Review of feline pancreatitis part one: the normal feline pancreas, the pathophysiology, classification, prevalence and aetiologies of pancreatitis

Perioperative outcomes in dogs and cats undergoing pancreatic surgery: 81 cases (2008-2019)

OBJECTIVES

To identify and describe the type and frequency of perioperative factors in dogs and cats undergoing pancreatic surgery under referral care.

METHODS

Medical records from a small animal surgical referral practice were retrospectively reviewed to identify dogs and cats that underwent pancreatic surgery between 2008 and 2019. Inclusion criteria included complete medical record, histopathology results and follow-up of at least 14 days postoperatively or until death. Variables collected included signalment, history, presenting complaint, preoperative diagnostic results, intraoperative complications, surgical findings/procedures, postoperative complications and histopathology results. Cases were excluded if pertinent information or a histopathology report was missing from the medical record. The frequency of these variables was reported.

RESULTS

There were 81 client-owned animals identified that met the inclusion criteria (57 dogs and 24 cats). The most common pancreatic procedure performed in dogs was partial pancreatectomy 63.2% (36/57) and in cats was pancreatic biopsy 62.5% (15/24). The most common histologic diagnosis in dogs was pancreatic islet cell carcinoma 50.9% (29/57) and in cats was pancreatitis 41.7% (10/24). The overall mortality rate was 13.6% (11/81), with a 10.5% (6/57) mortality rate in dogs and a 20.8% (5/24) mortality rate in cats.

CLINICAL SIGNIFICANCE

In this series of dogs and cats, pancreatic surgery under referral care carried a low to moderate mortality rate.

Feline abdominal ultrasonography: What's normal? What's abnormal? The pancreas

PRACTICAL RELEVANCE

Abdominal ultrasound plays a vital role in the diagnostic work-up of many cats presenting to general and specialist practitioners. Ultrasound examination of the pancreas is a vital part of the investigation into feline pancreatic disease.

CLINICAL CHALLENGES

Despite ultrasonography being a commonly used modality, many practitioners are not comfortable performing an ultrasound examination or interpreting the resulting images. Even for the experienced ultrasonographer, differentiating between incidental findings such as nodular hyperplasia and pathological changes such as neoplasia can be challenging.

AIM

This review, part of an occasional series on feline abdominal ultrasonography, discusses the ultrasonographic examination and appearance of the normal and diseased pancreas. Aimed at general practitioners who wish to improve their knowledge of and confidence in feline abdominal ultrasound, this review is accompanied by high-resolution images and videos available online as supplementary material.

EQUIPMENT

Ultrasound facilities are readily available to most practitioners, although use of ultrasonography as a diagnostic tool is highly dependent on operator experience.

EVIDENCE BASE

Information provided in this article is drawn from the published literature and the author's own clinical experience.

Histopathology and Feline Pancreatic Lipase Immunoreactivity in Inflammatory, Hyperplastic and Neoplastic Pancreatic Diseases in Cats

The most common pancreatic diseases in cats are pancreatitis and exocrine pancreatic insufficiency (EPI). Non-invasive methods, such as serological quantification of feline pancreatic lipase immunoreactivity (fPLI), are often used in the diagnosis of pancreatitis. Previous studies have compared fPLI concentrations with histopathology, considered to be the gold standard for diagnosis of feline pancreatitis. However, fPLI concentrations in cats suffering from pancreatic tumours were rarely described. The aim of the present study was to determine the sensitivity and specificity of an in-house enzyme-linked immunosorbent assay (ELISA) for the quantification of fPLI in serum samples based on histopathological findings in cats diagnosed with various pancreatic diseases. Pancreatic biopsy samples from 80 cats were included. Five groups were defined on the basis of pancreatic histopathology: group 1, normal pancreas; group 2, nodular hyperplasia; group 3, mild pancreatitis; group 4, marked (moderate/severe) pancreatitis; and group 5, pancreatic neoplasia. Serum samples from all cats were tested by fPLI ELISA (<3.6 μg/l normal, 3.6-5.3 μg/l questionable, >5.3 μg/l pancreatitis). In group 1 (n = 19), serum fPLI values were within the reference interval in 74% of cases and in group 2 (n = 9) in 78%. Cats with mild pancreatitis (n = 23), marked pancreatitis (n = 11) and pancreatic neoplasms (n = 18) had significantly increased fPLI concentrations compared with group 1 (P = 0.004/0.001/≤0.0001). Cats with nodular hyperplasia had significantly lower fPLI values than cats with marked pancreatitis (P = 0.048) or tumours (P = 0.002). Serum fPLI concentrations in group 3 were <3.6 μg/l (n = 6), 3.6-5.3 μg/l (n = 4) and >5.3 μg/l (n = 13). Calculated test sensitivity for mild pancreatitis was fPLI >3.5 μg/l: 73.9% and fPLI >5.3 μg/l: 56.5%. In group 4 (n = 11), seven of nine cats (77.8%) with marked purulent pancreatitis had elevated fPLI. In group 4, a sensitivity of 81.8% was detected for fPLI >3.5 μg/l and 63.6% for fPLI >5.3 μg/l. Two cats with marked non-purulent pancreatitis had elevated fPLI, while two cats with marked purulent pancreatitis had normal fPLI values (<3.6 μg/l). In group 5, one cat with pancreatic adenoma and one with pancreatic acinar carcinoma had normal fPLI concentrations. The other cats with pancreatic adenoma (solid, n = 1; cystic, n = 4) or carcinoma (solid, n = 9; cystic, n = 2) had elevated or high fPLI values (4.1 to >40 μg/l, median 21.2 μg/l), probably caused by additional inflammation. The results of the present study confirm the importance of detailed histopathological characterization for the interpretation of clinical signs and fPLI values in feline pancreatitis. Primary pancreatic neoplasms may also lead to elevated fPLI concentrations as there is concurrent pancreatitis in most cases. However, severe pancreatic diseases, such as chronic non-purulent pancreatitis or tumours without inflammation, may result in normal fPLI values.

A retrospective study of 157 hospitalized cats with pancreatitis in a tertiary care center: Clinical, imaging and laboratory findings, potential prognostic markers and outcome

BACKGROUND

Pancreatitis in cats (FP) has been increasingly diagnosed in recent years, but clinical studies of large numbers of affected cats are scarce.

OBJECTIVES

To describe a large cohort of cats with FP requiring hospitalization.

ANIMALS

One hundred and fifty-seven client-owned cats.

METHODS

Retrospective study, including cats diagnosed with pancreatitis based on sonographic evidence, positive SNAP feline pancreatic lipase immunoreactivity test results, increased 1,2-o-dilauryl-rac-glycerol-glutaric Acid-(6'-methylresorufin ester)-lipase activity, histopathology, or some combination of these.

RESULTS

One-hundred and twenty-two cats (77.7%) survived to discharge. Median time from onset of clinical signs to presentation was longer (P = .003) in nonsurvivors. Causes of FP included recent general anesthesia, trauma, hemodynamic compromise, and organophosphate intoxication, but most cases (86.6%) were idiopathic. Ultrasonographic findings consistent with pancreatitis were documented in 134 cats, including pancreatomegaly (81.3%), decreased (31.3%), or increased (14.9%) pancreatic echogenicity, extra-hepatic biliary tract dilatation (24%), and increased peri-pancreatic echogenicity (13%). Lethargy (P = .003), pleural effusion (P = .003), hypoglycemia (P = .007), ionized hypocalcemia (P = .016), azotemia (P = .014), parenteral nutrition administration (P = .013), and persistent anorexia during hospitalization (P = .001) were more frequent in nonsurvivors, whereas antibiotics were more frequently administered to survivors (P = .023). Nevertheless, when Bonferroni's correction for multiple comparisons was applied, none of the variables was statistically significant.

CONCLUSIONS AND CLINICAL IMPORTANCE

Previously unreported, clinically relevant, potential prognostic factors, including hypoglycemia, azotemia, parenteral nutrition, and withholding antibacterial treatment were identified in this exploratory study. These preliminary results should be examined further in confirmatory studies.

Can clinical signs, clinicopathological findings and abdominal ultrasonography predict the site of histopathological abnormalities of the alimentary tract in cats?

OBJECTIVES

Many cats with gastrointestinal signs have coexisting abnormalities in the intestine, liver and pancreas. Investigations typically involve clinicopathological tests, diagnostic imaging and biopsy, either at coeliotomy or by non-invasive means. While exploratory coeliotomy enables all organs to be sampled simultaneously, it is invasive and might not be necessary. The aim of the current study was to assess the performance of preliminary clinical information in predicting the histopathological presence of abnormalities in alimentary tract organs in cats.

METHODS

The records of 38 cats with alimentary tract signs, which had ultimately undergone exploratory coeliotomy and surgical biopsy, were reviewed. The clinical signs, clinicopathological findings, diagnostic imaging findings and histopathology results were reviewed.

RESULTS

On histopathological analysis, lesions were detected in 29/37 (78%) liver biopsies, in 29/35 (83%) gastrointestinal biopsies and in 17/37 (46%) pancreatic samples, the majority of which were inflammatory in nature. Clinical signs were generally poor markers of the presence of lesions in the alimentary tract. Further, while liver enzyme activity was relatively specific (88-100%) for detecting histopathological abnormalities in the liver, sensitivity was poor (11-50%). Pancreatic histopathological abnormalities were present in 1/3 of the cats with a positive pancreas-specific lipase result, and in 6/8 cats with a negative result. While relatively specific (57-100%) for both intestinal (57-100%) and hepatic (71-80%) histopathological abnormalities, abdominal ultrasonography lacked sensitivity for both organs (intestine 50-80%; liver 20-25%). In contrast, ultrasonography was relatively sensitive (50-80%), but not specific (17-22%) for detecting pancreatic lesions.

CONCLUSIONS AND RELEVANCE

Clinical signs, and clinicopathological and ultrasonographic abnormalities lack precision for hepatic and pancreatic histopathological lesions in cats with alimentary tract signs, and cannot reliably predict from which organs biopsies should be collected. Arguably, therefore, exploratory coeliotomy is necessary to determine the site of histopathological abnormalities in feline alimentary tract disorders.

Pancreatitis in cats

Practical relevance:

Pancreatitis is a frequent finding in cats, the chronic form being more common than the acute form. Despite the large number of diseases or conditions that may be associated with feline pancreatitis, in most cases no cause is diagnosed and the pancreatitis is said to be idiopathic. The chronic form can be mild and asymptomatic, and has a high prevalence in apparently healthy cats. This has generated debate concerning the clinical significance of chronic feline pancreatitis. However, several reports have demonstrated the severity of clinical signs in certain forms of acute feline pancreatitis, while other studies have reported a strong association between chronic pancreatitis and the development of comorbidities such as hepatic lipidosis, diabetes mellitus, inflammatory bowel disease or exocrine pancreatic insufficiency. This suggests that feline pancreatitis should not be overlooked.

Clinical challenges:

Diagnosis of feline pancreatitis is complicated by the non-specific clinical signs and poor diagnostic value of basic biochemistry and haematology or imaging techniques. Development of a feline-specific pancreatic lipase immunoassay has improved our diagnostic ability in the past decade, but may have more limited application for mild and chronic forms of pancreatitis. Moreover, histopathology (the ‘gold standard’ diagnostic test) can be associated with false-negative results due to multifocal distribution of lesions or mild forms of the disease. With respect to treatment, it is important to take into account the idiosyncrasies of the feline species when considering medical therapies.

Evidence base:

This article reviews the literature on feline pancreatitis, focusing on the different forms and their relative clinical significance, while explaining difficulties inherent in the diagnosis of this disease. An overview of current recommendations for the management of cats with pancreatitis is also provided.

Pancreatitis in cats

Pancreatitis was considered a rare disease in the cat until a couple of decades ago when several retrospective studies of severe acute pancreatitis were published. It was apparent that few of the diagnostic tests of value in the dog were helpful in cats. With increasing clinical suspicion, availability of abdominal ultrasonography, and introduction of pancreas-specific blood tests of increasing utility, it is now accepted that acute pancreatitis is probably almost as common in cats as it is in dogs, although the etiology(s) remain more obscure. Pancreatitis in cats often co-exists with inflammatory bowel disease, less commonly with cholangitis, and sometimes with both. Additionally, pancreatitis may trigger hepatic lipidosis, while other diseases, such as diabetes mellitus, may be complicated by pancreatitis. Therapy is similar to that used in dogs, with added emphasis on early nutritional support to prevent hepatic lipidosis. Less is known about chronic pancreatitis than the acute form, but chronic pancreatitis is more common in cats than it is in dogs and may respond positively to treatment with corticosteroids.

Characteristics and outcomes in surgical management of severe acute pancreatitis: 37 dogs (2001-2007)

OBJECTIVE

Describe clinical characteristics and outcomes associated with canine patients undergoing surgical intervention for treatment of acute pancreatitis.

DESIGN

Retrospective outcome study from 2001 to 2007.

ANIMALS

Thirty-seven dogs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The following data were collected for dogs who underwent surgical intervention in the course of treatment for severe acute pancreatitis: preoperative clinicopathologic and physical data, ultrasonographic findings, surgical procedure detail, histopathologic findings, and transfusion requirements. The survival rate was 80.8% in dogs with extrahepatic biliary obstruction, 64.3% in dogs undergoing necrosectomy, and 40.6% with pancreatic abscess. Overall survival was 63.6%. Surgical complications included intraoperative and postoperative hemorrhage in 12 dogs, postoperative development of diabetes mellitus in 3 dogs, exocrine pancreatic insufficiency in 1 dog, and bacterial peritonitis in 2 dogs.

CONCLUSION

Surgical intervention and aggressive postoperative care may be pursued in select dogs with severe acute pancreatitis. In dogs with extrahepatic biliary obstruction secondary to acute pancreatitis, surgical intervention may be associated with a good prognosis whereas dogs with pancreatic abscess formation may have a more guarded prognosis.

AGE-RELATED CHANGES IN THE ULTRASOUND APPEARANCE OF THE NORMAL FELINE PANCREAS

In humans, pancreatic hyperechogenicity and duct dilation are reported as normal aging changes. Similar changes have been reported with pancreatitis in the cat. We attempted to determine if aging changes occur in the ultrasound appearance of the normal feline pancreas. The pancreas of 84 normal (based on history, physical exam, biochemical profile, and feline trypsin-like immunoreactivity and pancreatic lipase immunoreactivity concentrations) cats of varying ages was scanned. Pancreatic width at the left limb and body, pancreatic duct diameter at left limb and body, and pancreatic echogenicity compared with liver and surrounding fat were noted and compared with age and body weight. Lower and upper limits of the 95% reference intervals for pancreatic left limb width were 2.6 and 9.5 mm, and 3.5 and 8.5 mm for the pancreatic body width. There was no significant difference in pancreatic width between the left limb and body. Lower and upper limits of the 95% reference interval for the diameter of the pancreatic duct at the left limb and body were similar, and were 0.65 and 2.5 mm. There was a weak but significant linear correlation between pancreatic duct diameter and age, with increasing pancreatic duct diameter with increasing age. There was no correlation of pancreatic width with age, and no correlation of pancreatic echogenicity with age or body weight. Based on this study, feline pancreatic size and echogenicity do not change with age. Pancreatic duct diameter increases slightly with age and should not be used as a sole indicator of pancreatitis in the geriatric cat.

Underlying cause, pathophysiologic abnormalities, and response to treatment in cats with septic peritonitis: 51 cases (1990-2001)

OBJECTIVE

To determine the underlying cause, pathophysiologic abnormalities, and response to treatment in cats with septic peritonitis and identify differences between cats that survived following treatment and cats that did not survive despite treatment.

DESIGN

Retrospective study.

ANIMALS

51 cats with septic peritonitis.

PROCEDURE

Medical records were reviewed for clinical findings; results of clinicopathologic testing, microbial culture, and radiography; diagnosis; treatment; and outcome.

RESULTS

Signs of pain during palpation of the abdomen were reported for only 29 of 47 (62%) cats. Eight (16%) cats had relative bradycardia (heart rate < 140 beats/min). The most commonly isolated organisms included Escherichia coli, Enterococcus spp, and Clostridium spp. The most common cause of peritonitis was gastrointestinal tract leakage (24 cats). No definitive source could be identified in 7 cats. Treatment, including exploratory surgery, was pursued in 23 cats, of which 16 (70%) survived and were discharged. There were no significant differences between survivors and nonsurvivors in regard to heart rate, age, rectal temperature, serum lactate concentration, WBC count, PCV, blood glucose concentration, or serum albumin concentration.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that clinicopathologic abnormalities and outcome in cats with septic peritonitis are similar to those reported for dogs. However, certain features may be unique, including an absence of signs of pain during abdominal palpation, relative bradycardia, and apparent spontaneous peritonitis in some cats.

Exocrine Pancreatic Neoplasia in the Cat: A Case Series

Eight cases of feline pancreatic adenocarcinoma and two cases of pancreatic adenoma were reviewed. The adenomas were incidental findings. Most cats with adenocarcinomas had anorexia (75%) and vomiting (63%), while 38% had abdominal pain, a palpable abdominal mass, and/or jaundice. Diagnostic abnormalities included leukocytosis, hyperglycemia, increased alanine aminotransferase activity, poor serosal detail on abdominal radiography, and an abdominal mass effect on ultrasonography. The majority of cats with carcinomas had metastases (mostly to liver, lung, and small intestine), and all were euthanized or died within 7 days of diagnosis. Clinically, feline pancreatic carcinoma may be difficult to distinguish from feline pancreatitis.

Pancreatolithiasis and Pancreatic Pseudobladder Associated With Pancreatitis in a Cat

Pancreatolithiasis has been documented to occur naturally in humans and cattle. It has been associated with chronic pancreatitis in humans, and, when found, it may signify the presence of chronic pancreatic disease. This is the first report of a case involving a cat that had both an apparent obstruction with pancreatolithiasis as well as concurrent evidence of chronic pancreatic changes on histopathological evaluation. Additionally, this case documents the presence of a suspected congenital abnormality of a feline exocrine pancreas.