Co-impairment of autonomic and glucagon responses to insulin-induced hypoglycemia in dogs with naturally occurring insulin-dependent diabetes mellitus.

This study aimed to investigate the contributions of two factors potentially impairing glucagon response to insulin-induced hypoglycemia (IIH) in insulin-deficient diabetes: 1) loss of paracrine disinhibition by intra-islet insulin and 2) defects in the activation of the autonomic inputs to the islet. Plasma glucagon responses during hyperinsulinemic-hypoglycemic clamps ([Formula: see text]40 mg/dL) were assessed in dogs with spontaneous diabetes (n = 13) and in healthy nondiabetic dogs (n = 6). Plasma C-peptide responses to intravenous glucagon were measured to assess endogenous insulin secretion. Plasma pancreatic polypeptide, epinephrine, and norepinephrine were measured as indices of parasympathetic and sympathoadrenal autonomic responses to IIH. In 8 of the 13 diabetic dogs, glucagon did not increase during IIH (diabetic nonresponder [DMN]; ∆ = -6 ± 12 pg/mL). In five other diabetic dogs (diabetic responder [DMR]), glucagon responses (∆ = +26 ± 12) were within the range of nondiabetic control dogs (∆ = +27 ± 16 pg/mL). C-peptide responses to intravenous glucagon were absent in diabetic dogs. Activation of all three autonomic responses were impaired in DMN dogs but remained intact in DMR dogs. Each of the three autonomic responses to IIH was positively correlated with glucagon responses across the three groups. The study conclusions are as follows: 1) Impairment of glucagon responses in DMN dogs is not due to generalized impairment of α-cell function. 2) Loss of tonic inhibition of glucagon secretion by insulin is not sufficient to produce loss of the glucagon response; impairment of autonomic activation is also required. 3) In dogs with major ß-cell function loss, activation of the autonomic inputs is sufficient to mediate an intact glucagon response to IIH.NEW & NOTEWORTHY In dogs with naturally occurring, insulin-dependent (C-peptide negative) diabetes mellitus, impairment of glucagon responses is not due to generalized impairment of α-cell function. Loss of tonic inhibition of glucagon secretion by insulin is not sufficient, by itself, to produce loss of the glucagon response. Rather, impaired activation of the parasympathetic and sympathoadrenal autonomic inputs to the pancreas is also required. Activation of the autonomic inputs to the pancreas is sufficient to mediate an intact glucagon response to insulin-induced hypoglycemia in dogs with naturally occurring diabetes mellitus. These results have important implications that include leading to a greater understanding and insight into the pathophysiology, prevention, and treatment of hypoglycemia during insulin treatment of diabetes in companion dogs and in human patients.

Curricular Revision and Reform: The Process, What Was Important, and Lessons Learned.

Beginning in 2005, the Doctor of Veterinary Medicine program at the University of California underwent major curricular review and reform. To provide information for others that follow, we have documented our process and commented on factors that were critical to success, as well as factors we found surprising, difficult, or problematic. The review and reform were initiated by the Executive Committee, who led the process and commissioned the committees. The planning stage took 6 years and involved four faculty committees, while the implementation stage took 5 years and was led by the Curriculum Committee. We are now in year 2 of the institutionalizing stage and no longer refer to our reform as the "new curriculum." The change was driven by a desire to improve the curriculum and the learning environment of the students by aligning the delivery of information with current teaching methodologies and implementing adult learning strategies. We moved from a department- and discipline-based curriculum to a school-wide integrated block curriculum that emphasized student-centered, inquiry-based learning. A limit was placed on in-class time to allow students to apply classroom knowledge by solving problems and cases. We found the journey long and arduous, requiring tremendous commitment and effort. In the change process, we learned the importance of adequate planning, leadership, communication, and a reward structure for those doing the "heavy lifting." Specific to our curricular design, we learned the importance of the block leader role, of setting clear expectations for students, and of partnering with students on the journey.

Laparoscopic Adrenalectomy for Removal of Unilateral Noninvasive Pheochromocytomas in 10 Dogs.

OBJECTIVE: To report the surgical technique and outcome of dogs undergoing laparoscopic adrenalectomy for removal of unilateral noninvasive pheochromocytoma. STUDY DESIGN: Retrospective case series. ANIMALS: Dogs with unilateral noninvasive adrenal tumors (n=10). METHODS: Medical records of dogs that underwent laparoscopic adrenalectomy for histologically confirmed pheochromocytoma were reviewed. Dogs were positioned in lateral recumbency with the table tilted up to create a semi-sternal position. Three or 4 ports were used and dissection of the mass proceeded using a combination of laparoscopic instrumentation, bipolar vessel-sealing devices, and in some cases monopolar electrosurgical probes. Conversion rate, complications, surgical time, hospitalization time, and long-term follow-up were recorded. RESULTS: The procedure was completed without the need for conversion in 9 of 10 dogs. In 1 dog, hemorrhage obscured the visual field and conversion to an open approach was elected. In 5 cases, a 3-port approach was used, and in 5 cases, a 4th port was placed. Median surgical time was 105 minutes (range, 65-250). Intraoperative complications included 1 splenic laceration. Postoperatively, 1 dog developed gastric dilatation-volvulus. All dogs were discharged from the hospital. Median follow-up time was 16.0 months (range, 6.9-38.0). CONCLUSION: With careful case selection, laparoscopic adrenalectomy for resection of pheochromocytoma was feasible and could be performed efficiently by experienced laparoscopic surgeons.

Evaluation of total dietary fiber concentration and composition of commercial diets used for management of diabetes mellitus, obesity, and dietary fat-responsive disease in dogs.

OBJECTIVE: To determine total dietary fiber (TDF) concentration and composition of commercial diets used for management of obesity, diabetes mellitus, and dietary fat-responsive disease in dogs. DESIGN: Cross-sectional study. SAMPLE: Dry (n = 11) and canned (8) canine therapeutic diets. PROCEDURES: Insoluble and soluble dietary fiber (IDF and SDF), high-molecular-weight SDF (HMWSDF), and low-molecular-weight SDF (LMWSDF) concentrations were determined. Variables were compared among diets categorized by product guide indication, formulation (dry vs canned), and regulatory criteria for light and low-fat diets. RESULTS: SDF (HMWSDF and LMWSDF) comprised a median of 30.4% (range, 9.4% to 53.7%) of TDF; LMWSDF contributed a median of 11.5% (range, 2.7% to 33.8%) of TDF. Diets for diabetes management had higher concentrations of IDF and TDF with lower proportions of SDF and LMWSDF contributing to TDF, compared with diets for treatment of fat-responsive disease. Fiber concentrations varied within diet categories and between canned and dry versions of the same diet (same name and manufacturer) for all pairs evaluated. Diets classified as light contained higher TDF and IDF concentrations than did non-light diets. All canned diets were classified as low fat, despite providing up to 38% of calories as fat. CONCLUSIONS AND CLINICAL RELEVANCE: Diets provided a range of TDF concentrations and compositions; veterinarians should request TDF data from manufacturers, if not otherwise available. Consistent responses to dry and canned versions of the same diet cannot necessarily be expected, and diets with the same indications may not perform similarly. Many diets may not provide adequate fat restriction for treatment of dietary fat-responsive disease.

Comparison of perioperative morbidity and mortality rates in dogs with noninvasive adrenocortical masses undergoing laparoscopic versus open adrenalectomy.

OBJECTIVE: To describe the clinicopathologic features of a cohort of dogs with adrenocortical masses that underwent laparoscopic adrenalectomy and to compare perioperative morbidity and mortality rates in these dogs with rates for dogs that underwent open adrenalectomy for resection of similarly sized (maximal diameter, ≤ 5 cm) adrenocortical masses. DESIGN: Retrospective case series. ANIMALS: 48 client-owned dogs that underwent laparoscopic (n = 23) or open (25) adrenalectomy for noninvasive tumors (ie, tumors that did not invade the vena cava or other surrounding organs). Procedures-Medical records were reviewed. History, clinical signs, physical examination findings, clinicopathologic findings, imaging results, and surgical variables were recorded. A 3- or 4-port approach was used for laparoscopic adrenalectomy. Surgical time, perioperative complications, postoperative and overall hospitalization times, and perioperative deaths were recorded and compared between groups. RESULTS: The surgical method for 1 dog was converted from a laparoscopic to an open approach. Perioperative death occurred in no dogs in the laparoscopic group and 2 dogs in the open adrenalectomy group. Surgical time was shorter for laparoscopic (median, 90 minutes; range, 40 to 150 minutes) than for open (median, 120 minutes; range, 75 to 195 minutes) adrenalectomy. Laparoscopic adrenalectomy was associated with shorter hospitalization time and more rapid discharge from the hospital after surgery, compared with the open procedure. CONCLUSIONS AND CLINICAL RELEVANCE: With careful patient selection, laparoscopic adrenalectomy was associated with a low complication rate and low conversion rate for resection of adrenocortical masses as well as shorter surgical and hospitalization times, compared with open adrenalectomy.

Animal models of disease: classification and etiology of diabetes in dogs and cats.

Diabetes mellitus is a common disease in dogs and cats. The most common form of diabetes in dogs resembles type 1 diabetes in humans. Studies suggest that genetics, an immune-mediated component, and environmental factors are involved in the development of diabetes in dogs. A variant of gestational diabetes also occurs in dogs. The most common form of diabetes in cats resembles type 2 diabetes in humans. A major risk factor in cats is obesity. Obese cats have altered expression of several insulin signaling genes and glucose transporters and are leptin resistant. Cats also form amyloid deposits within the islets of the pancreas and develop glucotoxicity when exposed to prolonged hyperglycemia. This review will briefly summarize our current knowledge about the etiology of diabetes in dogs and cats and illustrate the similarities among dogs, cats, and humans.

Total dietary fiber composition of diets used for management of obesity and diabetes mellitus in cats.

OBJECTIVE: To determine total dietary fiber (TDF) composition of feline diets used for management of obesity and diabetes mellitus. DESIGN: Cross-sectional survey. SAMPLE: Dry veterinary (n = 10), canned veterinary (12), and canned over-the-counter (3) feline diets. PROCEDURES: Percentage of TDF as insoluble dietary fiber (IDF), high-molecular-weight soluble dietary fiber (HMWSDF), and low-molecular-weight soluble dietary fiber (LMWSDF) was determined. RESULTS: Median measured TDF concentration was greater than reported maximum crude fiber content in dry and canned diets. Median TDF (dry-matter) concentration in dry and canned diets was 12.2% (range, 8.11% to 27.16%) and 13.8% (range, 4.7% to 27.9%), respectively. Dry and canned diets, and diets with and without a source of oligosaccharides in the ingredient list, were not different in energy density or concentrations of TDF, IDF, HMWSDF, or LMWSDF. Similarly, loaf-type (n = 11) and gravy-type (4) canned diets differed only in LMWSDF concentration. Disparities in TDF concentrations among products existed despite a lack of differences among groups. Limited differences in TDF concentration and dietary fiber composition were detected when diets were compared on the basis of carbohydrate concentration. Diets labeled for management of obesity were higher in TDF concentration and lower in energy density than diets for management of diabetes mellitus. CONCLUSIONS AND CLINICAL RELEVANCE: Diets provided a range of TDF concentrations with variable concentrations of IDF, HMWSDF, and LMWSDF. Crude fiber concentration was not a reliable indicator of TDF concentration or dietary fiber composition. Because carbohydrate content is calculated as a difference, results suggested that use of crude fiber content would cause overestimation of both carbohydrate and energy content of diets.

Serum 17alpha-hydroxyprogesterone concentrations during the reproductive cycle in healthy dogs and dogs with hyperadrenocorticism.

OBJECTIVE: To determine concentrations of 17alpha-hydroxyprogesterone (17OHP) in serum of healthy bitches during various stages of the reproductive cycle and in bitches with hyperadrenocorticism and to compare the dynamics of 17OHP with those of progesterone. DESIGN: Prospective evaluation study. ANIMALS: 15 healthy sexually intact bitches and 28 spayed bitches with hyperadrenocorticism. PROCEDURES: 11 healthy bitches were evaluated during estrus, nonpregnant diestrus, and anestrus (group 1); 4 other healthy bitches were evaluated during pregnancy and after ovariohysterectomy (group 2). Cycle stages were determined via physical examination, vaginal cytologic evaluation, and serum progesterone concentration. Bitches with hyperadrenocorticism were evaluated once at the time of diagnosis (group 3). Serum hormone concentrations were determined with immunoassays. RESULTS: In group 1, the serum 17OHP concentration was significantly higher in diestrus (median, 1.8 ng/mL) than in estrus (median, 1.1 ng/mL) and anestrus (median, 0.2 ng/mL) and higher in estrus than in anestrus. Changes in serum progesterone concentrations accounted for 22% (estrus) or 23% (diestrus) of the variation in serum 17OHP concentrations. In group 2, 17OHP and progesterone concentrations were significantly higher during pregnancy than after ovariohysterectomy. The serum 17OHP concentration in group 3 was significantly lower (median, 0.2 ng/mL) than in group 1 in estrus and diestrus and in group 2 during pregnancy (median, 0.7 ng/mL) but was not different from 17OHP concentrations in anestrus or after ovariohysterectomy (median, 0.2 ng/mL). CONCLUSIONS AND CLINICAL RELEVANCE: Serum 17OHP concentrations in healthy bitches increased during estrus, diestrus, and pregnancy and at those times were higher than in spayed bitches with hyperadrenocorticism.

Evaluation of six portable blood glucose meters for measuring blood glucose concentration in dogs.

OBJECTIVE: To evaluate accuracy of 6 portable blood glucose meters (PBGMs) by comparing results of these meters with results obtained with a reference chemistry analyzer. DESIGN: Evaluation study. ANIMALS: 49 dogs (158 blood samples). Procedures-Venous blood samples were tested with the 6 PBGMs, and results were compared with results of a commercially available analyzer that used a reference method based on the hexokinase reaction. RESULTS: Plasma glucose concentrations obtained with the reference analyzer ranged from 41 to 639 mg/dL. There were significant correlations between blood glucose concentrations obtained with the 6 PBGMs and plasma glucose concentrations obtained with the reference analyzer (r > or = 0.96). However, for all 6 PBGMs, results differed from results for the reference analyzer, with the difference increasing as plasma glucose concentration increased. Significant differences in bias were found among meters. For 142 samples classified as hypoglycemic, euglycemic, or hyperglycemic on the basis of results of the reference analyzer, the percentage of samples that were misclassified on the basis of results of the PBGMs ranged from 2.1% to 38.7%. CONCLUSIONS AND CLINICAL RELEVANCE: Results of the present study suggested that there were substantial differences in the accuracy of currently available PBGMs when used to determine blood glucose concentration in dogs.

Evaluation of urine specific gravity and urine sediment as risk factors for urinary tract infections in cats.

BACKGROUND: It has been suggested that diseases that promote isosthenuria predispose to urinary tract infections because of a lack of the common bacteriostatic properties present in concentrated urine. OBJECTIVES: The purpose of this study was to assess the clinicopathologic risk factors for positive urine culture outcome in cats with chronic kidney disease (CKD), diabetes mellitus (DM), uncontrolled hyperthyroidism (HT), or lower urinary tract disease (LUTD). METHODS: For this retrospective study, medical records of all cats in which a urinalysis and aerobic bacterial urine culture were performed between January 1995 and December 2002 were reviewed. Signalment, body weight, and clinicopathologic data were recorded. Based on the medical records, cats were diagnosed with CKD, DM, HT, or LUTD. Prevalence odds ratios and 95% confidence intervals were calculated using logistic regression. Multivariate models were created for each variable of interest while controlling for the confounding effect of disease group. RESULTS: Six hundred fourteen cats met the criteria for inclusion in the study. Overall, positive urine cultures were identified in 16.9% of cats with CKD, 13.2% of cats with DM, 21.7% of cats with HT, and 4.9% of cats with clinical signs of LUTD. Decreasing urine specific gravity was not associated with positive urine culture when controlled for disease but pyuria, bacteriuria, and hematuria were all associated with positive urine culture outcome. Persians, females, increasing age, and decreasing body weight were all associated with positive urine culture outcome. CONCLUSIONS: Performing a urine culture sample based solely on the presence of isosthenuria does not seem warranted. Further studies are warranted to help identify host predisposing factors for urinary bacterial colonization in cats with these diseases.