Case Study: Feline Pancreatitis


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Feline Pancreatitis Figure 1
Figure 1

A wavy, ‘spastic’ appearance of the duodenum, thought to be secondary to pancreatitis.

Feline Pancreatitis Figure 2
Figure 2

Enlarged, irregular, hypoechoic pancreatic body with surrounding hyperechoic mesentery imaged in a sagittal plane, caudal to the gall bladder and cranial and dorsal to the duodenum.

Feline Pancreatitis Figure 3
Figure 3

Hypoechoic left pancreatic limb with surrounding hyperechoic mesentery imaged in a sagittal plane, caudal to the stomach and cranial to the left kidney.

Feline Pancreatitis Figure 4
Figure 4

Case 2: Enlarged, hypoechoic left pancreatic limb seen just dorsal to the stomach. The pancreatic duct was prominent, and measured 0.20 cm.

Feline Pancreatitis Figure 5
Figure 5

Case 2: Enlarged, hypoechoic left pancreatic limb seen just dorsal to the stomach. The pancreatic duct was prominent, and measured 0.20 cm.


Case Studies

Case 1: A five-year-old neutered male Domestic Shorthair cat was presented with an acute history of anorexia and vomiting. Physical examination revealed a painful cranial abdomen. A complete blood count and blood chemistry profile were normal, and abdominal radiographs were unremarkable. Abdominal ultrasound revealed a spastic duodenum (Figure 1), an enlarged, irregular, hypoechoic pancreatic body (Figure 2) and a hypoechoic left pancreatic lobe (Figure 3), as well as hyperechoic surrounding mesentery which surrounded the body and left pancreatic lobe. A diagnosis of pancreatitis was made, and he responded to intravenous fluid therapy, famotidine and pain medication.

Case 2: A twelve-year-old spayed female Domestic Longhair cat was presented with a one week history of anorexia and vomiting. Physical examination was unremarkable. A complete blood count and blood chemistry profile revealed an elevated ALT (15 x normal). Abdominal ultrasound revealed an enlarged, hypoechoic, left pancreatic limb and a prominent pancreatic duct (Figures 4 and 5). The liver parenchyma, gall bladder and common bile duct were normal. A feline pancreatic lipase immunoreactivity level was elevated. She responded to intravenous fluid therapy, famotidine, metronidazole, enrofloxacin and denosyl. Further workup to rule out concurrent hepatic disease was declined.

Did these cats truly have pancreatitis? Was there concurrent disease present that responded to the same medical therapy? Anorexia and vomiting in a cat are vague symptoms which can have several causes. Gastritis, inflammatory bowel disease, gastrointestinal neoplasia, foreign body ingestion, pancreatitis, hepatic disease, renal disease and are all likely differential diagnoses.

Pancreatitis has recently become a more common diagnosis in cats, but its true prevalence is not known. Historically, feline pancreatitis was thought to have a low incidence, most likely due to the vague clinical signs that result, the common presence of concurrent diseases and the lack of adequately sensitive and specific diagnostic tests to detect the disease.

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Case Discussion

Etiology and Classification of Feline Pancreatitis

As in dogs, feline pancreatitis occurs as a result of autodigestion of pancreatic tissue by premature intracellular activation of digestive enzymes such as proteases and phospholipases. This results in local cell damage as well as systemic release of inflammatory cytokines. In cats, 90% of the cases of pancreatitis diagnosed are idiopathic. Pancreatitis in the cat can be acute or chronic as in the dog, but the chronic form is thought to be more common in the cat, and the acute form more common in the dog. Both the acute and the chronic forms can be mild, moderate or severe, further demonstrating the wide spectrum of disease that feline pancreatitis constitutes. Many cases exist concurrently with inflammatory bowel disease, hepatic lipidosis and cholangiohepatitis. Concurrent intestinal and biliary neoplasia has also been reported.

Clinical Presentation and Blood Work Findings

Pancreatitis can be incredibly challenging to definitively diagnose in cats. The clinical signs in a cat with pancreatitis are more vague than those typically seen in a dog with pancreatitis, with lethargy and anorexia most commonly reported. Abdominal pain and vomiting are seen in only 25-52% of affected cats. A complete blood count and blood chemistry profile can be normal, or the findings can be nonspecific. Anemia, leukocytosis, elevation of hepatic enzymes and bilirubin, hypoalbuminemia and hypocalcemia can be seen. Amylase and lipase levels are not useful in diagnosing pancreatitis in the cat.

A fairly new assay for fPLI (feline pancreatic lipase immunoreactivity), has been shown to have a sensitivity of 67% and specificity of 91% for diagnosing feline pancreatitis. A similar assay for fTLI (feline trypsin-like immunoreactivity) has been shown to have a lower sensitivity (28%) and specificity (82%). Both assays are run at the GI lab at Texas A & M (www.cvm.tamu.edu/gilab). Histopathology may still be considered to be the gold standard method of diagnosing pancreatitis, but surgery and biopsy may not be warranted or practical in many cases, and as well, gross examination of the pancreas may not identify the regions of the gland affected, making it difficult to obtain representative biopsies.

Radiography and Computed Tomography

Abdominal radiographic findings are nonspecific, and may be normal, may show decreased intraabdominal contrast, dilated bowel loops, or there may be suggestion of a cranial abdominal mass. Thoracic radiographs may reveal pleural effusion. Computed tomography, which is very sensitive and specific in humans, has low sensitivity (20%) in detecting feline pancreatitis.

Abdominal Ultrasound and Pancreatitis

Abdominal ultrasonography is commonly performed on cats suspected to have pancreatitis.

Thorough evaluation of the feline pancreas involves identification of the known landmarks which surround the organ. The right limb is dorsomedial to the duodenum, the pancreatic body is caudal to the gall bladder and pyloric-duodenal, and the left limb is dorsocaudal to the stomach, cranial to the transverse colon, medial to the spleen and cranial to the left kidney. The portal vein may be seen dorsal to the left limb and body of the pancreas. The pancreatic duct is most consistently seen in the pancreatic body and left pancreatic limb and is centrally located. Visualization of the pancreatic duct may assist in localizing pancreatic parenchyma. In most cats, the pancreatic duct fuses with the common bile duct, and then opens into the major duodenal papilla. Doppler evaluation can be used to confirm that the vessel is nonvascular.

The normal feline pancreas has a smooth and homogeneous echotexture, and has been reported to be isoechoic to the surrounding mesenteric fat, as well as isoechoic to the liver and hypoechoic to the surrounding mesentery. The echogenicity of the feline pancreas does not appear to increase with age or obesity. The diameter of the normal feline pancreatic duct has a wide range which likely overlaps with that of cats with pancreatitis. A very slight increase in the pancreatic duct diameter within the pancreatic body has been observed with increasing age.

Normal feline pancreatic size (from Etue et al., 2001 and Larson et al., 2005)

Pancreatic structure

Mean width (mm)

Width range (mm)

Right limb

4.5

2.8-5.9

Body

5.6-6.6

3.3-9.5

Left limb

5.4

2.6-9.5

Pancreatic duct

0.8-1.1

0.5-2.5

The sensitivity of ultrasound to detect pancreatitis has been reported in different studies to be 11%, 24%, 35% and 67%. The specificity of ultrasound was evaluated in one study and was found to be 88% in eight clinically normal cats, and 33% in three symptomatic cats that had a histopathologically normal pancreas. The sensitivity and specificity of ultrasound in diagnosing pancreatitis depends on the ultrasonographic criteria considered to confirm the diagnosis, as well as the degree of patient cooperation, operator skill and imaging equipment used. Ultrasonographic findings considered to indicate that pancreatitis existed vary somewhat between studies and include:

  • Pancreatic enlargement
  • Hypoechoic parenchyma
  • Hyperechoic and course parenchyma
  • Irregular gland contour
  • Pancreatic mass
  • Hyperechoic surrounding mesentery
  • Pancreatic duct dilation
  • Pseudocyst formation
  • Common bile duct dilation
  • Mesenteric lymphadenopathy
  • Peritoneal effusion
  • Gastric or duodenal wall thickening.

Concurrent disease may likely cause some of the above changes, such as mesenteric lymphadenopathy, peritoneal effusion, common bile duct dilation and gastrointestinal wall thickening.

The ultrasound findings report above may not be specific for pancreatitis, and cytology, histopathology and serial ultrasound examinations are recommended before a definitive diagnosis is made. Exocrine pancreatic neoplasia (i.e. adenocarcinoma) is thought to be rare in cats, but is a possible differential diagnosis in cases thought to have pancreatitis. Clinical signs in cases of exocrine pancreatic neoplasia are nonspecific, and similar to those seen with pancreatitis. Some cases have been reported to have paraneoplastic alopecia. Ultrasound findings reported in cases of exocrine pancreatic neoplasia include the presence of free abdominal fluid, a mass in the pancreas, or nodules in the liver or spleen. In some cases, the ultrasound exam can be normal. The diagnosis of neoplasia should be confirmed with ultrasound-guided fine-needle aspirates, ultrasound-guided biopsies or surgical biopsies. The prognosis for these cats is considered to be poor, as there is likely to be metastatic disease at the time of diagnosis.

Pancreatic nodular hyperplasia is another possible differential diagnosis for the ultrasound changes reported with pancreatitis. Pancreatic nodular hyperplasia is a common, benign finding in cats that usually does not result in clinical signs. The condition is often an incidental finding during a post mortem exam. Ultrasound of affected cats typically reveals multiple, hypoechoic nodules and pancreatic enlargement. Pancreatic duct dilation can also be seen, as well as extrahepatic biliary obstruction. In one study (Hecht et al, 2007), the presence of a single mass measuring greater than 2 cm was the only finding that could reliably distinguish cats with pancreatic hyperplasia from those with neoplasia. In that same study, the presence of multiple nodules was more common with hyperplasia, but was also seen in cats with adenocarcinoma.

Treatment and Prognosis

Treatment recommendations for feline pancreatitis include supportive fluid therapy, treatment of abdominal pain and cobalamin supplementation if testing reveals a deficiency. Antibiotics and H2-receptor histamine antagonists may or may not be of benefit. In severe, acute pancreatitis, plasma or whole blood therapy is indicated. If chronic pancreatitis exists with inflammatory bowel disease, corticosteroid therapy may be of benefit. In humans, therapy with exogenous pancreatic enzymes results in less abdominal pain. If liver fluke infection is suspected, praziquantal therapy should be given. Low fat diet can be offered, although the role of high fat diet and pancreatitis is not well established in cats. As hepatic lipidosis can occur concurrently in cats with pancreatitis, force feeding or tube feeding is indicated in anorexic cats that are not vomiting. A jejunostomy tube is another feeding option to consider. The prognosis for cats with pancreatitis is quite variable, and depends on the severity of the disease. Acute pancreatitis cats have a poor prognosis and their clinical condition can deteriorate rapidly. Chronic cases tend to have a much better prognosis.

Summary

Feline pancreatitis presents a great diagnostic challenge. The combination of history and physical examination findings along with fairly sensitive and specific tests such as the fPLI assay and abdominal ultrasound may help to confirm the diagnosis as well as identify concurrent disease. The sensitivity of ultrasound is getting higher with better imaging equipment and increasing operator experience. The incidence of false positive findings identified with ultrasound needs to be investigated further.

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References

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