Functional and morphological relationships between the feline main pancreatic and bile duct sphincters

Histologic characterization of the major duodenal papilla and association with concurrent biliary, pancreatic, and intestinal pathology in cats

Conjoining of the major pancreatic duct and common bile duct at the major duodenal papilla (MDP) is suspected to predispose cats to the clinical syndrome of "triaditis." However, microanatomy of the MDP or presence of lesions at the MDP has not been assessed in cats with or without triaditis. The aims of this study were to characterize feline MDP histomorphology and to identify associations between MDP anatomy/disease and the presence of biliary, pancreatic, or intestinal inflammation or neoplasia. Histologic assessment was prospectively performed on the MDP, duodenum, jejunum, ileum, liver, and pancreas from 124 client-owned cats undergoing postmortem examination. The majority of cats (104/124, 84%) had a complex ductular network at the MDP, with no distinction between pancreatic and common bile ducts. Lymphoid aggregates at the MDP were common (63/124, 51%). Inflammation of the MDP (MDPitis) was present in 35 of 124 cats (28%) and was often concurrent with cholangitis, pancreatitis, or enteritis (32/35, 91%), but was only associated with enteritis (19/35, 54%, P < .05). Triaditis was less common (19/124, 15%), but was associated with both conjoined MDP anatomy (19/19, 100%, P < .05) and MDPitis (12/19, 63%, P < .05). Neoplasia was present in 37 of 124 cats (29%), with lymphoma (28/37, 78%) predominating. Enteropathy-associated T-cell lymphoma type 2 (EATL2) was most common (n = 16/37, 43%) and was associated with triaditis and MDPitis (P < .05). These findings suggest that anatomy, immune activation, and/or inflammation of the MDP may play a role in the pathogenesis of triaditis. Further studies are needed to elucidate the relationships between triaditis, MDPitis, and EATL2.

Surgical Management Of Feline Biliary Tract Disease: Decision-making and techniques

PRACTICAL RELEVANCE

Diseases of the hepatobiliary system are not uncommon in first-opinion practice. The anatomy of the feline hepatobiliary tract differs from that of dogs and may predispose cats to inflammatory hepatobiliary disease. Case management can be challenging, and the prognosis is variable and dependent on the underlying disease process.

CLINICAL CHALLENGES

Biliary tract disease in the cat has non-specific clinical signs that overlap with those of diseases of other body systems. Diagnostic tests of the hepatobiliary system are widely available, but interpretation of results can be challenging. Deciding on medical or surgical management can also be challenging; for example, various degrees of cholestasis may be seen with different diseases and disease severities, and will influence the decision to manage the patient medically or surgically. Surgery is indicated in cases of bile peritonitis, severe cholestasis, focal neoplasia or disease that is refractory to medical management. Intensive perioperative and postoperative management, with 24 h hospitalisation facilities, is essential.

AUDIENCE

This review article is written for the small animal general/primary care practitioner, with an emphasis on decision-making in the surgical management of feline hepatobiliary disease.

EVIDENCE BASE

Evidence available in the published literature is reviewed and presented, and the inherent limitations are discussed.

Pancreatic Abscess in a Cat with Diabetes Mellitus

An 11 yr old spayed female Maine coon cat was referred with uncontrolled diabetes mellitus. The cat had a 2 mo history of weight loss and intermittent vomiting. An abdominal ultrasound identified the presence of a large cavity measuring a maximum of 4.6 cm in the pancreas that was filled with a homogeneous echogenic fluid. Cytological analysis and culture of the fluid obtained from the pancreatic mass indicated the presence of a bacterial abscess. The application of nonsurgical drainage and the administration of glargine insulin and antibiotics resolved the clinical signs. The size of the pancreatic abscess was reduced after 5 mo, and the cat achieved diabetic remission and remained healthy at the time this report was prepared. This case report describes the successful treatment of a pancreatic bacterial abscess concurrent with diabetes mellitus in a Maine coon cat.

A series of six cases of sphincter of Oddi pathology in the cat (2008–2009)

The sphincter of Oddi (SO) is located within the wall of the duodenum as the terminal part of the common bile duct. Six cats are reported with obstructive processes within their SO. Three of them may have had some form of sphincter dysfunction associated with the pre-existing complex known as ‘inflammatory bowel disease’ (IBD), two may have had the equivalent of the infant human condition known as ‘bile plug syndrome’ and the sixth had sphincter dysfunction associated with a tumour at the confluence of the common and right hepatic duct. In all six cases, the sphincter obstructions were surgically managed. The outcomes for 4/6 were favourable but 1/6 was euthanased intraoperatively, and 1/6 had a metastatic neoplasia and was euthanased 2 months postoperatively.

Transdermal glyceryl trinitrate for prevention of post-ERCP pancreatitis: A randomized double-blind trial

BACKGROUND

Pancreatic sphincter hypertension increases the risk of pancreatitis in patients undergoing ERCP. Glyceryl trinitrate reduces sphincter of Oddi pressure. This study tested the hypothesis that transdermal glyceryl trinitrate could be effective in the prevention of post-ERCP pancreatitis.

METHODS

One hundred forty-four patients undergoing ERCP were randomized: 71 received a 15-mg glyceryl trinitrate patch (glyceryl trinitrate group) and 73 a placebo patch (control group).

RESULTS

In the control group, post-ERCP pancreatitis developed in 11 patients versus 3 in the glyceryl trinitrate group (p < 0.05). Twenty-four hour to baseline serum amylase and lipase ratios were lower in the glyceryl trinitrate group (respectively, 3.6 vs. 7.5, p < 0.05; and 5.3 vs. 27.7, p < 0.05). In a multivariate analysis, glyceryl trinitrate patch and the number of pancreatic injections, but not endoscopic sphincterotomy, were independent risk factors for post-ERCP pancreatitis.

CONCLUSIONS

The results of this study suggest that use of a transdermal glyceryl trinitrate patch protects against post-ERCP pancreatitis.

Pathogenesis and outcome of extrahepatic biliary obstruction in cats

Extrahepatic biliary obstruction (EHBO) was confirmed at surgery or necropsy in 22 cats. Biliary or pancreatic adenocarcinoma was diagnosed by histopathology in six cats and one cat had an undiagnosed mass in the common bile duct. The remaining 15 cats had at least one of a complex of inflammatory diseases including pancreatitis, cholangiohepatitis, cholelithiasis and cholecystitis. The most common clinical signs were jaundice, anorexia, lethargy, weight loss and vomiting. Hyperbilirubinaemia was present in all cases. Distension of the common bile duct and gall bladder was the most commonly observed finding on abdominal ultrasound. Nineteen cats underwent exploratory laparotomy for biliary decompression and diversion. Mortality in cats with underlying neoplasia was 100 per cent and, in those with non-neoplastic lesions, was 40 per cent. Long-term complications, in those that survived, included recurrence of cholangiohepatitis, chronic weight loss and recurrence of obstruction. Based on these findings, the prognosis for EHBO in cats must be considered guarded.

Secretin induces variable inhibition of motility in different parts of the Australian possum sphincter of Oddi

The sphincter of Oddi (SO) may not function as a single structure. We aimed to determine the response of the proximal and distal segments of the bile duct (BD-SO) and pancreatic duct (PD-SO) components of the SO to secretin, with and without neural blockade with tetrodotoxin (TTX). In anaesthetized Australian possums, separate manometry catheters were placed in the proximal and distal BD-SO or PD-SO segments to record motility. Secretin, 50-1000 ng kg(-1), was administered, followed by TTX, and re-administration of secretin, 500 and 1000 ng kg(-1). Changes in the motility index (MI, frequency x mean amplitude) were determined. Statistical analysis utilized repeated-measures ANOVA. Secretin produced a dose-dependent decrease in MI from the proximal and distal BD-SO and PD-SO (all P < 0.001). The maximum inhibition, at 1000 ng kg(-1), was 21 +/- 4%, 33 +/- 6% and 42 +/- 5% of control (mean +/- SEM), for proximal and distal BD-SO, and distal PD-SO, respectively. The proximal PD-SO MI, however, was inhibited to 62 +/- 6% of control, at 1000 ng kg(-1). TTX enhanced the secretin-induced response to the same level at the four sites (P < 0.02). We conclude that secretin inhibits the motility of the possum SO in a nonuniform manner and is modulated by neural activity.

Local somatothermal stimulation inhibits the motility of sphincter of Oddi in cats, rabbits and humans through nitrergic neural release of nitric oxide

To examine whether and how local somatothermal stimulation inhibits the function of the sphincter of Oddi (SO) in humans and in animals with different types of SO, we measured the activity of SO in anesthetized cats and rabbits by using continuously perfused open-tip manometric methods. Local somatothermal stimulation was achieved by applying an electroheating rod 0.5 cm away from the skin area near the right subcostal region. A heating pad was applied to the corresponding area in patients undergoing endoscopic retrograde cholangiopancreatography and biliary manometry. The motility of the biliary tract in cats, in terms of gall bladder pressure, tonic and phasic contraction pressure and frequency of SO before and during local heat were significantly different, respectively. The local heat-induced SO relaxation was not inhibited by pretreatment with atropine, propranolol, phentolamine or anti-cholecystokinin-octapeptide, but was almost completely blocked by infiltration of local anesthetics. Pretreatment with a nitric oxide synthesis inhibitor also blocked the relaxation, which was reversed by pretreatment with L-arginine, but not by D-arginine. The inhibition of SO motility by local heat in rabbits was also blocked by pretreatment with L-NAME, and this blockade was reversed by L-arginine. Application of local heat on patients demonstrated obvious inhibitory SO responses. We conclude that local somatothermal stimulation inhibits the SO motility in animals with different types of SO through the activation of heat-sensitive neural release of nitric oxide. This procedure may represent a simplified approach for the treatment of diseases with hypofunction of the L-arginine/NO pathway.

Alcohol and the pancreas

Alcoholic pancreatitis is a major, often lethal complication of alcohol abuse. Until recently it was generally accepted that alcoholic pancreatitis was a chronic disease from the outset. However, there is now emerging evidence in favour of the necrosis-fibrosis hypothesis that alcoholic pancreatitis begins as an acute process and that repeated acute attacks lead to chronic pancreatitis, resulting in exocrine and endocrine failure. Over the past 10-15 years, the focus of research into the pathogenesis of alcoholic pancreatitis has shifted from possible sphincteric and ductular abnormalities to the acinar cell itself which has increasingly been implicated as the initial site of injury. Recent studies have shown that the acinar cell can metabolize alcohol at rates comparable to those observed in hepatocytes. In addition, it has been demonstrated that alcohol and its metabolites exert direct effects on the pancreatic acinar cell which may promote premature digestive enzyme activation and oxidant stress. The challenge remains to identify predisposing and triggering factors in this disease.

Raised pressure in the bile ducts after orthotopic liver transplantation

Biliary complications are common after orthotopic liver transplantation. Bile leakage in the immediate postoperative period and on removal of the T-tube could possibly be caused by a raised bile duct pressure. In order to test this hypothesis, bile duct pressure was studied in seven consecutive liver transplant patients. During the operation, the common bile duct was anastomosed end-to-end over a T-tube. The initial bile duct pressure measurement was performed a median of 12 days (range 10-17 days) after the transplantation and on one or two more occasions during the following 3 months. Seven cholecystectomized gallstone patients with indwelling T-tubes were used as controls. The bile duct pressure at the level of the xiphoid process in the transplanted group was 7.7 +/- 1.4 cm H2O and in the control group 0.5 +/- 0.8 cm H2O (P < 0.001). The initially increased bile duct pressure after liver transplantation decreased with time (P < 0.05) towards normal during the following 3 months. The raised pressure may increase the risk of bile leakage in the postoperative period.

Distribution of opioidergic, sympathetic and neuropeptide Y-positive nerves in the sphincter of Oddi and biliary tree of the monkey, Macaca fascicularis

The opioidergic, sympathetic and neuropeptide Y-positive innervation of the sphincter of Oddi (common bile duct sphincter and pancreatic duct sphincter), as well as other segments of the extrahepatic biliary tree was studied in the monkey by use of immunohistochemistry. Methionine-enkephalin-positive nerves were seen to innervate the smooth muscle of all portions of the sphincter of Oddi and also local ganglion cells. No methionine-enkephalin-positive nerves could be detected in the common bile duct, pancreatic duct or gallbladder. Tyrosine hydroxylase-positive nerves occurred between smooth muscle bundles and also ran to local ganglion cells as well as along the common bile duct. Neuropeptide Y-positive nerves were observed within smooth muscle of the sphincter of Oddi (all portions), common bile duct, pancreatic duct and gallbladder. No evidence of any differential innervation of the pancreatic duct and common bile duct sphincters could be detected with these markers.

Distension of the gall bladder inhibits sphincter of Oddi motility in humans

Studies in animals have suggested a neural reflex between the gall bladder and the sphincter of Oddi. The aim of this study was to investigate whether sphincter of Oddi motility is altered by distension of the gall bladder in humans. Sphincter of Oddi motility was recorded intraoperatively in 10 patients undergoing elective cholecystectomy for gall stones. The manometry was performed by a triple lumen constantly perfused catheter which was introduced through the cystic duct and positioned across the sphincter of Oddi to record sphincter basal pressure, wave amplitude, and frequency of contractions. In five patients a separate catheter was introduced into the gall bladder after ligation of the cystic duct. This catheter was used to distend the gall bladder. Sphincter of Oddi pressures were measured before, during, and after the distension. In a separate control group of patients (n = 5) basal sphincter of Oddi activity was recorded without distension of the gall bladder. Distension of the gall bladder decreased sphincter of Oddi basal pressure from (mean (SD] 22.8 (8.5) mmHg to 18.6 (6.5) mmHg (p = 0.01, paired t test) and frequency of sphincter of Oddi contractions decreased from 2.6 (1.6) to 1.1 (1.3) contractions/min (p = 0.003, paired t test). The results were significantly different from those of the control group (p less than 0.05, unpaired t test) during the same time period (four minutes). Pulse rate and blood pressure were not affected by the gall bladder distension. The results suggest a local reflex between the gall bladder and the sphincter of Oddi that might be important in the regulation of the pressure within the bile ducts and flow across the sphincter. This reflex is likely to be neurally mediated and injuries to it may be important in the aetiology of postcholecystectomy sphincter of Oddi dysfunction.