Neoplastic melanocytic pleural effusion in a Portuguese water dog.

A 9-year-old castrated male Portuguese water dog was presented following incomplete excision of a malignant melanoma at the left lip commissure by the referring veterinarian. Physical examination was otherwise unremarkable. The patient was staged using thoracic radiographs, abdominal ultrasound, and fine-needle aspirates of the mandibular lymph nodes and spleen. Given the absence of any definitive evidence of metastasis, the malignant melanoma was surgically completely removed. The dog then received four melanoma vaccine doses as an adjuvant therapy and remained clinically healthy for more than 3 months after the last immunization. However, 232 days after the initial discovery of the lip mass, the dog was euthanized due to deterioration and a poor prognosis based on the presence of lung metastases and neoplastic melanocytic pleural effusion. The latter has been rarely reported in dogs, despite the high prevalence of oral malignant melanomas and the tendency of these tumors to metastasize to the lungs.

Association of fecal calprotectin concentrations with disease severity, response to treatment, and other biomarkers in dogs with chronic inflammatory enteropathies.

BACKGROUND: Calprotectin is a marker of inflammation, but its clinical utility in dogs with chronic inflammatory enteropathies (CIE) is unknown. OBJECTIVE: Evaluation of fecal calprotectin in dogs with biopsy-confirmed CIE. ANIMALS: 127 dogs. METHODS: Prospective case-control study. Dogs were assigned a canine chronic enteropathy clinical activity index (CCECAI) score, and histologic lesions severity was assessed. Fecal calprotectin, fecal S100A12, and serum C-reactive protein (CRP) were measured. Food- or antibiotic-responsive cases (FRE/ARE, n = 13) were distinguished from steroid-/immunosuppressant-responsive or -refractory cases (SRE/IRE, n = 20). Clinical response to treatment in SRE/IRE dogs was classified as complete remission (CR), partial response (PR), or no response (NR). RESULTS: Fecal calprotectin correlated with CCECAI (ρ = 0.27, P = .0065) and fecal S100A12 (ρ = 0.90, P < .0001), some inflammatory criteria, and cumulative inflammation scores, but not serum CRP (ρ = 0.16, P = .12). Dogs with SRE/IRE had higher fecal calprotectin concentrations (median: 2.0 µg/g) than FRE/ARE dogs (median: 1.4 µg/g), and within the SRE/IRE group, dogs with PR/NR had higher fecal calprotectin (median: 37.0 µg/g) than dogs with CR (median: 1.6 µg/g). However, both differences did not reach statistical significance (both P = .10). A fecal calprotectin ≥15.2 µg/g separated both groups with 80% sensitivity (95% confidence interval [95%CI]: 28%-100%) and 75% specificity (95%CI: 43%-95%). CONCLUSIONS AND CLINICAL IMPORTANCE: Fecal calprotectin could be a useful surrogate marker of disease severity in dogs with CIE, but larger longitudinal studies are needed to evaluate its utility in predicting the response to treatment.

Effect of gastric acid-suppressive therapy and biological variation of serum gastrin concentrations in dogs with chronic enteropathies.

BACKGROUND: Serum gastrin concentration can help diagnose gastrinomas in dogs if >3-10× the upper reference limit (URL), but antisecretory therapy and other conditions can also cause hypergastrinemia. Effects of antisecretory therapy (famotidine or ranitidine, omeprazole) on serum gastrin concentration in dogs with chronic enteropathy (CE) and its biological variation (BV) are unknown. Aim of the study was to evaluate serum gastrin in acid-suppressant-treated or -naïve CE dogs; test the association between serum gastrin and histopathologic findings in acid-suppressant-naïve CE dogs; and evaluate the BV of serum gastrin in dogs not receiving any gastric acid suppressive therapy. Samples from 231 dogs were used and serum gastrin was measured by chemiluminescence assay. Gastric and duodenal histologic lesions were evaluated and graded. BV of serum gastrin was evaluated in serial samples. RESULTS: Serum gastrin concentrations were significantly higher in acid-suppressant-treated than acid-suppressant-naïve dogs (P = 0.0245), with significantly higher concentrations in proton pump inhibitor (PPI)- than H2-antihistamine-treated patients (P = 0.0053). More PPI- than H2-antihistamine-treated dogs had gastrin concentrations above URL (P = 0.0205), but not >3× nor >10× the URL. Serum gastrin concentrations correlated with the severity of gastric antral epithelial injury (P = 0.0069) but not with any other lesions or the presence/numbers of spiral bacteria in gastric biopsies. Intra- and inter-individual BV were 43.4 and 21.6%, respectively, in acid-suppressant-naïve dogs, with a reciprocal individuality index of 0.49 and a critical difference of ≥29.5 ng/L. CONCLUSIONS: Antisecretory (particularly PPI) treatment leads to hypergastrinemia in CE dogs, but the concentrations seen in this study are unlikely to compromise a diagnosis of gastrinoma. Use of a population-based URL for canine serum gastrin and a URL of ≤27.8 ng/L are appropriate.

Development and analytic validation of an electron ionization gas chromatography/mass spectrometry (EI-GC/MS) method for the measurement of 3-bromotyrosine in canine serum.

BACKGROUND: The activation of eosinophils causes the release of eosinophil peroxidase and subsequent production of 3-bromotyrosine (3-BrY), a stable byproduct. In people, 3-BrY is used as a biomarker for eosinophil activation. The method for measuring 3-BrY concentrations in biologic samples from dogs has not previously been described. OBJECTIVES: The objective of this study was to develop and analytically validate an electron ionization gas chromatography/mass spectrometry (EI-GC/MS) method for the measurement of 3-BrY in canine serum samples. METHODS: Pooled canine serum samples were utilized to validate the assay. Serum samples from healthy control dogs (n = 41) were used to evaluate 3-BrY concentrations and establish a reference interval. RESULTS: The analytic validation revealed that the limit of blank and limit of detection were 0.33 and 0.63 µmol/L, respectively. The coefficients of variation for precision and reproducibility for 3-BrY were < 13.9% and < 11.0%, respectively. The means ± SD of observed-to-expected ratios for linearity and accuracy were 109.6 ± 17.2% and 98.7 ± 11.3%, respectively. The reference interval was determined as ≤ 1.12 µmol/L (median [range]: ≤ 0.63 µmol/L [≤ 0.63-1.13]). CONCLUSIONS: The EI-GC/MS assay described here for the measurement of 3-BrY in canine serum samples was precise, reproducible, linear, and accurate. Further studies are underway to determine the diagnostic utilities in canine patients with eosinophilic diseases.

Analytic validation of a gas chromatography-mass spectrometry method for quantification of six amino acids in canine serum samples.

OBJECTIVE: To analytically validate a gas concentration of chromatography-mass spectrometry (GC-MS) method for measurement of 6 amino acids in canine serum samples and to assess the stability of each amino acid after sample storage. SAMPLES: Surplus serum from 80 canine samples submitted to the Gastrointestinal Laboratory at Texas A&M University and serum samples from 12 healthy dogs. PROCEDURES: GC-MS was validated to determine precision, reproducibility, limit of detection, and percentage recovery of known added concentrations of 6 amino acids in surplus serum samples. Amino acid concentrations in serum samples from healthy dogs were measured before (baseline) and after storage in various conditions. RESULTS: Intra- and interassay coefficients of variation (10 replicates involving 12 pooled serum samples) were 13.4% and 16.6% for glycine, 9.3% and 12.4% for glutamic acid, 5.1% and 6.3% for methionine, 14.0% and 15.1% for tryptophan, 6.2% and 11.0% for tyrosine, and 7.4% and 12.4% for lysine, respectively. Observed-to-expected concentration ratios in dilutional parallelism tests (6 replicates involving 6 pooled serum samples) were 79.5% to 111.5% for glycine, 80.9% to 123.0% for glutamic acid, 77.8% to 111.0% for methionine, 85.2% to 98.0% for tryptophan, 79.4% to 115.0% for tyrosine, and 79.4% to 110.0% for lysine. No amino acid concentration changed significantly from baseline after serum sample storage at -80°C for ≤ 7 days. CONCLUSIONS AND CLINICAL RELEVANCE: GC-MS measurement of concentration of 6 amino acids in canine serum samples yielded precise, accurate, and reproducible results. Sample storage at -80°C for 1 week had no effect on GC-MS results.

Laboratory tests for the diagnosis and management of chronic canine and feline enteropathies.

Chronic enteropathies are commonly encountered in both cats and dogs. Although definitive diagnosis often requires collection of gastrointestinal biopsies for histopathologic evaluation, less invasive laboratory tests can be highly informative and should be performed prior to biopsy collection. Tests for determination of infectious causes comprise those for helminthic, protozoal, bacterial, or fungal organisms. Intestinal function and disease may be assessed by measuring serum concentrations of cobalamin, folate, and C-reactive protein, and fecal concentrations of α(1)-proteinase inhibitor. Ongoing research has led to development of tests for serum perinuclear antineutrophilic cytoplasmic antibodies, and fecal inflammatory markers, including S100-proteins and N-methylhistamine.

Development and analytic validation of a gas chromatography-mass spectrometry method for the measurement of sugar probes in canine serum.

OBJECTIVE: To develop and analytically validate a gas chromatography-mass spectrometry (GC-MS) method for the quantification of lactulose, rhamnose, xylose, 3-O-methylglucose, and sucrose in canine serum. SAMPLE POPULATION: Pooled serum samples from 200 dogs. Procedures-Serum samples spiked with various sugars were analyzed by use of GC-MS. The method was analytically validated by determination of dilutional parallelism, spiking recovery, intra-assay variability, and interassay variability. RESULTS: Standard curves ranging from 0.5 to 500 mg/L for each sugar revealed a mean r(2) of 0.997. The lower detection limit was 0.03 mg/L for lactulose, rhamnose, xylose, and methylglucose and 0.12 mg/L for sucrose. The observed-to-expected ratios for dilutional parallelism had a mean +/- SD of 105.6 +/- 25.4% at dilutions of 1:2, 1:4, and 1:8. Analytic recoveries for the GC-MS assays of sugars ranged from 92.1% to 124.7% (mean +/- SD, 106.2 +/- 13.0%). Intra-assay coefficients of variation ranged from 6.8% to 12.9% for lactulose, 7.1% to 12.8% for rhamnose, 7.2% to 11.2% for xylose, 8.9% to 11.5% for methylglucose, and 8.9% to 12.0% for sucrose. Interassay coefficients of variation ranged from 7.0% to 11.5% for lactulose, 6.4% to 9.4% for rhamnose, 6.8% to 13.2% for xylose, 7.0% to 15.9% for methylglucose, and 5.5% to 9.4% for sucrose. CONCLUSIONS AND CLINICAL RELEVANCE: The GC-MS method described here was accurate, precise, and reproducible for the simultaneous measurement of sugar probes in canine serum.

Evaluation of gastrointestinal permeability and mucosal absorptive capacity in dogs with chronic enteropathy.

OBJECTIVE: To assess intestinal mucosal function by measuring permeability and absorptive capacity in dogs with chronic enteropathy (CE) before and after treatment and to determine whether those variables were correlated with clinical disease activity or histologic scoring of intestinal biopsy specimens. ANIMALS: 29 dogs with CE. PROCEDURE: Dogs were designated as having dietresponsive CE or CE requiring glucorticoid treatment. Severity of clinical signs was assessed by calculating the canine inflammatory bowel disease activity index (CIBDAI). Histologic severity of intestinal infiltration was assessed before and after 4 weeks of treatment in the diet-responsive group and before and after 10 weeks of treatment in the glucocorticoid group. Gastrointestinal permeability and mucosal absorptive capacity were assessed by use of intragastric administration of a solution containing lactulose, rhamnose, xylose, 3-O-methylglucose, and sucrose. Urine was collected 6 hours after administration of the sugar solution to determine urinary lactulose-to-rhamnose (L:R), xylose-to-methylglucose (X:M), and sucrose-to-methylglucose (S:M) ratios. RESULTS: Median CIBDAI scores decreased significantly in both groups of dogs after treatment. However, the median histologic grade of intestinal biopsy specimens did not change with treatment in either group. There were no significant differences in L:R, X:M, or S:M ratios after treatment in either group and no significant correlations between L:R, X:M, or S:M ratios and CIBDAI or histologic scores. CONCLUSIONS AND CLINICAL RELEVANCE: Results of tests for intestinal permeability and mucosal absorptive capacity were not useful indicators of clinical disease activity as assessed by the CIBDAI or the sever ity of infiltration as indicated by histologic evaluation.