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.

Incorporation of exercise, using an underwater treadmill, and active client education into a weight management program for obese dogs.

Physical activity improves outcome of weight loss in obese humans, but limited information exists for dogs. Eight obese dogs (body condition score 5/5), of various breeds and genders, undertook a 3-month weight-loss program which included exercise using lead walks and underwater treadmill exercise. The median number of treadmill exercise sessions per dog was 13 (range: 5 to 17). Median distance walked per session was 0.97 km (range: 0.05 to 2.7 km) (0.6 miles; range: 0.03 to 1.70 miles) and this increased sequentially over the course of the study (P < 0.001). Mean [± standard deviation (s)] percentage of starting weight loss over the 3 mo was 18.9 ± 5.44%, equivalent to a rate of weight loss of 1.5 ± 0.43% per week. Thoracic and abdominal girth also declined significantly during the program (P < 0.0001 for both). This study demonstrates the potential benefit of including an organized exercise regimen, utilizing an underwater treadmill, in conventional canine weight management programs.

Nutritional management of chronic renal disease in dogs and cats.

Chronic renal disease is a leading cause of death in dogs and cats. Recent clinical studies show that nutrition plays a key role in improving quality of life and life expectancy of these patients. Typical nutritional interventions include modifying the protein, phosphorus, and lipid concentrations. Nutritional therapy, however, does not simply mean changing the diet; consideration must also be given to ensuring adequate caloric intake and to the method of feeding. Monitoring the effects of the dietary therapy is also crucial to ensure that the patients are responding appropriately to the selected nutritional modifications. Nutritional management must be coordinated with medical management for long term successful treatment.

Pharmacokinetics and clinical utility of sodium bromide (NaBr) as an estimator of extracellular fluid volume in horses.

The purpose of this study was to describe the pharmacokinetics of bromide in horses and to evaluate the corrected bromide space as an indicator of extracellular fluid volume (ECFV) in horses after the administration of a single dose of bromide by intravenous infusion. Sodium bromide (30 mg/kg of body weight, IV) was administered to 6 clinically healthy mares over a period of 3 minutes. Blood samples were collected before infusion and at intervals between 0.5 hours and 53 days after infusion. Mean elimination half-life (harmonic mean) was 126 hours (5.2 days), clearance was 1.4 +/- 0.09 mL/(kg x h), area under the curve was 17,520 +/- 1,100 microg x h/mL. and volume of distribution (steady state) was 0.255 +/- 0.015 L/kg. The mean corrected bromide space was determined from the volume of distribution (steady state) and the serum concentrations of bromide at equilibration. Corrected bromide space, an estimate of ECFV, was 0.218 +/- 0.01 L/kg. The conclusion was made that ECFV of horses can be estimated by measuring bromide concentrations in a preinfusion serum sample and a sample obtained 5 hours after the administration of bromide.

Use of multifrequency bioelectrical impedance analysis for estimation of total body water and extracellular and intracellular fluid volumes in horses.

OBJECTIVE: To evaluate the use of multifrequency bioelectrical impedance analysis (MF-BIA) for estimating total body water (TBW), extracellular fluid volume (ECFV), and intracellular fluid volume (ICFV) in horses. ANIMALS: 9 healthy mares. PROCEDURE: TBW and ECFV were measured by use of deuterium oxide and sodium bromide dilution techniques, respectively. Intracellular fluid volume was calculated as the difference between TBW and ECFV. Concurrently, MF-BIA recordings were obtained by use of 4 anatomic electrode positions and 3 measurements of length. Models for MF-BIA data were created for all combinations of length and anatomic electrode position. Models were evaluated to determine the position-length configuration that provided the most consistent estimates of TBW, ECFV, and ICFV, compared with values determined by use of the dilution techniques. RESULTS: Positioning electrodes over the ipsilateral carpus and tarsus and use of height at the tuber sacrale for length provided the closest estimate between values for TBW, ECFV, and ICFV predicted by use of MF-BIA and measured values obtained by dilutional techniques. This model had the narrowest 95% limits of agreement. CONCLUSIONS AND CLINICAL RELEVANCE: MF-BIA techniques have been used to predict changes in TBW, ECFV, and ICFV in healthy and diseased humans. Results reported in this study provide an equine-specific model to serve as the basis for further evaluation of MF-BIA in horses with altered fluid states. The MF-BIA techniques have a number of potential applications for use in horses, including evaluation of exercise physiology, pharmacologic studies, and critical-care management.

A moderate fat, low-energy dry expanded diet reduces gain in body condition score when fed as part of a post neutering weight-control regimen in growing pet cats.

Neutering of cats has been associated with significant weight gain in the weeks following surgery. The present study aimed to evaluate the effectiveness of a moderate fat, low-energy dry expanded diet in reducing weight gain in growing pet cats when fed as part of a weight-control regimen over the 6 months post-neutering. Cats in participating primary care veterinary hospitals were enrolled at neutering and assigned to receive one of the two dietary treatments based on the hospital of origin. Owners of cats in the treatment group were instructed to feed the trial diet at maintenance (324·7 kJ/kg BW(0·711) per d). Instructions for the control group were to feed the cat's regular diet according to the manufacturer's recommendations. Body weight and condition were evaluated by veterinarians at enrolment, 2-weeks, and 1-4 and 6 months after surgery. Body condition score (five-point scale) was compared between enrolment and each subsequent visit, controlling for enrolment age and sex. Percentage change in body weight was evaluated via multivariate mixed modelling to account for repeated measures. A total of 187 cats (eighty-seven females and 100 males) with a mean age of 5·2 (sd 0·8) months and mean weight of 2·8 (sd 0·6) kg from fifty-one hospitals completed the trial. The odds of being scored as overweight were 4·1 times as great for cats in the control v. treatment groups (95 % CI 2·1, 8·2). Percentage change in body weight differed significantly with enrolment age (P = 0·007) and approached significance between diet groups (P = 0·08). Cats fed the trial diet had a significantly reduced incidence of overweight in the 6 months following neutering.

Effect of age at gonadectomy on the probability of dogs becoming overweight.

OBJECTIVE: To determine whether gonadectomy or age at gonadectomy was associated with the risk that dogs would subsequently become overweight. DESIGN: Retrospective cohort study. ANIMALS: 1,930 dogs gonadectomized between 1998 and 2001 at ≤ 6 months of age (n = 782), > 6 months to ≤ 1 year of age (861), or > 1 to ≤ 5 years of age (287) and 1,669 sexually intact dogs. PROCEDURES: Dogs were followed-up through medical records for ≥ 10 years or until a diagnosis of overweight (defined as overweight, obese, or having a body condition score ≥ 4/5) was recorded. Information extracted included age at study entry, sex, breed, breed-size category, hospital visit frequency, and diagnosis (yes or no) of overweight or diseases that might affect body condition. Relative risk of a diagnosis of overweight was assessed among age groups of gonadectomized dogs and between gonadectomized and sexually intact dogs. RESULTS: No difference was detected among dogs grouped according to age at gonadectomy with respect to the risk of being overweight. This risk was significantly greater in gonadectomized dogs than in sexually intact dogs, but only during the first 2 years after gonadectomy. Sexually intact male dogs were approximately 40% less likely to have this diagnosis (hazard ratio, 0.61; 95% confidence interval, 0.52 to 0.72) than were sexually intact female dogs; no difference in risk between the sexes was evident for gonadectomized dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Gonadectomized dogs had a greater risk of being overweight than did sexually intact dogs, but this risk was not influenced by age at gonadectomy. Opportunities exist for veterinarians to provide counseling during the first years after gonadectomy to help dogs maintain a healthy weight.

Nutritional considerations for the dialytic patient.

Nutritional therapy has a key role in the conservative management of renal disease. This role is even more vital with the advent of advanced renal replacement therapies to support patients with life threatening severe oliguric or anuric acute uremia or the International Renal Interest Society stage IV chronic kidney disease. Nutritional assessment and institution of nutritional support is crucial because dialysis only partially alleviates uremic anorexia. Dialytic patients have a higher risk of protein calorie, iron, zinc, vitamin B6, vitamin C, folic acid, 1,25-dihydroxycholecalciferol, and carnitine malnutritions.