From Diagnosis to Treatment: A Case of Canine Acute Pancreatitis

Sidney, a 10-year-old female spayed cocker spaniel, presented with a 2-day history of lethargy, anorexia, and diarrhea.

History & Physical Examination

Sidney had a history of chronic keratoconjunctivitis sicca that was treated with topical cyclosporine.

Two days before presentation, Sidney began refusing to eat and became lethargic. At that time, she was taken to her primary care veterinarian; basic blood analysis and urinalysis were performed (specific results not available). The urinalysis results indicated a urinary tract infection, and Sidney received amoxicillin/clavulanic acid.

However, after initiation of antibiotic therapy, Sidney had loose stools that contained gelatinous red clumps. At this point, her primary care veterinarian referred her for further diagnostics and treatment.

Sidney’s physical examination findings on presentation to the referral facility are listed in Table 1. Differential diagnoses based on history, clinical signs, and physical examination findings are outlined in Table 2.

 

Diagnostic Approach

In addition, 3-view abdominal radiographs were taken to rule out a gastrointestinal (GI) foreign body and other obvious abdominal organ-related diseases. On the basis of abdominal radiography results, abdominal ultrasonography with abdominocentesis was performed. The collected abdominal fluid was prepared for analysis and cytology.

CBC Results

The number of red blood cells (RBCs) was normal at first and mildly decreased later. The normal number of RBCs upon presentation may have been related to the mild dehydration. With aggressive fluid therapy, the patient became mildly anemic due to a dilutional effect on the number of RBCs.

Moderate thrombocytopenia together with the coagulation panel results indicated disseminated intravascular coagulation (DIC). DIC can occur in patients with severe pancreatitis and other serious systemic diseases, such as sepsis due to peritonitis or neoplasia.

Serum Biochemical Profile Results

Decreases in total protein and albumin are common in dogs with severe acute pancreatitis and other causes of peritonitis due to albumin loss into the peritoneal effusion. However, the pathogenesis may vary and there are many other differential diagnoses for decreased albumin, including:

• Decreased production due to pregnancy, lactation, intestinal malabsorption, malnutrition, cachexia secondary to neoplasia, exocrine pancreatic insufficiency, or chronic liver disease
• Accelerated loss due to protein losing enteropathy or nephropathy, hemorrhage, severe exudative skin disease, burns, intestinal parasitism, or high-protein effusions
• Acute tissue injury/inflammation as a negative acute phase reactant (eg, pancreatitis, peritonitis).

The mildly decreased total calcium was attributed to hypoalbuminemia, while the mildly decreased magnesium may have been caused by decreased GI absorption.

The mild to moderate increase in alkaline phosphatase activity was most likely due to cholestasis secondary to pancreatitis, based on history and other findings. This finding is common in dogs with acute pancreatitis. Elevated alkaline phosphatase activity in adult dogs can also be caused by:

• Intrahepatic or extrahepatic cholestasis
• Endogenous or exogenous glucocorticoids or other drugs
• Bone lesions (lytic or proliferative)
• Active bone resorption (primary or secondary hyperparathyroidism).

Urinalysis & Urine Culture Results

Isosthenuria (urine specific gravity, 1.012) with mild proteinuria (sulfosalicylic acid test result, 1+) was present but, otherwise, unremarkable. Isosthenuria may have resulted from IV fluid administration during hospitalization.

The urine culture was negative; this result may have been affected by the antibiotic therapy initiated 2 days prior to presentation. The antibiotic was discontinued during hospitalization because there was no evidence of a urinary tract infection and the diarrhea was considered a potential side effect of antibiotic therapy.

Coagulation Panel Results

DIC was indicated on the basis of thrombocytopenia, mildly prolonged prothrombin time and partial thromboplastin time, decreased antithrombin III, and increased D-dimers, but there were no clinical signs of thrombosis or bleeding.

Canine cPL Result

• Abnormal SNAP cPL (Figure 1) indicated a value in the gray zone (200–400 mcg/L) or one consistent with pancreatitis (> 400 mcg/L).

• Follow-up Spec cPL (idexx.com) was 1678 mcg/L (reference range, ≤ 200 mcg/L) and, thus, consistent with pancreatitis.

Abdominal Radiographs

Loss of serosal detail in the right cranial abdomen was consistent with peritoneal effusion, while a mildly enlarged and rounded liver was consistent with hepatic venous congestion, hyperadrenocorticism, diabetes mellitus, neoplasia, or an acute inflammatory hepatopathy.

Considering the patient’s clinical signs and radiographic findings, the top differential diagnosis was pancreatitis with extrahepatic biliary obstruction. However, inflammatory hepatopathy, such as a gallbladder mucocele with possible bile peritonitis or hepatic neoplasia with hemorrhagic or neoplastic effusion, were also considered differential diagnoses.

Abdominal Ultrasonography

Ultrasonographic findings (Figure 2) included:

• Moderate volume of anechoic free abdominal fluid, with a few echoes throughout, consistent with modified transudate or possibly exudate
• Enlarged hypoechoic pancreas
• Hyperechoic mesenteric fat, consistent with saponification of fat secondary to inflammation
• Enlarged liver with multiple hyperechoic nodules likely suggesting a regenerative process, but neoplasia could not be excluded
• Undulating, but not plicated, duodenum
• Periportal, pancreatic, and gastric lymph node enlargement.

These findings were most likely suggestive of pancreatitis, with no evidence of gallbladder mucocele or obvious pancreatic neoplasia. However, hepatic neoplasia could not be completely ruled out. Further diagnostic workup for possible neoplasia and other causes of enlargement of several abdominal lymph nodes was refused by the client.

Analysis & Cytology of Abdominal Fluid

Findings from abdominocentesis indicated a modified transudate (total protein, 2.7 g/dL; total nucleated cell counts, 10,195/mcL). Cytology showed marked nondegenerative neutrophilic inflammation and mild histiocytic inflammation.

Diagnosis

Acute pancreatitis was diagnosed based on history, physical examination findings, nonspecific findings on general blood analysis, abnormal pancreatic lipase immunoreactivity (cPLI) based on abnormal SNAP cPL and/or increased Spec cPL results, abdominal radiographs, and ultrasonographic findings.

Therapeutic Approach

Therapy for Acute Pancreatitis

• IV fluid therapy: Lactated Ringer’s solution was initiated and adjusted on the basis of regular monitoring of hydration status.
• Analgesia: Lidocaine (25 mcg/kg/H) was initially given IV as a constant rate infusion (CRI), with buprenorphine added (0.4 mg IV Q 8 H). On day 3 of hospitalization, fentanyl (3 mcg/kg/H IV CRI) was started, with lidocaine and buprenorphine discontinued.
• Nausea control: Maropitant was initially administered alone at 10.4 mg SC Q 24 H; ondansetron was added on day 2 at 3.12 mg IV Q 12 H.
• Nutritional support: Attempts were made to feed several types of commercially available low fat diets for the first 2 days of hospitalization, but Sidney was not interested in eating and seemed to be nauseated despite anti-emetic treatment. On day 3 of hospitalization, a nasoesophageal tube was placed, but the patient pulled it out. On day 4, syringe feeding with canine CliniCare (abbott.com) was tolerated. On day 5, the patient began to eat boiled chicken; CliniCare was adjunctively administered to meet daily energy requirements.

Therapy for Early Stage DIC

Fresh frozen plasma (20 mL/kg IV) was administered over 4 hours to supplement coagulation factors on days 1, 5, and 6. Clopidogrel (18.75 mg PO Q 24 H) was administered to inhibit platelet activity.

Additional Supportive Care

On day 7 of hospitalization, all IV fluids and medications were discontinued and Sidney was discharged on oral medications, including tramadol (25 mg PO Q 8 H), clopidogrel (18.75 mg PO Q 48 H), and maropitant (24 mg PO Q 24 H). In an attempt to prevent a recurrent episode of acute pancreatitis, an ultra low fat diet was recommended and any treats with high fat content were discouraged.

Follow-Up

Sidney was discharged after 7 days of hospitalization and was presented for a recheck 3 days after discharge. Sidney’s owners reported that she had a good appetite, and there were no signs of abdominal pain. No vomiting or diarrhea was identified.

Prognosis

The prognosis for dogs with acute pancreatitis varies and largely depends on disease severity. There is no universally accepted severity score for pancreatitis that allows prediction of prognosis available in veterinary medicine. In general, systemic complications can indicate severe pancreatitis and a poor prognosis.¹

A recent study² suggested that serum paraoxonase 1 activity, combined with triglyceride and C-reactive protein concentrations, can help evaluate disease severity, but further studies are warranted. In Sidney’s case, prognosis was poor to guarded when she was hospitalized, but upgraded to fair to good upon discharge. However, long-term follow-up was not achieved.

Acute Pancreatitis: Diagnostics

Even with the advanced diagnostic modalities currently available, accurate diagnosis of acute pancreatitis is still challenging. Practically, acute pancreatitis in dogs is usually diagnosed with a combination of history, clinical signs, abnormally high serum cPLI concentration (as measured by Spec cPL), and abdominal ultrasonographic images consistent with pancreatitis. Concurrently, other intra-abdominal diseases that could cause similar clinical signs are excluded by assessment of laboratory test results, survey abdominal radiographs, and abdominal ultrasonography.

Pancreatic Lipase Immunoreactivity

Measurement of serum cPLI concentration is considered highly sensitive and specific for pancreatitis. The SNAP test provides semiquantitative estimation of cPLI concentration. A negative result rules out pancreatitis with high likelihood, whereas a positive result is consistent with pancreatitis and may require follow-up with the Spec cPL test.^6,7

Serum lipase activity has traditionally been used to estimate pancreatic lipase in serum. None of the substrates available (including newer substrates, such as triolein or DGGR [1,2-o-dilauryl-rac-glycero3-glutaric acid 6-methyl resorufin ester]), however, are specific for the measurement of pancreatic lipase, and results of clinical studies using these assays are inconsistent.^6,8

Cytology & Histopathology

Pancreatitis can be confirmed by cytologic evaluation of a fine-needle aspirate of the pancreas.⁷ Histopathology of the pancreas has traditionally been considered the gold standard for diagnosis and classification of pancreatitis. However, a recent study⁹ suggests that a negative finding (ie, no inflammatory lesions in the biopsy) does not rule out pancreatitis because pancreatic inflammation can be highly localized.

Advanced Imaging

Advanced imaging modalities, including contrast-enhanced computed tomography (CECT) and contrast-enhanced multidetector helical computed tomography (CE-MDCT), have been evaluated and shown different utility for diagnosing pancreatitis in dogs. A study using CE-MDCT¹⁰ showed low sensitivity for diagnosing pancreatitis in dogs presented with acute abdominal signs even though CE-MDCT was suggested as a good screening test to differentiate between surgical and nonsurgical conditions. A more recent study¹¹ using CECT concluded that CECT under sedation can confirm a clinical suspicion of pancreatitis. However, these modalities have limited availability for general use.

Acute Pancreatitis: Treatment

Because most cases of acute pancreatitis in dogs are idiopathic, the mainstay of treatment is supportive care that includes risk factor control, fluid therapy, nutritional support, and pain control.

Fluid Therapy

Fluids are important to correct hypovolemia, dehydration, and electrolyte and acid–base imbalances as early as possible to prevent any systemic complications, which can be associated with a negative outcome. A study in human medicine¹² suggested a possible benefit of using lactated Ringer’s solution because the alkalinizing property of that solution prevented further trypsin activation within the acinar cells, but no data are available for dogs.

Nutritional Support

Several studies in both humans and dogs suggest that early enteral nutritional support is superior to parenteral feeding in patients with acute pancreatitis as long as it is tolerated.^13-16

• Enteral feeding can be achieved by voluntary intake in mild cases or by using different types of feeding tubes (nasoesophageal, nasogastric, esophagostomy, gastrostomy, or jejunostomy tubes) in more severe cases.¹⁷
• Gradually increasing the volume fed until the full energy requirement is reached is recommended regardless of the method of enteral alimentation.
• Generally, an easily digestible food is recommended. The benefit of using a low fat diet is anecdotal, but we feel strongly that an ultra low fat diet should be chosen for feeding. These diets should be fed both during hospitalization and also after discharge.
• If patients demonstrate severe nausea, vomiting, or abdominal pain before, during, or after feeding, enteral feeding should be discontinued and attempted later when these signs have been successfully controlled.

Pain Management

Every dog with acute pancreatitis should be considered as having abdominal pain even if it is not clinically apparent. A multimodal approach for pain management is advised for better pain control, lower dosages, and fewer adverse effects.

• Most commonly used analgesics include opioids, ketamine, or lidocaine for hospitalized patients.
• The use of a CRI of ketamine (5–20 mcg/kg/min) or lidocaine (25–50 mcg/kg/min) can decrease the amount of opioids required. Lidocaine may have some anti-inflammatory properties, based on evidence in human medicine.¹⁸
• Outpatients can receive tramadol (5 mg/kg PO Q 6–8 H), an opioid, gabapentin (5–15 mg/kg PO Q 12 H), and/or a fentanyl patch.

Antiemetic Agents

Antiemetic treatment should be started as early as possible even in dogs without overt nausea or vomiting to encourage patients to eat voluntarily.

• Maropitant (1 mg/kg SC Q 24 H for a maximum 5 days), a neurokinin1 receptor inhibitor, is recommended as a first choice antiemetic due to its high efficacy and visceral analgesic properties.
• Dolasetron (0.6 mg/kg IV or SC Q 12–24 H) or ondansetron (0.1–0.2 mg/kg slow IV Q 6–12 H), both 5-HT₃ antagonists, can also be used.
• Because maropitant and the 5-HT₃ antagonists act on different receptors, we commonly use both types of drugs concurrently in patients with severe pancreatitis.
• Metoclopramide (a dopamine inhibitor), which has been traditionally used, is not currently recommended due to its low efficacy as an antiemetic and its effect on splanchnic perfusion.¹⁹

Plasma Transfusion

The proposed advantage of using plasma in dogs with acute pancreatitis includes supplementation of alpha-2-macroglobulin (scavenger proteins for activated proteases in serum), coagulation factors, and anti-inflammatory factors.²⁰ Due to the high cost and lack of confirmed benefits in dogs, however, plasma transfusion is generally reserved for dogs suspected to have DIC.

Antibiotics

Bacterial complications are extremely rare in dogs with naturally occurring acute pancreatitis. Only dogs with overt bacterial infections or a strong suspicion for such an infection should be given broad spectrum antibiotics.

Amoxicillin/clavulanate acid (12.5–25 mg/kg PO Q 12 H) or ticarcillin (33–50 mg/kg IV or IM Q 4–6 H) has been recommended as first choice antibiotics, if needed, but this recommendation is based on expert opinion rather than critical research.²¹

Corticosteroid Therapy

No prospective studies demonstrate beneficial effects of corticosteroid therapy in dogs with acute pancreatitis. Reserve corticosteroids for patients who have critical illness-related corticosteroid insufficiency causing refractory hypotension, even with aggressive fluid therapy.

In Summary

Canine acute pancreatitis is a reversible disease when diagnosed promptly and managed appropriately. Avoiding known risk factors and careful monitoring after the first episode are important in prevention of progression to chronic pancreatitis or recurrent acute pancreatitis.

CBC = complete blood count; CECT = contrast-enhanced computed tomography; CE-MDCT = contrast-enhanced multidetector helical computed tomography; cPLI = pancreatic lipase immunoreactivity; CRI = constant rate infusion; DIC = disseminated intravascular coagulation; GI = gastrointestinal; RBC = red blood cell