Biological variation of thromboelastrography variables in 10 clinically healthy horses

OBJECTIVE

To assess the utility of population-based reference intervals (PRIs) for interpreting thromboelastography (TEG) variables in horses using biological variation data.

DESIGN

Prospective cohort biologic variation study conducted over a 5-week period.

SETTING

Veterinary teaching hospital and research facility.

ANIMALS

Ten clinically healthy horses randomly selected from a veterinary school research and teaching herd.

INTERVENTIONS

Horse health was determined using physical examination, CBC, and biochemical and coagulation profiles prior to the start of the study. Subsequently, once weekly blood sampling for TEG testing was performed for 5 weeks.

MEASUREMENTS AND MAIN RESULTS

The 4 TEG variables reaction time (R), clot formation time (K), angle, and maximum amplitude (MA) were measured, and coefficient of variation representing within- and between-horse biological variation (CVi and CVg , respectively) and coefficient of variation representing analytical variation (CVa ) were calculated using a nested ANOVA after removing outlier data. The CVi , CVg , and CVa for R were 26.8%, 5.2%, and 5.9%; for K were 31.0%, 0.0%, and 5.9%; for angle were 9.4%, 6.2%, and 21.7%; and for MA were 3.4%, 4.1%, and 4.4%, respectively. Index of individuality (IOI) was then calculated for each variable using the formula {( CVi² + CVa²/CVg²)}¹/². IOI for R was 5.3, for angle was 3.8, and for MA was 1.4; IOI was not assessed for K.

CONCLUSIONS

PRIs are appropriate for TEG variables, R, angle, and MA when interpreting results from individual horses based on calculated IOI values equal to or greater than 1.4. PRIs are likely appropriate when interpreting K, but IOI could not be calculated for this variable.

Efficacy of intravenous administration of combined acid suppressants in healthy dogs

Background

Short‐term intravenous co‐administration of famotidine and pantoprazole is used by some veterinarians to treat gastrointestinal bleeding in critically ill dogs. However, clinical studies have not evaluated the efficacy of combination acid suppressant treatment in dogs.

Hypothesis/Objectives

To compare the effect of intravenous co‐administration of famotidine and pantoprazole to monotherapy with pantoprazole on intragastric pH in dogs. We hypothesized that single agent pantoprazole would be more effective than combination with famotidine.

Animals

Twelve healthy adult colony dogs.

Methods

Randomized, 2‐way crossover design. All dogs received placebo (0.9% saline) for 24 hours followed by 1.0 mg/kg IV q12h pantoprazole or combination treatment with famotidine and pantoprazole for 3 consecutive days. Intragastric pH monitoring was used to continuously record intragastric pH for 96 hours beginning on day 0 of treatment. Mean percentage time (MPT) that intragastric pH was ≥3 and ≥4 were compared between groups using ANOVA with a posthoc Tukey‐Kramer test (α = 0.017).

Results

The MPT ± standard deviation intragastric pH was greater than ≥3 and 4 were 79 ± 17% and 68 ± 17% for pantoprazole and 74 ± 19% and 64 ± 23% for combination treatment, respectively. There were no significant differences in MPT intragastric pH was ≥3 and 4 between groups. Pantoprazole administered alone achieved pH goals established for humans with acid‐related disorders.

Conclusions and Clinical Importance

These results suggest that short‐term combination treatment with famotidine and pantoprazole is not superior to pantoprazole alone for increasing intragastric pH in dogs.

Evaluation of the effect of orally administered acid suppressants on intragastric pH in cats

Background

Acid suppressant drugs are a mainstay of treatment for cats with gastrointestinal erosion and ulceration. However, clinical studies have not been performed to compare the efficacy of commonly PO administered acid suppressants in cats.

Hypothesis/Objectives

To compare the effect of PO administered famotidine, fractionated omeprazole tablet (fOT), and omeprazole reformulated paste (ORP) on intragastric pH in cats. We hypothesized that both omeprazole formulations would be superior to famotidine and placebo.

Animals

Six healthy adult DSH colony cats.

Methods

Utilizing a randomized, 4‐way crossover design, cats received 0.88–1.26 mg/kg PO q12h fOT, ORP, famotidine, and placebo (lactose capsules). Intragastric pH monitoring was used to continuously record intragastric pH for 96 hours beginning on day 4 of treatment. Plasma omeprazole concentrations at steady state (day 7) were determined by high performance liquid chromatography (HPLC) with ultraviolet detection. Mean percentage time that intragastric pH was ≥3 and ≥4 were compared among groups using ANOVA with a posthoc Tukey‐Kramer test (α = 0.05).

Results

The mean percentage time ± SD that intragastric pH was ≥3 was 68.4 ± 35.0% for fOT, 73.9 ± 23.2% for ORP, 42.8 ± 18.6% for famotidine, and 16.0 ± 14.2% for placebo. Mean ± SD plasma omeprazole concentrations were similar in cats receiving fOT compared to those receiving ORP and in a range associated with acid suppression reported in other studies.

Conclusions and Clinical Importance

These results suggest that both omeprazole formulations provide superior acid suppression in cats compared to famotidine or placebo. Fractionated enteric‐coated OT is an effective acid suppressant despite disruption of the enteric coating.

Evaluation of a semiquantitative SNAP test for measurement of bile acids in dogs

Background. Serum bile acids (SBA) are used as a routine screening tool of liver function in dogs. Serum samples are usually shipped to a referral laboratory for quantitative analysis with an enzymatic chemistry analyzer. The canine SNAP Bile Acids Test (SNAP-BAT) provides an immediate, semi-quantitative measurement of bile acid concentrations in-house. With the SNAP-BAT, bile acids concentrations of 5–30 µmol/L are quantified, and results outside of that range are classified as <5 or >30 µmol/L. Agreement of the SNAP-BAT with the enzymatic method has not been extensively investigated.

Objectives. The purposes of this prospective clinical study were to assess the precision of the SNAP-BAT and determine agreement of SNAP-BAT with results from an in-house chemistry analyzer.

Methods. After verifying intra-assay precision of the SNAP-BAT, a prospective analysis was performed using blood samples collected from 56 dogs suspected to have liver disease. Each sample was analyzed with an enzymatic, in-house chemistry analyzer and the SNAP-BAT. Agreement between the two methods was statistically assessed using the κ index of agreement.

Results. Intra-assay variability was minimal. The κ index for agreement between the SNAP-BAT and routine chemistry analyzer was between 0.752 and 0.819, indicating substantial to near perfect agreement.

Conclusions. The SNAP-BAT is a highly accurate, semi-quantitative test that yields immediate results, and has very little intra-assay variability, particularly for results >30 µmol/L.

Magnetic resonance imaging of the canine abdomen: effect of pulse sequence on diagnostic quality

Motion artifact is an important limiting factor for abdominal magnetic resonance imaging (MRI) in veterinary patients. The purpose of this study was to determine the effects of pulse sequence on abdominal MRI diagnostic quality in dogs. Ten normal dogs were each scanned using 16 MRI pulse sequences. Sequences included breath-holding sequences, respiratory navigation sequences, and traditional spin-echo sequences. Four observers independently scored diagnostic quality for each sequence based on the appearance of specific organs, overall diagnostic quality, and degree of artifactual interference. Signal-to-noise ratio and contrast-to-noise ratio were also calculated for each sequence. The sequence with the highest overall mean diagnostic quality score was the dorsal T2 turbo spin echo (TSE) with fat saturation and breath-holding. The sequence with the lowest mean diagnostic quality score was the dorsal T2 fast spin echo. The sequence with the highest signal-to-noise ratio for all evaluated organs was the sagittal T1 spin echo. Signal-to-noise and contrast-to-noise ratios did not correlate with subjective assessment of overall diagnostic quality for the majority of the sequences evaluated (P < 0.05). The three sequences considered to have the highest diagnostic quality for the cranial abdomen were the dorsal T2 TSE with fat saturation and breath-hold, transverse T1 turbo fast low-angle shot gradient echo with breath-hold, and dorsal T2 half-Fourier acquisition single shot TSE with respiratory navigation. These sequences had short acquisition times, yielded studies of similar diagnostic quality, provided complementary information, and are therefore recommended for routine canine abdominal MRI protocols.

Diagnostic accuracy of tissue impedance measurement interpretation for correct Veress needle placement in feline cadavers

OBJECTIVE

To determine the diagnostic accuracy of tissue impedance measurement interpretation (TIMI) for determining correct versus incorrect Veress needle placement in feline cadavers.

STUDY DESIGN

Prospective, randomized, blinded trial.

STUDY POPULATION

Cat cadavers (n = 24).

METHODS

Two laparoscopists (1 experienced, 1 novice), blinded to TIMI, placed reusable Veress needles in study subjects in a randomized order. A third individual interpreted impedance measurements as consistent with correct versus incorrect placement. Veress needle tip locations were marked by injecting contrasting colors of India ink. Tissue dissection was performed to localize ink. Sensitivity, specificity, accuracy, precision, and kappa statistics for TIMI for placements by the experienced and novice laparoscopist were determined. P < .05 was considered significant.

RESULTS

TIMI identified 36/38 correct and 2/10 incorrect placements. TIMI identified 2/2 bowel perforations but was unable to identify 8 inappropriate placements in the retroperitoneal fat pad. Impedance measurement interpretation had 94.7% sensitivity, 20% specificity, 79.2% accuracy, and 81% precision overall. Agreement between TIMI and Veress needle location was absent (kappa = -0.15, P = .01) for placements by the experienced laparoscopist and substantial (kappa = 0.78, P < .01) for the novice laparoscopist.

CONCLUSIONS

Failure of TIMI to identify placement in the retroperitoneal fat pad resulted in poor accuracy. Small cat size limited the number of appropriate placement sites, perhaps resulting in excessively dorsal placements. Use of TIMI may increase detection of clinically significant inappropriate Veress needle placements, like bowel perforations, and decrease installment phase complications. Further evaluation of Veress needle placement with and without TIMI is warranted.