L-Carnitine metabolism, protein turnover and energy expenditure in supplemented and exercised Labrador Retrievers.

L-Carnitine is critical for protection against bioaccumulation, long-chain fatty acid transportation and energy production. Energy production becomes important as the body maintains lean mass, repairs muscles and recovers from oxidative stress. The aim was to investigate the effects of supplemented L-carnitine on protein turnover (PT), energy expenditure (EE) and carnitine metabolism in muscle/serum of Labrador Retrievers. In a series of experiments, all dogs were fed a low-carnitine diet and sorted into one of two groups: L-carnitine (LC) supplemented daily with 125 mg L-carnitine and 3.75 g sucrose or placebo (P) supplemented with 4 g sucrose daily. The experiments consisted of analyses of muscle/serum for L-carnitine content (EXP1), a protein turnover experiment (EXP2) and analysis of substrate utilization via indirect calorimetry (EXP3). EXP1: 20 Labradors (10 M/10 F) performed a 13 week running regimen. L-Carnitine content was analysed in the serum and biceps femoris muscle before/after a 24.1 km run. LC serum had higher total (p < .001; p = .001), free (p < .001; p = .001) and esterified (p = .001; p = .003) L-carnitine pre- and post-run respectively. LC muscle had significantly higher free L-carnitine post-run (p = .034). EXP2: 26 Labs (13 M/13 F) performed a 60-day running regimen. For the final run, half of the Labradors from each treatment rested and half ran 24.1 km. Twenty-four Labradors received isotope infusion, and then, a biopsy of the biceps femoris of all 26 Labradors was taken to determine PT. Resting/exercised LC had a lower fractional breakdown rate (FBR) versus P group (p = .042). LC females had a lower FBR v. P females (p = .046). EXP3: Respiration of 16 Labradors (8 M/8 F) was measured via indirect calorimetry over 15 week. All dogs ran on a treadmill for 30 min at 30% VO2 max (6.5 kph), resulting in higher maximum and mean EE in LC females v. P females (p = .021; p = .035). Implications for theory, practice and future research are discussed.

Pharmacokinetics of levofloxacin after single intravenous, oral and subcutaneous administration to dogs.

The pharmacokinetic properties of the fluoroquinolone levofloxacin (LFX) were investigated in six dogs after single intravenous, oral and subcutaneous administration at a dose of 2.5, 5 and 5 mg/kg, respectively. After intravenous administration, distribution was rapid (T½dist 0.127 ± 0.055 hr) and wide as reflected by the volume of distribution of 1.20 ± 0.13 L/kg. Drug elimination was relatively slow with a total body clearance of 0.11 ± 0.03 L kg-1  hr-1 and a T½ for this process of 7.85 ± 2.30 hr. After oral and subcutaneous administration, absorption half-life and Tmax were 0.35 and 0.80 hr and 1.82 and 2.82 hr, respectively. The bioavailability was significantly higher (p Ë‚ 0.05) after subcutaneous than oral administration (79.90 vs. 60.94%). No statistically significant differences were observed between other pharmacokinetic parameters. Considering the AUC24 hr /MIC and Cmax /MIC ratios obtained, it can be concluded that LFX administered intravenously (2.5 mg/kg), subcutaneously (5 mg/kg) or orally (5 mg/kg) is efficacious against Gram-negative bacteria with MIC values of 0.1 µg/ml. For Gram-positive bacteria with MIC values of 0.5 µg/kg, only SC and PO administration at a dosage of 5 mg/kg showed to be efficacious. MIC-based PK/PD analysis by Monte Carlo simulation indicates that the proposed dose regimens of LFX, 5 and 7.5 mg/kg/24 hr by SC route and 10 mg/kg/24 hr by oral route, in dogs may be adequate to recommend as an empirical therapy against S. aureus strains with MIC ≤ 0.5 µg/ml and E. coli strains with MIC values ≤0.125 µg/ml.

Catestatin, vasostatin, cortisol, and visual analog scale scoring for stress assessment in healthy dogs.

The neuroendocrine glycoprotein chromogranin A is a useful biomarker for stress in humans. Chromogranin A epitopes catestatin and vasostatin can be measured in dogs using radioimmunoassays. The objective of this study was to evaluate catestatin and vasostatin as canine stress biomarkers in a clinical setting. Blood and saliva were collected from 33 healthy dogs that were familiar with sampling procedures and the animal hospital environment (control group) and 30 healthy dogs that were unacquainted (stress group). During sampling, stress behavior was scored by the same observer using visual analog scale (VAS). Plasma was analyzed for catestatin and vasostatin, serum for cortisol, and saliva for catestatin. Differences between groups were analyzed using two-sample t-tests and P<0.05 was considered significant. Stress behavior VAS score in the control group was significantly lower than in the stress group during blood (P=0.002) and saliva (P=0.0009) sampling. Serum cortisol and saliva catestatin concentrations in the stress group were higher than the control group (P=0.003 and P<0.0001, respectively). Serum cortisol concentrations were correlated with those of saliva (r=0.34, P=0.04) and plasma catestatin (r=0.29, P=0.03). Plasma catestatin and vasostatin did not differ significantly between groups. In conclusion, concentrations of saliva catestatin, and serum cortisol, and stress behavior VAS scores were significantly higher in the stress group. The results indicate that saliva catestatin may be useful as a biomarker for acute psychological stress in dogs.

Coat and claws as new matrices for noninvasive long-term cortisol assessment in dogs from birth up to 30 days of age.

The last stage of fetal development and the neonatal period represent the most critical phases for the mammals' offspring. In the dog, the knowledge about the final intrauterine fetal development and biology, as well as about the neonatal physiology, remains scarce. Hormonal changes occurring in the last intrauterine fetal phase and during the early neonatal age are still not completely clear, probably because of the invasiveness related to the collection of the more common biological matrix, represented by circulating blood. Toward term of pregnancy, during parturition, and after birth, the hypothalamic-pituitary-adrenal axis is a key system regulating several physiological processes, and its activity was previously investigated by blood analysis, considered an invasive procedure providing a single-point measurement. In respect to animal welfare, and for a more correct long-term retrospective investigation, noninvasive hormonal studies were performed firstly on the hair of humans and coat of animals and, more recently, in the nails of human beings. This study was aimed to assess cortisol (COR) in coat and claws of newborn puppies and to evaluate the possible influence of the newborn gender, breed body size, and age on coat and claws COR concentrations. The results obtained from 165 newborn puppies evidenced that coat and claws COR levels were highly correlated each other (P < 0.0001), although the COR accumulation in the two matrices was different in relation to the class of age. Moreover, the puppies age influenced both coat and claws COR concentrations (P < 0.05), with premature puppies showing higher values when compared to term born-dead puppies or puppies dead between 1 and 30 days of age. The present study reported that COR is quantifiable in coat and claws of newborn dogs. Moreover, both matrices appear as useful tools for new, noninvasive, long-term perinatal and neonatal researches also in canine species.

Pharmacokinetic modeling and Monte Carlo simulation of ondansetron following oral administration in dogs.

Ondansetron is a potent antiemetic drug that has been commonly used to treat acute and chemotherapy-induced nausea and vomiting (CINV) in dogs. The aim of this study was to perform a pharmacokinetic analysis of ondansetron in dogs following oral administration of a single dose. A single 8-mg oral dose of ondansetron (Zofran(®) ) was administered to beagles (n = 18), and the plasma concentrations of ondansetron were measured by liquid chromatography-tandem mass spectrometry. The data were analyzed by modeling approaches using ADAPT5, and model discrimination was determined by the likelihood-ratio test. The peak plasma concentration (Cmax ) was 11.5 ± 10.0 ng/mL at 1.1 ± 0.8 h. The area under the plasma concentration vs. time curve from time zero to the last measurable concentration was 15.9 ± 14.7 ng·h/mL, and the half-life calculated from the terminal phase was 1.3 ± 0.7 h. The interindividual variability of the pharmacokinetic parameters was high (coefficient of variation > 44.1%), and the one-compartment model described the pharmacokinetics of ondansetron well. The estimated plasma concentration range of the usual empirical dose from the Monte Carlo simulation was 0.1-13.2 ng/mL. These findings will facilitate determination of the optimal dose regimen for dogs with CINV.

Evaluation of the oral (13)C-bicarbonate technique for measurements of energy expenditure in dogs before and after body weight reduction.

BACKGROUND: Overweight and obesity are the most common nutritional disorders in dogs and may lead to various secondary diseases and decreased lifespan. In obesity research, measurement of energy expenditure (EE) and determination of the energy requirements are essential. The objective with this study was to validate and evaluate the suitability of the oral (13)C-bicarbonate technique (o(13)CBT) for measuring EE in dog obesity studies. A further objective was to investigate the impact of body weight (BW) reduction and changes in body composition on the EE when measured under conditions corresponding to the basal metabolic rate (BMR). RESULTS: The EE in five privately owned, overweight dogs was measured simultaneously with the o(13)CBT and indirect calorimetry (IC) for comparison of the results. Two measurements per dog were performed under the same standardised conditions (i.e. fasted and resting state) at the start, and after completing a 12-week BW reduction program. Additionally, measurements of body composition by Dual-energy X-ray absorptiometry (DEXA) were conducted at the beginning and at the end of the BW reduction program. There were no differences in EE results obtained by the o(13)CBT and IC. Overweight and the BW reduction did not affect the estimates for the respiratory quotient (RQ) or the recovery factor for the (13)C-tracer (RF), both needed when using the o(13)CBT. The dogs lost 16% (SD ± 2.0) of their initial BW in reduced fat mass (P < 0.001), whereas fat free mass (FFM) remained unchanged. There was no effect of the BW reduction on the determined EE expressed in kJ/kg BW/d, or in kJ/kg BW(0.75)/d. However, EE was lower (P < 0.001) after the BW reduction program when expressed in relation to FFM (kJ/kg FFM/d). CONCLUSIONS: Results from the present study show that the o(13)CBT can be a used in obesity research to determine EE in fasted dogs and under resting conditions. Furthermore, the results suggest that the BMR does not change with reduced BW in overweight dogs as long as the FFM remains unchanged. This indicates that the BMR to maintain one gram of fat is equal to maintaining one gram of FFM in overweight dogs.

Validation of an eight parameter immunophenotyping panel in adult canines for assessment of immunotoxicity.

Analysis of peripheral blood leukocyte populations by flow cytometry in adult beagles is a critical component of immunotoxicity assessment in regulated pre-clinical toxicology studies. In this study, data is presented utilizing a single panel, six-color method to simultaneously enumerate absolute cell counts and determine the relative percentage of leukocytes. A GLP validation was performed to determine intra- and inter-assay variance, inter-instrument variance, and pre- and post-fixation stability for the target populations. The results demonstrated all samples met acceptance criteria, CV values less than 25%, for all precision and stability intervals assessed. The intra and inter-assay data demonstrated the single panel method generated acceptable precision. Furthermore, stability results indicated whole blood samples and processed samples may be stored without a statistically significant difference in the data compared to samples immediately processed and analyzed after blood collection. This assay will provide researchers a more precise and efficient tool to evaluate the immunotoxic effects of a test article on canine peripheral blood leukocytes during pre-clinical drug testing.

Sonographic assessment of vessel invasion by cervical masses in dogs / Avaliação ultrassonográfica da invasão vascular por massas cervicais em cães

Tumor invasion of the vessels displays both therapeutic and prognostic implications and represents a challenge for head and neck surgeons. Although previous research has shown that ultrasound can detect such invasions, accurate sonographic parameters to do so have not yet been established. We sought to determine sonographic criteria which are able to characterize these invasions. A high-resolution transducer was used to perform ultrasound examinations of 15 patients selected from a group with inconclusive radiography and computed tomography diagnosis. We found that encasement of the vessel, tumor immobility or fixation in the vessel wall, and narrowing and/or deformity of the lumen were the best criteria. Indeed, when loss of hyperechoic interface of the vessel wall was used as a single criterion it generated false positive results. This study shows that a combination of parameters can be used to provide the best sensitivity and specificity values to produce conclusive diagnosis of vessel invasion by tumors in the cervical region.

Determinaram-se critérios ultrassonográficos capazes de caracterizar a invasão vascular por tumores em cães. Utilizaram-se transdutores de alta resolução para os exames ultrassonográficos realizados em 15 pacientes, selecionados de um grupo submetido previamente à radiografia e tomografia computadorizada, com resultados inconclusivos. Os melhores critérios encontrados foram: encarceramento do vaso, imobilidade do tumor ou aderência na parede vascular e estreitamento ou deformidade luminal. A perda de definição da interface hiperecoica da parede vascular quando foi usada como critério isolado produziu resultados falso positivos. O estudo demonstrou que uma combinação de parâmetros pode ser usada para aumentar a sensibilidade e especificidade diagnóstica, produzindo diagnósticos mais conclusivos e precisos pra definir a invasão vascular por tumores na região cervical ventral.

Assessment of blood pool, soft tissue, and skeletal uptake of sodium fluoride F 18 with positron emission tomography-computed tomography in four clinically normal dogs.

OBJECTIVE: To determine the ideal interval to image acquisition after IV injection of sodium fluoride F 18 ((18)F-NaF) and evaluate biodistribution of the radiopharmaceutical in clinically normal skeletally immature dogs. ANIMALS: 4 female dogs. PROCEDURES: Each dog was anesthetized for evaluation with a commercial hybrid positron emission tomography (PET)-CT instrument. A low-radiation dose, whole-body CT scan was acquired first. An IV injection of (18)F-NaF (0.14 mCi/kg) was administered, and a dynamic PET scan centered over the heart and liver was acquired during a period of 120 minutes. Uptake of (18)F-NaF in the blood pool, soft tissues, and skeletal structures was evaluated via region of interest analysis to derive standardized uptake values and time-activity curves, which were used to determine the optimal postinjection time for skeletal image acquisition. Biodistribution was also assessed from a final whole-body PET-CT scan acquired after the dynamic scan. RESULTS: Time-activity curves revealed a rapid decrease in the amount of radiopharmaceutical in the blood pool and soft tissues and a rapid increase in the amount of radiopharmaceutical in bones soon after injection. At 50 minutes after injection, the greatest difference in uptake between soft tissues and bones was detected, with continued subtle increase in uptake in the bones. Uptake of (18)F-NaF was slightly increased at growth plates and open ossification centers, compared with that at other parts of the bone. CONCLUSIONS AND CLINICAL RELEVANCE: At 50 minutes after IV injection of (18)F-NaF at the dose evaluated, PET-CT yielded excellent bone-to-background ratio images for evaluation of the skeletal system in dogs.

Assessment of plasma uracil-to-dihydrouracil concentration ratio as an indicator of dihydropyrimidine dehydrogenase activity in clinically normal dogs and dogs with neoplasia or renal insufficiency.

OBJECTIVE: To determine and compare the ratio of uracil (U) to dihydrouracil (UH(2)) concentrations in plasma as an indicator of dihydropyrimidine dehydrogenase activity in clinically normal dogs and dogs with neoplasia or renal insufficiency. ANIMALS: 101 client- and shelter-owned dogs. PROCEDURES: Study dogs included 74 clinically normal dogs, 17 dogs with neoplasia, and 10 dogs with renal insufficiency. For each dog, a blood sample was collected into an EDTA-containing tube; plasma U and UH(2) concentrations were determined via UV high-performance liquid chromatography, and the U:UH(2) concentration ratio was calculated. Data were compared among dogs grouped on the basis of sex, clinical group assignment, reproductive status (sexually intact, spayed, or castrated), and age. RESULTS: Mean ± SEM U:UH(2) concentration ratio for all dogs was 1.55 ± 0.08 (median, 1.38; range, 0.4 to 7.14). In 14 (13.9%) dogs, the U:UH(2) concentration ratio was considered abnormal (ie, > 2). Overall, mean ratio for sexually intact dogs was significantly higher than that for neutered dogs; a similar difference was apparent among males but not females. Dogs with ratios > 2 and dogs with ratios ≤ 2 did not differ significantly with regard to sex, clinical group, reproductive status, or age. CONCLUSIONS AND CLINICAL RELEVANCE: Determination of the U:UH(2) concentration ratio was easy to perform. Ratios were variable among dogs, possibly suggesting differences in dihydropyrimidine dehydrogenase activity. However, studies correlating U:UH(2) concentration ratio and fluoropyrimidine antimetabolite drug tolerability are required to further evaluate the test's validity and its appropriate use in dogs.

Pharmacokinetic modeling of doxorubicin pharmacokinetics in dogs deficient in ABCB1 drug transporters.

BACKGROUND: The identification of dogs defective in ATP-binding cassette transporter B1 (ABCB1, MDR1) activity has prompted questions regarding pharmacokinetics (PK), efficacy and toxicity of ABCB1 substrates in these dogs. HYPOTHESIS/OBJECTIVES: Dogs defective in ABCB1 activity (ABCB1(null)) have doxorubicin (DOX) PK different from that of normal dogs (ABCB1(wt)). Utilization of a physiologically based pharmacokinetic (PBPK) model allows computer simulation to study this polymorphism's impact on DOX PK. ANIMALS: None. METHODS: A virtual ABCB1(wt) dog population was generated and DOX distribution, elimination, and metabolism simulated by PBPK modeling. An in silico population of virtual dogs was generated by Monte Carlo simulation, with variability in physiologic and biochemical parameters consistent with the dog population. This population was used in the PBPK model. The ABCB1 components of the model were inactivated to generate an ABCB1(null) population and simulations repeated at multiple doses. Resulting DOX levels were used to generate PK parameters. RESULTS: DOX exposures in the ABCB1(null) population were increased in all simulated tissues including serum (24%) and gut (174%). Estimated dosages in the ABCB1(null) population to approximate exposure in the ABCB1(wt) population at a dose of 30 mg/m(2) were 24.8 +/- 3.5 mg/m(2) for serum and 10.7 +/- 5.9 mg/m(2) for gut. CONCLUSIONS AND CLINICAL IMPORTANCE: These results suggest that serum DOX concentrations are not indicative of tissue exposure, especially those with appreciable ABCB1 activity, and that gastrointestinal (GI) toxicosis would be dose limiting in ABCB1(null) populations. Dosage reductions necessary to prevent GI toxicosis likely result in subtherapeutic concentrations, thereby reducing DOXs efficacy in ABCB1(null) dogs.

Assessment of clotrimazole gels for in vitro stability and in vivo retention in the frontal sinus of dogs.

OBJECTIVE: To evaluate the stability and retention of viscous formulations of the antifungal drug clotrimazole in vitro and to evaluate retention times, absorption, and histologic response to these compounds when placed in the frontal sinus of dogs. ANIMALS: 6 male Beagles. PROCEDURES: 1% clotrimazole gels were formulated with hydroxypropyl cellulose, poloxamer, and carboxymethylcellulose sodium bases. Commercially available 1% clotrimazole creams were also evaluated. Each compound was incubated at 37 degrees C in a funnel. Volume retained and clotrimazole stability were evaluated for 4 weeks. Six compounds were then chosen for in vivo evaluation. The frontal sinuses of 6 dogs were filled with 1 of the 6 compounds. Computed tomographic evaluation was performed weekly for up to 4 weeks to evaluate gel retention. Blood samples were collected to evaluate clotrimazole absorption. Following euthanasia, sinuses were examined histologically. RESULTS: Commercially available clotrimazole creams were not retained in funnels in vitro. In vivo, hydroxypropyl cellulose- and carboxymethylcellulose-based gels resulted in the most severe inflammatory response and were retained the longest. Poloxamer-based gels had a shorter retention time and were associated with less inflammation. Clotrimazole was minimally absorbed. Despite a marked inflammatory response to several of the clotrimazole-containing gels, no notable adverse clinical responses were observed. CONCLUSIONS AND CLINICAL RELEVANCE: Poloxamer gels had the most promise for improving drug contact within the frontal sinus of dogs, while limiting the inflammatory response. Poloxamer gels have the additional benefit of improved handling as a result of reverse gelation (ie, they gel when warmed to 37 degrees C).

Assessment of diuretic effects and changes in plasma aldosterone concentration following oral administration of a single dose of furosemide or azosemide in healthy dogs.

OBJECTIVE: To determine the diuretic effects and changes in plasma aldosterone concentration (PAC) following oral administration of a single dose of furosemide or azosemide in healthy dogs. ANIMALS: 8 mixed-breed dogs. PROCEDURES: A single dose of furosemide (2 mg/kg), azosemide (1, 5, or 10 mg/kg), or placebo (bifidobacterium [1 mg/kg]) was administered orally (in random order at 7-day intervals) to each dog (5 treatments/dog). Urine and blood samples were collected before (2 hours after evacuation of the urinary bladder; baseline) and at intervals for 24 hours after drug treatment to assess urine volume and plasma and urine biochemical variables. RESULTS: Compared with baseline values, treatment with furosemide and azosemide (5 and 10 mg/kg) increased urine output for 1 to 2 hours and 2 to 4 hours, respectively. The 24-hour urine volume and urinary sodium excretion were significantly increased following furosemide and azosemide (5 and 10 mg/kg) treatments, compared with effects of placebo; these increases were dose dependent for azosemide, and increases were similar for furosemide and the 5 mg/kg dose of azosemide. Compared with other treatments, 24-hour urinary potassium excretion was significantly increased with azosemide at 10 mg/kg. Azosemide (5 and 10 mg/kg) significantly increased plasma total protein concentration and decreased plasma potassium concentration, compared with baseline values. Compared with the effect of placebo, PAC was significantly increased by furosemide and the 10 mg/kg dose of azosemide. CONCLUSIONS AND CLINICAL RELEVANCE: In healthy dogs, a moderate dose of azosemide caused sufficient diuretic action and increased PAC to a lesser extent than furosemide.

Assessment of three automated assays for C-reactive protein determination in dogs.

OBJECTIVE: To determine the characteristics of an automated canine C-reactive protein (CRP) assay and evaluate 2 human CRP assays for use in dogs. Animals-56 client-owned dogs with pyometra and 11 healthy control dogs. PROCEDURES: Samples from 11 dogs with high (> 100 mg/L) or low (< 10 mg/L) CRP concentrations (determined by use of a canine ELISA) were evaluated by use of the automated canine CRP assay. Intra- and interassay imprecision was determined (by use of those 2 plasma pools), and assay inaccuracy was assessed by use of logistic regression analysis of results obtained via ELISA and the automated canine CRP assay. Two automated human CRP assays were used to measure plasma CRP concentration in 10 dogs. RESULTS: By use of the ELISA, mean +/- SD plasma CRP concentration was 96.1 +/- 38.5 mg/L and 10.1 +/- 23.2 mg/L in dogs with pyometra and control dogs, respectively. The automated canine assay had intra-assay coefficients of variation (CVs) of 7.8% and 7.9%, respectively, and interassay CVs of 11.1% and 13.1%, respectively. Results from the automated assay were highly correlated with results obtained via ELISA. The human assay results did not exceed 0.4 mg/L in any dog. CONCLUSIONS AND CLINICAL RELEVANCE: The automated canine CRP assay had less interassay imprecision, compared with the ELISA. The 2 human CRP assays were not suitable for analysis of canine plasma samples. The automated canine CRP assay was more precise than the ELISA for serial evaluations of plasma CRP concentration in dogs.

Resting energy expenditure and body composition of Labrador Retrievers fed high fat and low fat diets.

A high dietary fat intake may be an important environmental factor leading to obesity in some animals. The mechanism could be either an increase in caloric intake and/or a decrease in energy expenditure. To test the hypothesis that high fat diets result in decreased resting energy expenditure (REE), we measured REE using indirect calorimetry in 10-adult intact male Labrador Retrievers, eating weight-maintenance high-fat (HF, 41% energy, average daily intake: 8018 +/- 1247 kJ/day, mean +/- SD) and low-fat (LF, 14% energy, average daily intake: 7331 +/- 771 kJ/day) diets for a 30-day period. At the end of each dietary treatment, body composition measurements were performed using dual-energy X-ray absorptiometry. The mean +/- SD REE was not different between diets (4940 +/- 361 vs. 4861 +/- 413 kJ/day on HF and LF diets respectively). Measurements of fat-free mass (FFM) and fat mass (FM) also did not differ between diets (FFM: 26.8 +/- 2.3 kg vs. 26.3 +/- 2.5 kg; FM: 3.0 +/- 2.3 vs. 3.1 +/- 1.5 kg on HF and LF diets respectively). In summary, using a whole body calorimeter, we found no evidence of a decrease in REE or a change in body composition on a HF diet compared with LF diet.

Owner impressions of three premium diets fed to healthy adult dogs.

OBJECTIVE: To determine owner impressions of 3 premium canine diets when factors such as price and retail source were removed; to compare body condition scores (BCSs) assigned by owners versus a veterinarian; and to determine consistency of owner impressions of diets when owners were not informed that they were feeding the same diet during 2 consecutive periods. DESIGN: Randomized controlled trial. ANIMALS: 44 healthy adult dogs. PROCEDURE: During the initial 12 months of the study, dogs were each fed 3 premium diets for 4 months in random order. After feeding each diet for 1 and 4 months, owners completed questionnaires regarding palatability of the diet; the dog's attitude, energy level, fecal consistency, frequency of defecation, hair coat quality, and BCS; and whether they would feed the diet if available commercially. During the last 4 months of the study, owners fed the same diet they had been feeding during the previous 4 months. RESULTS: Scores for most variables did not differ among diets. However, mean BCS assigned by owners was significantly lower than mean BCS assigned by an investigator, with a moderate correlation between scores. When asked at the end of the third and fourth study periods whether they would consider feeding the diet long-term, 12 of the 44 (27%) owners gave inconsistent responses. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that when unaware of retail price and source, owners have similar impressions of 3 premium diets fed to healthy adult dogs, suggesting that factors other than the diets themselves may affect owner impressions. Owners also underestimate their dog's BCS.

Assessment of a von Frey device for evaluation of the antinociceptive effects of morphine and its application in pharmacodynamic modeling of morphine in dogs.

OBJECTIVE: To assess the use of a von Frey device as a mechanical nociceptive stimulus for evaluation of the antinociceptive effects of morphine in dogs and its potential application in the pharmacodynamic modeling of morphine in that species. ANIMALS: 6 healthy Beagles. PROCEDURE: von Frey thresholds were measured in all dogs before and at intervals after they received no treatment (control dogs) and i.v. administration of morphine sulfate (1 mg/kg; treated dogs) in a crossover study. The von Frey device consisted of a rigid tip (0.5 mm in diameter) and an electronic load cell; the operator was unaware of recorded measurements. RESULTS: Application of the von Frey device was simple and well tolerated by all dogs and caused no apparent tissue damage. No significant changes in thresholds were detected in the control dogs at 8 hourly measurements, indicating a lack of acquired tolerance, learned aversion, or local hyperalgesia. When assessed as a group, treated dogs had significantly high thresholds for 4 hours following morphine administration, compared with baseline values; individually, thresholds decreased to baseline values within (mean +/- SE) 2.8 +/- 0.6 hours. The maximal effect (change from baseline values) was 213 +/- 43%, and the plasma morphine concentration to achieve 50% maximal effect was 13.92 +/- 2.39 ng/mL. CONCLUSIONS AND CLINICAL RELEVANCE: Data suggest that, in dogs, evaluation of the antinociceptive effect and pharmacodynamic modeling of a dose of morphine sulfate (1 mg/kg, i.v.) can be successfully achieved by use of a von Frey device.

Comparison of the standard predictive equation for calculation of resting energy expenditure with indirect calorimetry in hospitalized and healthy dogs.

OBJECTIVE: To determine the level of clinical agreement between 2 methods for the measurement of resting energy expenditure (REE). DESIGN: Prospective case series. ANIMALS: 77 dogs. PROCEDURE: Oxygen consumption (Vo2) and CO2 production (Vco2) were measured with an open-flow indirect calorimeter in healthy (n = 10) and ill (67) dogs. Measurements were collected at 3 time periods on 2 days. The Vo2 and the Vco2 measurements were then used to calculate the REE values. RESULTS: Mean values of measured (MREE) and predicted (PREE) REEs in healthy dogs and a dog with medical illnesses or trauma were not significantly different. There was a significant difference on day 2 between the MREE and PREE in the group of dogs recovering from major surgery. More importantly, there was significant variation between the PREE and MREE on an individual-dog basis. The PREE only agreed to within +/- 20% of the MREE in 51% to 57% of the dogs. CONCLUSIONS AND CLINICAL RELEVANCE: The level of agreement between these two methods for determining the 24-hour REE was poor in individual dogs. The level of disagreement between the 2 methods indicates that these methods may not be used interchangeably in a clinical setting. Measurement of REE by use of indirect calorimetry may be the only reliable method of determining REE in an individual ill or healthy dog.