–118 | 64 | 714.4 ± 931.2 | 6 | 1,645.0 ± 1,214.8 | 0.03 |
| ALP (U/L) | 5–131 | 63 | 2,360.6 ± 2,618.7 | 6 | 3,859.5 ± 2,943.4 | 0.19 |
| GGT (U/L) | 1–12 | 56 | 47.8 ± 58.0 | 6 | 31.8 ± 20.6 | 0.19 |
| Total bilirubin (mg/dL) | 0.1–0.3 | 59 | 2.42 ± 3.97 | 6 | 7.57 ± 4.80 | 0.004 |
| Albumin (g/dL) | 2.7–4.4 | 60 | 3.34 ± 0.60 | 6 | 2.73 ± 0.45 | 0.02 |
| Calcium (mg/dL) | 8.9–11.4 | 59 | 10.1 ± 0.97 | 6 | 9.73 ± 0.82 | 0.38 |
| Amylase (U/L) | 290–1,125 | 60 | 709.2 ± 363.9 | 5 | 798.8 ± 392.6 | 0.61 |
| Lipase (U/L) | 77–665 | 55 | 525.0 ± 803.0 | 5 | 664.6 ± 766.1 | 0.71 |
| Cholesterol (mg/dL) | 92–324 | 55 | 415.9 ± 241.5 | 6 | 371.8 ± 101.1 | 0.42 |
| Triglycerides (mg/dL) | 29–291 | 52 | 282.7 ± 429.2 | 3 | 2,428.7 ± 1,091.5 | 0.08 |
| BUN (mg/dL) | 6–31 | 63 | 18.9 ± 18.6 | 5 | 45.5 ± 48.0 | 0.23 |
| Creatinine (mg/dL) | 0.5–1.6 | 60 | 0.88 ± 0.59 | 6 | 2.03 ± 1.73 | 0.17 |
| WBCs (× 103 cells/μL) | 4.0–15.5 | 52 | 12.3 ± 6.1 | 5 | 28.2 ± 19.1 | 0.14 |
| Hct (%) | 36–60 | 51 | 45.1 ± 7.4 | 4 | 46.6 ± 2.6 | 0.69 |
Values of P < 0.05 were considered significant. Numbers of dogs represent those with available data.
Mean ± SD values of serum biochemical and CBC analytes for the dogs in Table 1, categorized by whether the cholecystectomy had been elective or nonelective.
| Â | Elective | Nonelective | Â | ||
|---|---|---|---|---|---|
| Analyte | No. of dogs | Value | No. of dogs | Value | P value |
| ALT (U/L) | 45 | 581.4 ± 852.2 | 25 | 1,177.2 ± 1,101.1 | 0.01 |
| ALP (U/L) | 45 | 1,597.4 ± 980.9 | 24 | 4,211.7 ± 2,950.9 | < 0.001 |
| GGT (U/L) | 40 | 33.3 ± 48.8 | 22 | 68.0 ± 60.1 | 0.02 |
| Total bilirubin (mg/dL) | 40 | 0.77 ± 1.55 | 25 | 6.38 ± 5.01 | < 0.001 |
| Albumin (g/dL) | 41 | 3.49 ± 0.52 | 25 | 2.95 ± 0.60 | < 0.001 |
| Amylase (U/L) | 41 | 692.5 ± 288.8 | 24 | 755.7 ± 467.3 | 0.55 |
| Lipase (U/L) | 39 | 612.6 ± 932.6 | 21 | 395.6 ± 422.3 | 0.22 |
| Cholesterol (mg/dL) | 38 | 413.9 ± 257.7 | 23 | 407.5 ± 180.9 | 0.92 |
| Triglycerides (mg/dL) | 38 | 356.3 ± 547.4 | 17 | 505.5 ± 925.2 | 0.54 |
| BUN (mg/dL) | 43 | 22.81 ± 21.29 | 25 | 18.60 ± 26.68 | 0.48 |
| Creatinine (mg/dL) | 43 | 0.99 ± 0.66 | 23 | 0.98 ± 1.05 | 0.95 |
| WBCs (× 103 cells/μL) | 36 | 11.16 ± 6.06 | 21 | 18.05 ± 11.38 | 0.02 |
| Hct (%) | 35 | 45.78 ± 6.90 | 20 | 44.12 ± 7.76 | 0.42 |
See Table 1 for key.
Abdominal ultrasonographic findings
All dogs received an abdominal ultrasonographic examination; however, examination findings were available for review for only 69 dogs. Two dogs had no mention of the gallbladder and its appearance in the examination report; therefore, only 67 reports were available for evaluation. Thirty-six of the 67 (54%) dogs with information recorded regarding the gallbladder had ultrasonographic evidence of a GBM with a stellate or so-called kiwi-fruit pattern. The remaining 31 (46%) dogs had mineralization within the gallbladder or a combination of a distended gallbladder with hyperechoic and organized bile sediment. Local peritonitis, evidenced by hyperechoic cranial mesenteric fat or fluid surrounding the gallbladder, was suspected in 19 (28%) dogs, distended bile ducts were suspected in 6 (9%) dogs, gallbladder rupture was suspected in 4 (6%) dogs, and extrahepatic biliary tract obstruction was suspected in 2 (3%) dogs.
Surgical findings
Sixty-seven (96%) dogs had a surgery report available for review. Procedures performed in addition to cholecystectomy included liver biopsy (n = 67 [100%]), cystotomy (16 [24%]), feeding tube placement (12 [18%], splenectomy (9 [13%]), gastrointestinal surgery including gastrotomy and enterotomy (8 [12%]), liver lobectomy (3 [4%]), abdominal drain placement (3 [4%]), adrenal gland biopsy (2 [3%]), skin biopsy or mass removal (2 [3%]), ovariohysterectomy (1 [1%]), gastropexy (1 [1%]), lymph node biopsy (1 [1%]), renal biopsy (1 [1%]), and debridement of a pancreatic abscess (1 [1%]). One (1%) dog received blood products during surgery.
No specific additional surgical procedure performed in conjunction with cholecystectomy was associated with outcome. For 18 (27%) dogs, aspiration of the duodenum was performed to confirm patency of the bile duct. Catheterization of the bile duct was performed in a normograde fashion for 6 (9%) dogs and in a retrograde fashion for 4 (6%) dogs. Thirtynine (58%) dogs had neither aspiration nor catheterization performed.
Free abdominal fluid (ie, ascites, bile, serosanguinous, or hemorrhagic fluid) was recorded for 10 (15%) dogs, signs of focal peritonitis (ie, adhesions of the gallbladder to the omentum, falciform fat, or stomach) were recorded for 21 (31%) dogs, and gallbladder rupture was recorded for 4 (6%) dogs. Gallbladder rupture had been confirmed directly (n = 3) or via leakage of bile from the biliary tree (1) during surgery and was not significantly (P = 0.08) associated with outcome.
Sixty-two of 70 (89%) dogs had results of intraoperative blood pressure monitoring available for review, of which 46 (74%) had hypotension during surgery. Among hypotensive dogs, the mean ± SD value for systolic arterial blood pressure was 35.4 ± 11.6 mm Hg (range, 40 to 91 mm Hg) and for mean arterial blood pressure was 21.3 ± 8.0 mm Hg (range, 34 to 71 mm Hg). Mean ± SD duration of hospitalization was 3.3 ± 1.5 days (range, 1 to 8 days). Neither intraoperative hypotension (P = 0.59) nor duration of hospitalization (P = 0.051) was significantly associated with outcome.
Histologic findings
The gallbladders of 63 (90%) dogs were histologically examined. Findings included GBM alone (n = 27 [43%]) or with cystic mucinous hyperplasia (5 [8%]), cholecystitis (3 [5%]), or choleliths (3 [5%]); cystic mucinous hyperplasia alone (19 [30%]) or with cholecystitis (4 [6%]) or choleliths (1 [2%]); cholecystitis alone (13 [21%]) or with choleliths (1 [2%]) or gallbladder rupture (1 [2%]); necrosis and hemorrhage with invasion of carcinoid neoplastic cells from the liver into the gallbladder (1 [2%]); mild hyperplasia of mucosa with focal necrosis and perforation (1 [2%]); chronic fibrosis with multifocal lymphocytic and histiocytic infiltration and granulation tissue (1 [2%]); and moderate hyperplasia with dilatation (1 [2%]). Only 2 dogs had histologically confirmed gallbladder rupture, with concurrent multifocal necrosis in one dog and concurrent cholecystitis in the other.
Bacterial culture of bile samples
Bile samples were obtained from 60 (86%) dogs during surgery for aerobic bacterial culture and antimicrobial susceptibility testing. Antimicrobials had not been withheld prior to bile sample collection. Samples from 13 (22%) dogs yielded growths of pathogenic and nonpathogenic bacteria. The pathogenic bacteria included Enterococcus spp (n = 5), Staphylococcus spp (4; 2 Staphylococcus pseudintermedius, 1 methicillin-resistant S pseudintermedius, and 1 unspecified species), Escherichia coli (3), and Pseudomonas aeruginosa (1). A sample from 1 of the 13 dogs that yielded growth of methicillin-resistant S pseudintermedius also yielded growths of 2 additional nonpathogenic bacteria (Alcaligenes faecalis subsp faecalis and Bacillus sp). Another sample from 1 of the 13 dogs yielded growth of only a nonpathogenic bacterium (a diphtheroid). Eight dogs with a positive culture result had undergone elective cholecystectomy, whereas 5 dogs had undergone nonelective cholecystectomy. A positive culture result was not significantly (P = 0.39) associated with outcome.
Elective versus nonelective cholecystectomy
One dog in the elective group died of cardiopulmonary arrest. Two dogs that failed to survive in the nonelective group had been euthanized during surgery because of a poor prognosis, and the other 3 dogs died of cardiopulmonary arrest after surgery. Dogs in the nonelective group had a significantly (P = 0.02) higher mortality rate (5/25 [20%]) than dogs in the elective group (1/45 [2%]).
Discussion
Cholecystectomy, a common surgical procedure in companion animal medicine, has historically been associated with a mortality rate as high as 33%.11 The overall mortality rate associated with this procedure in the present study (9%) was less than most previously reported rates for dogs and cats,1,3,4,6–11 with a few exceptions (7% within the immediate 2-week postoperative period and 16.7% within 2 months after surgery5). The mortality rate for nonelective cholecystectomy in the present study (20%) was significantly greater than that for elective cholecystectomy (2%).
A high proportion of dogs that underwent cholecystectomy for GBM in the present study were Shetland Sheepdogs or Miniature Schnauzers, consistent with previous findings.13 Clinical signs at initial evaluation were often nonspecific, and the most common were vomiting and signs of lethargy and anorexia, consistent with previously reported findings for dogs and cats with biliary tract disease.5,8 Icterus, a more specific indicator of hepatobiliary disease, was also common solely within the nonelective group. Although dogs with vomiting, anorexia, lethargy, or icterus had a significantly higher mortality rate than dogs without these signs, vomiting, anorexia, and lethargy could be considered nonspecific and might have been attributable instead or in part to concurrent diseases not controlled for in the analysis. Icterus is an indicator of advanced biliary tract disease and therefore may explain its association with a higher mortality rate. No other clinical signs were significantly associated with outcome, nor was the overall presence of clinical signs.
Reported negative prognostic factors in the preoperative period for humans undergoing cholecystectomy include malignancy, age > 60 years, pyrexia, leukocytosis, azotemia, hypoalbuminemia, hyperbilirubinemia, anemia, and high serum ALP activity.17 Similar preoperative risk factors have been reported for dogs as well as prolonged partial thromboplastin time; high band neutrophil count; high serum creatinine, BUN, and phosphorus concentrations; and high serum GGT activity.1,7 Clinicopathologic findings for dogs in the present study were similar to those in previous reports.1,7 Nonsurvivors had greater serum ALT activity, greater serum total bilirubin concentration, and lower serum albumin concentration than did survivors. No other clinicopathologic values differed significantly between these groups. Prior research15 has indicated that dogs with clinical signs of GBM have a greater WBC count, serum ALT and ALP activities, and serum total bilirubin concentration than do dogs without those signs, which is also consistent with the present findings. Dogs that underwent elective (vs nonelective) cholecystectomy in the present study had higher serum concentrations of albumin; lower serum activities of ALT, ALP, and GGT; and a lower serum total bilirubin concentration. No other clinicopathologic values differed significantly between the elective and nonelective groups.
The most sensitive method for diagnosis of GBM is abdominal ultrasonography.6 Distinctive ultrasonographic GBM patterns have been reported, including immobile sludge that does not change with gravity or echogenic bile in a stellate (most common) or finely striated kiwi-fruit pattern.15 In the present study, GBM was diagnosed in 36 dogs via abdominal ultrasonography. Eighteen dogs had a stellate pattern, and 1 dog had a kiwi-fruit pattern.
Surgical findings for dogs in the present study did not always coincide with ultrasonographic findings. Twenty-one dogs had surgical evidence of focal peritonitis, but only 12 of these dogs also had signs of peritonitis on ultrasonographic examination. Similarly, 4 dogs had suspected gallbladder rupture as determined via abdominal ultrasonography, but in only 2 of these dogs was rupture confirmed at the time of surgery. Ten dogs also had confirmed free abdominal fluid during surgery, and this corresponded with the ultrasonographic findings in 6 dogs. However, gallbladder rupture was not significantly associated with mortality rate, nor was performance of surgical procedures in addition to the cholecystectomy.
Controversy exists in the veterinary literature regarding whether to catheterize the common bile duct or aspirate the duodenum to establish the patency of the bile duct.3,5,18 In the present study, catheterization of the bile duct was performed in 10 dogs, and aspiration of bile from the duodenum was attempted to establish patency of the extrahepatic biliary tree in 18 dogs. For 38 dogs, no such procedures were performed, predominantly because the surgeon could see bile flowing through the common bile duct and into the duodenum during surgery. Regardless of the technique, no dogs required additional surgery for biliary obstruction during the hospitalization period.
Positive results of bacterial culture of bile samples had no association with outcome in the present study. Evidence indicates that the presence of bacteria in biliary effusions is associated with a mortality rate > 20% in humans, suggesting that low bacterial load can improve the survival rate.19 The prophylactic use of antimicrobials after laparoscopic and conventional cholecystectomy is associated with a lower perioperative morbidity rate and briefer hospitalization period in human medicine.20 Peri- and postoperative administration of antimicrobials is recommended for dogs undergoing cholecystectomy, particularly if gallbladder rupture is suspected.3,13
The present retrospective study had several limitations, including a lack of randomization, lack of controls regarding treatment options and techniques, and lack of evaluation of longer-term postoperative complications. In addition, incomplete medical records may have contributed to low statistical power for some comparisons.
Regardless of these limitations, our findings indicated that the prognosis for dogs undergoing elective cholecystectomy for GBM was good, as suggested by the low mortality rate. The reason for cholecystectomy for some dogs was biliary disease other than GBM, so this mortality rate did not apply solely to dogs with GBM. This information may be useful when counseling clients about cholecystectomy, particularly elective cholecystectomy, given that mortality rates in the present study were lower than previously reported. Surgical treatment of GBM should be recommended after an ultrasonographic diagnosis is made, even if the patient lacks severe clinical signs at the time, given that nonelective surgery had a significantly higher mortality rate in this and other studies2,12,21 involving dogs and cats.
Acknowledgments
Presented in abstract form at the 15th Annual Society of Veterinary Soft Tissue Surgery, Jackson Hole, Wyo, June 2016.
ABBREVIATIONS
| ALP | Alkaline phosphatase |
| ALT | Alanine aminotransferase |
| GBM | Gallbladder mucocele |
| GGT | γ-Glutamyltransferase |
Footnotes
SAS, version 9.3, SAS Institute, Cary, NC.
References
1. 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;33:644–649.
2. Mehler SJ. Complications of the extrahepatic biliary surgery in companion animals. Vet Clin North Am Small Anim Pract 2011;41:949–967.
3. Pike FS, Berg J, King NW, et al. Gallbladder mucocele in dogs: 30 cases (2000–2002). J Am Vet Med Assoc 2004;224:1615–1622.
4. Amsellem PM, Seim HB III, 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;229:1451–1457.
5. Malek S, Sinclair E, Hosgood G, et al. Clinical findings and prognostic factors for dogs undergoing cholecystectomy for gallbladder mucocele. Vet Surg 2013;42:418–426.
6. Worley DR, Hottinger HA, Lawrence HJ. Surgical management of gallbladder mucoceles in dogs: 22 cases (1999–2003). J Am Vet Med Assoc 2004;225:1418–1422.
7. Papazoglou LG, Mann FA, Wagner-Mann C, et al. Long-term survival of dogs after cholecystoenterostomy: a retrospective study of 15 cases (1981–2005). J Am Anim Hosp Assoc 2008;44:67–74.
8. Morrison S, Prostredny J, Roa D. Retrospective study of 28 cases of cholecystoduodenostomy performed using endoscopic gastrointestinal anastomosis stapling equipment. J Am Anim Hosp Assoc 2008;44:10–18.
9. Crews LJ, Feeney DA, Jessen CR, et al. Clinical, ultrasonographic, and laboratory findings associated with gallbladder disease and rupture in dogs: 45 cases (1997–2007). J Am Vet Med Assoc 2009;234:359–366.
10. Ludwig LL, McLoughlin MA, Graves TK, et al. Surgical treatment of bile peritonitis in 24 dogs and 2 cats: a retrospective study (1987–1994). Vet Surg 1997;26:90–98.
11. Besso JG, Wrigley RH, Gliatto JM, et al. Ultrasonographic appearance and clinical findings in 14 dogs with gallbladder mucocele. Vet Radiol Ultrasound 2000;41:261–271.
12. Burns BR, Hofmeister EH, Brainard BM. Anesthetic complications in dogs undergoing hepatic surgery: cholecystectomy versus non-cholecystectomy. Vet Anaesth Analg 2014;41:186–190.
13. Aguirre AL, Center SA, Randolph JF, et al. Gallbladder disease in Shetland Sheepdogs: 38 cases (1995–2005). J Am Vet Med Assoc 2007;231:79–88.
14. Mayhew PD, Mehler SJ, Radhakrishnan A. Laparoscopic cholecystectomy for management of uncomplicated gallbladder mucocele in six dogs. Vet Surg 2008;37:625–630.
15. Choi J, Kim A, Keh A, et al. Comparison between ultrasonographic and clinical findings in 43 dogs with gallbladder mucoceles. Vet Radiol Ultrasound 2014;55:202–207.
16. Pitt HA, Murray KP, Bowman HM, et al. Clinical pathway implementation improves outcomes for complex biliary surgery. Surgery 1999;124:751–756.
17. Pitt HA, Cameron JL, Postier RG, et al. Factors affecting mortality in biliary tract surgery. Am J Surg 1981;14:66–72.
18. Mayhew PD, Richardson RW, Mehler SJ, et al. Choledochal tube stenting for decompression of the extrahepatic portion of the biliary tract in dogs: 13 cases (2002–2005). J Am Vet Med Assoc 2006;228:1209–1214.
19. Ackerman NB, Sillin LF, Suresh MD. Consequences of intraperitoneal bile: bile ascites versus bile peritonitis. Am J Surg 1985;149:244–246.
20. Lippert H, Gastinger J. Antimicrobial prophylaxis in laparoscopic and conventional cholecystectomy. Conclusions of a large prospective multicenter quality assurance study in Germany. Chemotherapy 1998;44:355–363.
21. Bunch SE. Hepatobiliary disease in the dog. In: Nelson RW, Guillermo Couto C, eds. Small animal internal medicine. 3rd ed. St Louis: Mosby Elsevier, 2003;538–540.
