Acute and Chronic Feline Pancreatitis - Diagnostic and Therapeutic Challenges
Jörg M. Steiner, Dr.med.vet., PhD, DACVIM, DECVIM-CA
Read the German translation: Akute und chronische Pankreatitis bei der Katze - Diagnostische und therapeutische Überlegungen
The incidence of exocrine pancreatic disorders is almost as high in cats as it is in dogs. In a large retrospective study of necropsy findings 1.3% of 6,504 feline pancreata showed significant pathological lesions. In a more recent study, 115 cats were evaluated at necropsy. At least 3 biopsies were collected from each pancreas and each biopsy was assessed separately for evidence of pancreatitis. The results were very surprising in that only 33% of cats had no evidence of pancreatitis, 15.7% had lesions suggestive of acute pancreatitis, and 60% had evidence suggestive of chronic pancreatitis.
Cats with pancreatitis, even when severe, often present with non-specific clinical signs. In one study of 40 cats with severe pancreatitis the following clinical signs were reported: lethargy (100%), anorexia (97%), dehydration (92%), hypothermia (68%), vomiting (35%), abdominal pain (25%), a palpable abdominal mass (23%), dyspnea (20%), ataxia (15%), and diarrhea (15%). Especially remarkable is the low incidence of vomiting and abdominal pain, both of which are common clinical signs in human and canine pancreatitis patients. Clinical signs in patients with pancreatitis are due to pancreatic autodigestion and inflammation or systemic complications.
Complete blood count and serum chemistry profile often show mild and nonspecific changes. More severe changes can be observed in patients with severe forms of pancreatitis. Serum amylase and lipase activities are of no clinical value for the diagnosis of feline pancreatitis. Radiographic changes seen in some feline patients with pancreatitis include a decreased contrast in the cranial abdomen and displacement of abdominal organs. However, these changes are rather subjective and abdominal radiography is non-specific for feline pancreatitis. Abdominal ultrasound is useful for the diagnosis of pancreatitis in cats if stringent criteria are applied. The sensitivity of abdominal ultrasonography for feline pancreatitis is up to 35% in cats. However, the sensitivity is largely operator-dependant. Changes identified include pancreatic swelling, changes in echogenicity of the pancreas (hypoechogenicity in case of pancreatic necrosis and, less frequently, hyperechogenicity in case of pancreatic fibrosis) and of peripancreatic fat (hyperechogenicity in case of peripancreatic fat necrosis), fluid accumulation around the pancreas, and a mass effect in the area of the pancreas. Abdominal computed tomography is a routine diagnostic procedure in humans suspected of having pancreatitis, but appears to be very insensitive for the diagnosis of pancreatitis in cats.
Trypsin-like immunoreactivity is highly specific for exocrine pancreatic function. However, the sensitivity of serum TLI concentration for pancreatitis in cats is only approximately 30-60% making it a suboptimal diagnostic test for pancreatitis. However, serum fTLI concentration remains the diagnostic test of choice for the diagnosis of feline EPI.
Recently, an assay for the measurement of pancreatic lipase immunoreactivity in cats (fPLI) has been developed and validated. Many different cell types of the body synthesize and secrete lipases. In contrast to catalytic assays for the measurement of serum lipase activity, use of an immunoassay does allow for the specific measurement of lipase originated from the exocrine pancreas. In a group of cats with experimentally induced pancreatitis both serum fTLI and fPLI concentrations did increase initially, but serum fPLI stayed elevated much longer than did serum fTLI concentration, suggesting that serum fPLI concentration is much more sensitive for pancreatitis than serum fTLI concentration.1 In another study of cats with spontaneous pancreatitis, serum fPLI concentration was more sensitive and more specific than serum fTLI concentration or abdominal ultrasonography.2 Thus, serum fPLI concentration is the most sensitive and specific diagnostic test for pancreatitis currently available for cats. Serum fPLI concentration is now being measured with a commercial assay, Spec fPL®.
Traditionally, a pancreatic biopsy has been viewed as the most definitive diagnostic tool for feline pancreatitis. Pancreatic biopsies can be collected during abdominal exploratory or by laparoscopy. The presence of pancreatitis can be easily diagnosed by the gross appearance of the pancreas in many cases, which can then be confirmed by histopathological evaluation of a pancreatic biopsy. However, the absence of pancreatitis can be difficult to prove as pancreatic inflammation is often highly localized. Thus, even if multiple biopsies are being collected, pancreatic inflammation, especially in cases of chronic pancreatitis, may easily be missed. It should also be noted that while a pancreatic biopsy in itself is not associated with many complications many patients with pancreatitis are poor anesthetic risks. Pancreatic cytology may be a better choice to verify pancreatitis in cats. The presence of pancreatic acinar cells in the cytologic preparation confirm that the pancreas has been successfully aspirated and the presence of inflammatory cells confirms pancreatic inflammation. Thus, cytologic evaluation of a fine needle aspirate of the pancreas is very useful in confirming pancreatitis, but, due to the often localized nature of pancreatic inflammation, a lack of inflammatory cells on the pancreatic aspirate does not rule out pancreatitis.
Treatment of the Cause, Supportive Care, and Alimentation
Whenever possible the inciting cause should be removed. However, this may be difficult to accomplish as most cases of feline pancreatitis are idiopathic. A serum chemistry profile should be performed to rule out hypertriglyceridemia and/or hypercalcemia. Exposure to unnecessary drugs, especially those implicated in causing pancreatitis in cats or other species, should be avoided.
Aggressive fluid therapy is the mainstay of supportive therapy in cats with severe pancreatitis. Fluid, electrolyte, and acid-base imbalances need to be assessed, and corrected as early as possible. This is especially important since systemic complications are associated with a worse outcome and many of the systemic complications are difficult to treat once they are established.
The traditional recommendation for any patient with pancreatitis is to give nothing per os for three to four days. This recommendation may be justified in patients that vomit relentlessly. However, there is little evidence to justify this strategy in patients that do not. The issue is complicated further in cats by the fact that cats with pancreatitis often develop hepatic lipidosis. If the patient does not eat voluntarily, the preferred routes of alimentation are a jejunostomy tube or total parenteral nutrition. However, these strategies are impractical in many cases and feeding through esophagostomy, gastrostomy or nasogastric tubes is an acceptable alternative if the patient does not vomit. Regardless of the mode of alimentation, a diet that is relatively low in fat should be chosen.
Abdominal pain is the key clinical sign in human patients with pancreatitis and is recognized in excess of 90% of all human pancreatitis patients. Abdominal pain is only recognized in approximately ¼ of all cats with pancreatitis. However, it is unlikely that abdominal pain occurs less frequently in cats than in humans and it is much more likely that abdominal pain remains unidentified in many cats. Thus, the presence of abdominal pain should be assumed and analgesic drugs are indicated in all cats with pancreatitis. Meperidine, butorphanol tartrate, morphine, fentanyl, or combinations of multiple analgesic drugs can be used in hospitalized patients. Outpatients can be treated with oral butorphanol, tramadol, or a fentanyl patch.
Until recently the choices for antiemetic agents for use in cats with pancreatitis was limited. Metoclopramide, a dopamine inhibitor, was most widely used. However, its effect on splanchnic perfusion remains in question. Fortunately, several other antiemetic agents have become available over the last few years. Dolasetron, is a 5HT3 antagonist and is a very effective antiemetic agent in cats. The injectable formulation of dolasetron can be used for intravenous, subcutaneous, or oral administration and is being used at 0.3-0.6 mg/kg q 12-24 hr. Recently, a new drug, maropitant, an NK1 antagonist has become available in both Europe and the US. Initial experiences in dogs are good, but there is little experience in cats and the drug is currently not licensed for use in cats.
In contrast to human beings, infectious complications of pancreatitis are rare in cats with pancreatitis. Also, even though such complications occur frequently in human pancreatitis patients and are estimated to be responsible for approximately 25-50% of all deaths associated with acute pancreatitis, a clear advantage of antibiotic use has not been demonstrated to date. Therefore, the use of antibiotic agents should be limited to those cases when an infectious complication can be identified or is strongly suspected.
Other Therapeutic Strategies
Studies in dogs suggest that when α2-macroglobulin, one of the scavenger proteins for activated proteases in serum, is depleted death ensues rapidly. Fresh frozen plasma (FFP) and fresh whole blood not only contain α2-macroglobulin, but also albumin, which has many beneficial effects in patients with severe pancreatitis. In clinical trials in human patients with acute pancreatitis there was no benefit of plasma administration. Whether FFP or other blood products are of any benefit in cats with pancreatitis remains to be determined.
Many other therapeutic strategies, such as the administration of antiinflammatory agents, trypsin-inhibitors (e.g., Trasylol), platelet activating factor inhibitors (PAFANTs), dopamine, antacids, antisecretory agents (i.e., anticholinergics, calcitonin, glucagon, somatostatin), or selenium, and peritoneal lavage all have been evaluated in human patients with pancreatitis.
Dopamine has been shown to be useful in preventing progression of pancreatitis when administered to cats within 12 hours of initiating pancreatitis. While this time-limit would preclude dopamine to be effective in routine therapy of spontaneous pancreatitis, patients with pancreatitis that have to undergo anesthesia may benefit from treatment with dopamine during the procedure.
Mild Chronic Pancreatitis
It should also be noted that many feline patients have mild forms of chronic pancreatitis. Often times these patients have concurrent conditions, most notably IBD. Very little is known about appropriate therapy for these animals and management is often limited to evaluation and treatment of the concurrent condition and careful monitoring of the pancreatitis. Serum calcium and triglyceride concentrations should always be evaluated in these patients in order to identify any risk factors that can potentially be addressed therapeutically. Also, the use of low fat diets is recommended in these patients. Over the last two decades a new form of pancreatitis, autoimmune pancreatitis has been described in humans. Autoimmune pancreatitis is characterized by a lymphocytic-plasmacytic infiltration of the pancreas. Human patients with autoimmune pancreatitis respond favourably to the administration of corticosteroids. Recently, several clinicians have started to cautiously treat feline patients with chronic pancreatitis with corticosteroids and have found this treatment strategy to be beneficial in a portion of cases.
The prognosis cats with pancreatitis is directly related to disease severity, extent of pancreatic necrosis, occurrence of systemic and pancreatic complications, duration of the condition, and the presence of concurrent disease.
1. Williams DA, Steiner JM, Ruaux CG, Zavros N. Increases in serum pancreatic lipase immunoreactivity (PLI) are greater and of longer duration than those of trypsin-like immunoreactivity (TLI) in cats with experimental pancreatitis. J.Vet.Int.Med. 2003;17:445-446;
2. Forman MA, Marks SL, De Cock HEV, et al. Evaluation of serum feline pancreatic lipase immunoreactivity and helical computed tomography versus conventional testing for the diagnosis of feline pancreatitis. J Vet Int Med 2004; 18:807-815;
3. Steiner JM. Exocrine pancreas. In: Steiner JM. ed. Small animal gastroenterology. Hannover: Schlütersche, 2008;283-306.