Beth M. Johnson DVM, DACVIM, College of Veterinary Medicine

Comparison of a human portable blood glucose monitor, a veterinary portable blood glucose monitor and an automated chemistry analyzer for measuring canine blood glucose concentration

Beth M. Johnson et al. — Fri, 26 Aug 2011 11:23:59 PDT

OBJECTIVE: To compare blood glucose concentrations measured with 2 portable blood glucose meters (PBGMs) validated for use in dogs (PBGM-D) and humans (PBGM-H) and an automated chemistry analyzer. DESIGN: Validation study. SAMPLE POPULATION: 92 samples of fresh whole blood and plasma from 83 dogs with various diseases. PROCEDURES: Each PBGM was used to measure whole blood glucose concentration, and the automated analyzer was used to measure plasma glucose concentration. Passing-Bablok linear regression and Bland-Altman plots were used to determine correlations and bias between the PBGMs and the automated analyzer. Calculated acceptability limits based on combined inherent instrument imprecision were used with Bland-Altman plots to determine agreement. Clinical relevance was assessed via error grid analysis. RESULTS: Although correlation between results of both PBGMs and the standard analyzer was > 0.90, disagreement was greater than could be explained by instrument imprecision alone. Mean difference between PBGM-H and chemistry-analyzer values was -15.8 mg/dL. Mean difference between PBGM-D and chemistry-analyzer values was 2.4 mg/dL. Linear regression analysis revealed proportional bias of PBGM-H (greater disagreement at higher glucose concentrations); no proportional bias was detected for PBGM-D. No constant bias was detected for either PBGM. Error grid analysis revealed all measurements from both PBGMs were within zones without an anticipated effect on clinical outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Neither PBGM had exact agreement with the automated analyzer; however, the disagreement detected did not have serious clinical consequences. Our findings stressed the importance of using the same device for monitoring trends in dogs and using instrument-specific reference ranges.

Canine Megaesophagus

Beth M. Johnson et al. — Thu, 11 Aug 2011 07:39:42 PDT

Adrenal response to adrenocorticotropic hormone in dogs before and after surgical attenuation of a single congenital portosystemic shunt

Amy Holford et al. — Thu, 11 Aug 2011 06:20:35 PDT

Background: Dogs with single congenital portosystemic shunts (CPSS) often develop postoperative hypoglycemia and prolonged anesthetic recovery. These abnormalities could be attributable to inadequate adrenal response. However, adequacy of adrenal response after CPSS surgery is unexplored.

Hypothesis: Dogs with CPSS have inadequate postoperative adrenal response.

Animals: Eight nonoperated, 8 ovariohysterectomy (OHE), and 16 CPSS dogs.

Methods: Consecutive day ACTH stimulation tests were performed on nonoperated healthy dogs, healthy dogs before and after OHE, and CPSS dogs before and after surgery. Adequate response was defined as >50% or >30 ng/mL increase in cortisol after ACTH administration. Blood glucose (BG) was monitored before and after surgery. Prolonged anesthetic recovery and refractory hypoglycemia episodes were recorded.

Results: Results of consecutive day ACTH stimulation tests did not vary in normal dogs. Results of preoperative ACTH stimulation tests of CPSS and OHE dogs were not significantly different. Dogs with CPSS had higher postoperative baseline cortisol concentrations (median, 329 ng/mL) than OHE dogs (median, 153 ng/mL). Postoperative cortisol increase after ACTH in CPSS was ≤50% in 10/16 and ≤30 ng/mL in 6/16. After surgery, BG was ≤60 mg/dL in 7/16 CPSS dogs. Cortisol concentrations were not correlated with BG. Two CPSS dogs had refractory hypoglycemia and 4 had delayed recovery; all improved with dexamethasone administration (0.1–0.2 mg/kg/IV).

Conclusions and Clinical Importance: Contrary to previous reports, baseline cortisol concentrations in CPSS and healthy dogs are similar. Many CPSS dogs have postoperative hypercortisolemia. Response to ACTH does not correlate with postoperative hypoglycemia or prolonged anesthetic recovery.