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Keywords:

  • acute phase protein;
  • CRP;
  • dogs;
  • inflammation;
  • pancreas

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Footnotes
  8. References

Objective: To determine if C-reactive protein (CRP) concentration is elevated in spontaneously occurring canine acute pancreatitis (AP), and to measure changes in CRP during the course of hospitalization.

Design: Prospective study.

Setting: Tufts University School of Veterinary Medicine Foster Hospital for Small Animals.

Animals: Sixteen client-owned dogs with AP and 16 healthy controls.

Interventions: Blood samples were obtained from the AP group on the day of diagnosis (Day 1), and on Days 3 and 5, unless the dog died or was discharged from the hospital. Blood was obtained from the control dogs once.

Measurements and main results: Serum CRP was measured using a commercial immunoassay for each dog with AP and for healthy controls. Day 1 CRP concentrations were significantly higher in the AP group (56.1±12.7 μg/mL) compared with controls (2.8±1.3 μg/mL; P<0.001). For the 7 dogs that had samples collected on all 3 days, the mean CRP concentrations decreased significantly (P=0.043) over the 5 days of measurement. Of the 16 dogs with AP, 14 were discharged from the hospital and 2 were euthanized.

Conclusions: Serum CRP concentrations were elevated in this group of 16 dogs with spontaneously occurring AP. In the 7 dogs that had measurements on all 3 days, the mean CRP concentration decreased from the day of diagnosis to the measurement made 5 days later.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Footnotes
  8. References

Acute pancreatitis (AP) is a common disease in dogs. Although most cases are mild and self-limiting, some cases develop systemic complications that can result in death.1–3 The reported mortality rates of severe AP in dogs range from 27 to 42%.1,3 In human patients, the degree of pancreatic necrosis and the presence of bacterial infection are 2 important factors in determining development of multi-organ failure and subsequent mortality.4,5 A recent veterinary report documented acute pancreatic necrosis in 67/70 (96%) of dogs with fatal AP.2

There is much interest in early identification of human patients at risk for developing severe AP, so a considerable research effort has been made to identify a serum marker of pancreatic necrosis.6–12 The acute phase reactant, C-reactive protein (CRP), is produced by the liver in response to inflammation, infection, or tissue destruction. CRP synthesis is induced by tumor necrosis factor (TNF), interleukin (IL)-1, and IL-6, which are hallmarks of systemic inflammation.8,11,13 The low cost and ease of performing CRP assays have led to widespread use in humans for a variety of conditions.14,15 CRP is currently the gold standard serum marker for predicting the severity of disease in human AP.15 The sensitivity and specificity of CRP in predicting pancreatic necrosis are reported to be greater than 85%.8,10,12 Extensive evaluation of CRP has resulted in a cutoff value of 150 mg/L as the standard for distinguishing mild from severe AP in human patients.16

CRP is elevated in dogs with infection, trauma, inflammation, and with experimentally induced AP.17–27 While there are no published studies evaluating CRP concentrations in dogs with spontaneously occurring AP, a recently published abstract supports the hypothesis that CRP concentrations may have prognostic value as it was found to be significantly higher in dogs with severe AP (with pancreatic necrosis) compared with dogs with mild (interstitial) AP.a The goals of this study were (1) to determine if CRP concentration is elevated in spontaneously occurring canine AP and (2) to measure changes in CRP during hospitalization.

Materials and Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Footnotes
  8. References

Cases

Client-owned dogs presented to the Tufts University School of Veterinary Medicine Foster Hospital for Small Animals and diagnosed with AP were included in the study. For a diagnosis of AP to be made, a dog had to have all of the following 4 criteria: (1) a history of acute onset of signs compatible with AP such as anorexia, vomiting, weakness, or diarrhea; (2) an initial physical examination that included dehydration, icterus, fever, or abdominal pain; (3) abdominal ultrasound findings consistent with AP (enlarged, hypoechoic pancreas with hyperechoic, peripancreatic fat); and (4) a clinical diagnosis of AP by the attending hospital clinician. Blood samples were collected in a red top tubeb for measurement of serum CRP concentrations on the day of diagnosis (Day 1) and Days 3 and 5 unless the animal died or was discharged from the hospital prior to subsequent sample collection. Dogs that had a history of recent trauma, surgery, or surgical treatment of AP were excluded. The study was approved by the Tufts University School of Veterinary Medicine Institutional Animal Care and Use Committee. All owners signed an informed consent form before enrolling their dogs in the study.

Controls

Normal, healthy dogs served as controls for the dogs with AP. Control dogs were included in the study if they had a normal physical examination, and if no major abnormalities were noted on a complete blood count (CBC), biochemistry profile, or urinalysis. Dogs with a history of an acute or chronic medical condition, surgery, or physical trauma within the previous 60 days were not eligible for the study. Blood was collected for serum CRP analysis once.

CRP assay

Blood was centrifuged 10–15 minutes after collection at 1500 g at room temperature for 10 minutes, and serum was stored at −70°C until analysis. All serum samples were analyzed in a single run in duplicate with a commercially available enzyme-linked immunosorbent assay for canine CRP levels according to the manufacturer's instructions.c,28 Samples were stored for a maximum of 7 months.

Statistical analysis

Data were examined graphically. Data that were not normally distributed were transformed prior to analysis. Categorical variables were compared between the AP and control groups using χ2-analysis. Baseline concentrations of CRP were compared between the AP and control groups using an independent t-test. Changes in CRP concentrations during hospitalization in the AP group were compared using analysis of variance with repeated measures. A P-value of <0.05 was considered significant. All analyses were performed using commercial statistical software.d

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Footnotes
  8. References

Sixteen dogs with AP and 16 controls were enrolled in the study between July 2002 and March 2003. The AP group included 10 spayed females, 5 castrated males, and 1 intact female, while the control group included 10 spayed females and 6 castrated males. The median age was not different between the AP group (9 years; range 6 months to 17 years) and the control group (7 years; range 2–12 years; P=0.126). There was also no significant difference in weight between the 2 groups (mean weight for the AP group was 22.8±12.3 kg versus 23.7±7.4 kg for the control group; P=0.814). Breeds in the AP group included Labrador retriever (n=2), Samoyed (n=2), Cocker spaniel (n=2), and 1 each of the following: German shepherd, Vizla, Springer spaniel, Lhasa Apso, Jack Russell terrier, Rottweiler, Australian shepherd, Kerry Blue terrier, Shetland sheepdog, and Bernese Mountain dog. The control group included mixed breed dogs (n=7), Labrador retriever (n=5), Beagle (n=2), Briard (n=1), and Jindo (n=1). Nine of 16 dogs with AP also had a number of concurrent diseases: diabetes mellitus (n=3; 2 with ketoacidosis), glomerulonephritis (n=2), and one each of epilepsy, inflammatory bowel disease (IBD), systemic lupus erythematosus, and cystic calculi with urinary tract infection. Treatments in the dogs with AP were varied but the most common treatments included intravenous fluids (n=16), antibiotics (n=16), H2 antagonist (n=15), analgesics (n=10), and parenteral nutrition (n=5).

Samples were not obtained from all 16 dogs on all 3 days of measurements. Seven dogs had measurements on all 3 days, while some dogs had measurements only on Days 1 and 3 of the study (n=7) or only on Day 1 of the study (n=2). Day 1 mean CRP concentration was significantly higher in the AP group (n=16; 56.1±12.7 μg/mL) as compared with controls (2.8±1.3 μg/mL; P<0.001). CRP concentrations on Days 3 (n=14; P<0.001) and 5 (n=7; P<0.001) were also significantly higher in AP versus controls. For the 7 dogs in the AP group that had samples collected for all 3 time points, the mean CRP concentration decreased significantly (P=0.043) over the 5 days of measurement (Figure 1). However, CRP concentrations remained significantly higher than controls on Day 5. The mean hospitalization time for dogs in the AP group was 7.5±3.2 days. Fourteen of the 16 dogs with AP were discharged from the hospital, and 2 of 16 were euthanized due to a guarded prognosis and financial constraints. The 2 dogs that were euthanized had only one CRP measurement each.

image

Figure 1.  Mean C-reactive protein concentrations for healthy controls (shaded bar, Day 1 only; n=16) and dogs with acute pancreatitis (open bars) on Days 1 (n=16), 3 (n=14), and 5 (n=7). *C-reactive protein concentrations (μg/mL) were significantly different between controls versus dogs with acute pancreatitis on Days 1, 3, and 5. §C-reactive protein concentrations (μg/mL) decreased significantly over the 5 days of measurement for the 7 dogs with acute pancreatitis that had all 3 samples collected.

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Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Footnotes
  8. References

In the present study, CRP concentrations were found to be significantly higher in dogs with spontaneously occurring AP compared with controls. This finding was expected based on previous studies evaluating CRP concentrations in dogs with other inflammatory and infectious diseases, including experimentally induced AP.16–26 In humans, CRP concentrations have also been shown to be elevated in diseases associated with an acute phase response such as AP.5–15

The mean CRP concentration decreased significantly over time in the 7 dogs that had measurements at all 3 time points, but remained significantly higher than in the control group even on Day 5 after diagnosis of AP. Individual CRP concentrations decreased in 6 of these 7 dogs and increased in 1/7 dogs. Previous studies in dogs with surgical trauma and other inflammatory diseases suggest that CRP concentrations fall rapidly (within 3–14 days), provided there is no ongoing stimulus.17,18,22 All 7 of these dogs in the current study demonstrated clinical improvement and were discharged from the hospital. This finding suggests that CRP concentrations may be useful in monitoring clinical progression and response to therapy in dogs with AP, similar to what has been shown in humans.29 A recent veterinary report correlated a clinical scoring system for dogs with IBD to objective laboratory and histologic indices of intestinal inflammation.23 This IBD study documented significantly decreased CRP concentrations after successful medical therapy as compared with pretreatment values, suggesting that CRP is a useful laboratory measure of the effect of therapy for dogs with IBD.23

One limitation of this study is the criteria used for defining pancreatitis. This is a controversial issue and there is no single accepted set of criteria that has been used for identifying dogs with this disease. Another complicating issue is that some of the dogs in the study, similar to many dogs with AP, had concurrent diseases. The degree of influence of these other diseases on CRP concentrations in the current study is not clear. Other limitations include the variability in treatment for dogs with AP and the fact that only 7 dogs had measurements on all 3 days. It cannot be concluded from the current study as to whether the decrease in CRP during hospitalization was directly due to improvement of the AP, to specific treatments, or to the effects of concurrent diseases. Therefore, further studies with a larger number of cases more varied in severity are warranted to determine the utility of CRP as a predictor of severity in canine AP.

Footnotes

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Footnotes
  8. References

aSpillman T, Korrell J, Wittker A, et al. Serum canine pancreatic elastase and canine C-reactive protein for the diagnosis and prognosis of acute pancreatitis in dogs. J Vet Intern Med 2002; 16(5):635.

bVacutainer tubes, Becton, Dickinson and Company, Franklin Lakes, NJ.

cTri-Delta Phase™ Canine CRP assay, Tridelta Diagnostics Inc., Morris Plains, NJ.

dSystat 9.0, SPSS, Chicago, IL.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Footnotes
  8. References
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