Basic science knowledge underlies clinical science knowledge and clinical problem solving: evidence from veterinary medicine.

Medical sciences education emphasizes basic science learning as a prerequisite to clinical learning. Studies exploring relationships between achievement in the basic sciences and subsequent achievement in the clinical sciences generally suggest a significant positive relationship. Basic science knowledge and clinical experience are theorized to combine to form encapsulated knowledge- a dynamic mix of information that is useful for solving clinical problems. This study explores the relationship between basic science knowledge (BSK), clinical science knowledge (CSK), and clinical problem-solving ability, as measured within the context of four veterinary colleges using both college-specific measures and professionally validated, standardized measures of basic and clinical science knowledge and problem-solving ability. Significant correlations existed among all variables. Structural equation modeling and confirmatory factor analysis were used to produce models showing that newly acquired BSK directly and significantly predicted BSK retained over time and newly acquired CSK, as well as indirectly predicted clinical problem-solving ability (mediated by newly acquired CSK and BSK retained over time). These findings likely suggest a gradual development of schema (encapsulated knowledge) and not an isolated development of biomedical versus clinical knowledge over time. A broader implication of these results is that explicitly teaching basic science knowledge positively and durably affects subsequent clinical knowledge and problem-solving ability independent of instructional strategy or curricular approach. Furthermore, for veterinary colleges specifically, student performance as measured by both course-level and standardized tests are likely to prove useful for predicting subsequent academic achievement in classroom and clinical settings, licensing examination performance, and/or for identifying students likely in need of remediation in clinical knowledge.

Impact of fatty acid composition on markers of exocrine pancreatic stimulation in dogs.

Chronic pancreatitis in dogs is typically managed with a low-fat diet. Human research suggests that consumption of medium-chain triglycerides (MCT) may lessen pancreatic enzyme release compared to consumption of long-chain fatty acids (LCFA). Twelve healthy adult colony dogs were fed a meal of cod and rice with either 3% metabolizable energy (ME) fat (control), high MCT (25% ME MCT oil, 25% ME butter), high saturated LCFA (50% ME butter), or high unsaturated LCFA (50% ME canola oil) in a 4-period by 4-treatment crossover design. Serum concentrations of canine pancreatic lipase immunoreactivity, gastrin, cholesterol, triglycerides, and serum activities of amylase and DGGR lipase (1,2-o-dilauryl-rac-glycero-3-glutaric acid-(69-methylresorufin) ester lipase) were measured at times 0 (fasted), 30, 120 and 180 minutes post-prandially. Following a 3-or 4-day wash-out period, each dog was assigned a new diet and the process was repeated for all treatments. Data were analyzed as a repeated-measures mixed model ANOVA. Post-hoc pairwise comparisons were run using Tukey-Kramer adjusted p-values. Shapiro-Wilk tests were used to evaluate residual normality. All statistical assumptions were sufficiently met. Statistical significance was defined as P<0.05. Of the markers tested, only serum triglyceride concentrations were affected by treatment, with consumption of high MCT resulting in lower triglycerides than both LCFA groups at times 120 and 180 minutes (P<0.0001). As expected, the high MCT group had higher triglycerides compared to the control group (P<0.0001). The type of dietary fat consumed had little acute impact on most markers of exocrine pancreatic stimulation in healthy dogs.

Effect of a Leucine/Pyridoxine Nutraceutical on Caloric Intake and Body Composition of Obese Dogs Losing Weight.

The aim of this 29-week randomized, positively and negatively controlled study was to investigate whether a nutraceutical containing 1 g leucine and 13 mg pyridoxine can enhance weight loss while maintaining lean muscle mass in obese dogs. Twenty-four healthy, 2-year-old beagles were initially divided into obesification (n = 18) or ideal body weight groups (n = 6). After obesification, the 18 dogs were divided into three weight loss groups and fed one of the following over 12 weeks: nutraceutical with canned adult diet (CAD; ObN), placebo with CAD (ObP), or a canned therapeutic weight loss diet (WLD). Dogs in the ideal body weight (IBW) group were fed maintenance calorie requirements with CAD over 12 weeks. Based on MANOVA, ObN and WLD lost similar amounts of total weight (3.6 ± 0.9 vs. 4.4 ± 1.1 kg, respectively) and fat mass (3.1 ± 0.6 vs. 3.9 ± 0.8 kg, respectively) after 12 weeks of treatment, and more than ObP (1.1 ± 1.2 kg weight; 0.9 ± 1.0 kg fat; p < 0.0001). These data show the nutraceutical is a promising option for successful weight loss in dogs. Maintenance levels of CAD were able to induce weight loss without risk of hypo- or anorexia, or the need to switch diets or restrict energy intake.

Body composition of lean outdoor intact cats vs lean indoor neutered cats using dual-energy x-ray absorptiometry.

OBJECTIVES: The objectives for this study were to compare the body composition of adult indoor neutered domestic cats with outdoor intact cats with an ideal body condition score using dual-energy x-ray absorptiometry, and to report the body composition findings of free-roaming cats, as this has not been previously reported. Most domestic house cats differ from free-roaming cats as they are confined indoors and neutered. Indoor neutered cats have reduced activity and hormonal alterations that may result in lower muscle mass and higher body fat percentages vs outdoor intact cats, despite similar body condition scores. METHODS: Twenty-one outdoor intact cats (10 male, 11 female) were selected from a trap-neuter-return program and 16 indoor neutered domestic cats (10 male, six female) were client-owned. Inclusion criteria included an estimated age between 1 and 6 years, complete blood count, biochemistry panel, urinalysis, total thyroxine, feline leukemia virus/feline immunodeficiency virus screening and a body condition score of 4-5/9. RESULTS: Indoor neutered cats had a higher body fat percentage (22.1% [range 17.3-28.2%]) than outdoor intact cats (17.3% [range 10.0-33.6%]; P = 0.002). Indoor neutered male cats had a higher body fat percentage ( P <0.001) than outdoor intact cats. No difference in body fat percentage was observed in female cats ( P = 0.159). Indoor neutered domestic cats had a higher bone mineral density than outdoor intact cats ( P = 0.023). CONCLUSIONS AND RELEVANCE: The results of this study suggest indoor confinement and neutering increase body fat percentage and bone mineral density in cats with an ideal body condition score.

Evaluation of two raw diets vs a commercial cooked diet on feline growth.

Objectives The objective of this study was to determine if two raw feline diets were nutritionally adequate for kittens. Methods Twenty-four 9-week-old kittens underwent an Association of American Feed Control Officials' (AAFCO) 10 week growth feeding trial with two raw diet groups and one cooked diet group (eight kittens in each). Morphometric measurements (weight, height and length), complete blood counts, serum chemistry, whole blood taurine and fecal cultures were evaluated. Results Overall, the growth parameters were similar for all diet groups, indicating the two raw diets used in this study supported feline growth, within the limitations of an AAFCO growth feeding trial. Kittens fed the raw diets had lower albumin ( P = 0.010) and higher globulin ( P = 0.04) levels than the kittens fed the cooked diet. These lower albumin levels were not clinically significant, as all groups were still within normal age reference intervals. A red cell microcytosis ( P = 0.001) was noted in the combination raw diet group. Increases in fecal Clostridium perfringens were noted in all groups, along with positive fecal Salmonella serovar Heidelberg and Clostridium difficile toxin in the combination raw diet group. Conclusions and relevance The majority of the parameters for feline growth were similar among all groups, indicating the two raw diets studied passed an AAFCO growth trial. In theory, it is possible to pass an AAFCO growth trial but still have nutrient deficiencies in the long term due to liver and fat storage depots. Some of the raw feeders had elevated globulin and microcytosis, likely associated with known enteropathogenic exposure. Disease risks to both pets and owners are obvious. Additional research in this area is needed to investigate the impact of raw diets on the health of domestic cats.

Prevalence of asymptomatic urinary tract infections in morbidly obese dogs.

Background. Obesity has reached epidemic proportions in dogs and, as in humans, cost of care has increased due to associated comorbidities. In humans, asymptomatic urinary tract infections (UTI) may be more prevalent in the obese. Asymptomatic bacteriuria (AB) is the term used when UTI are asymptomatic. We hypothesized that morbidly obese dogs are similarly more likely to have asymptomatic bacteriuria than lean, overweight, and moderately obese dogs. Methods. A retrospective study was undertaken to explore a possible association between obesity and asymptomatic bacteriuria. Records from lean, overweight, and obese dogs receiving both a dual energy absorptiometry (DXA) scan and urine culture were included. Results. Six positive urine cultures were identified among 46 dogs fulfilling search criteria. All six positive cultures were found in dogs with body fat percentage of >45%. In dogs with body fat percentage of <45%, there were no positive urine cultures. Discussion. There was an increased prevalence of asymptomatic bacteriuria in the morbidly obese dogs in this study compared to those that were lean, overweight, or moderately obese. Whether antibiotic therapy is necessary in such cases is still being debated, but because asymptomatic bacteriuria may be associated with ascending infections, uroliths, or other complications, the data reported herein support the screening of obese patients for bacteriuria.

Apparent nutrient digestibility of two raw diets in domestic kittens.

OBJECTIVES: The aim of the study was to evaluate overall dry matter, organic matter, crude protein, crude fat and gross energy digestibility of a feline commercial raw diet and a homemade raw diet compared with a canned, heat-processed diet. METHODS: Six domestic shorthair kittens (20-28 weeks old) were fed three different diets in a Latin square crossover design. Diet A was a commercially available, canned, heat-processed diet. Diet B was a complete commercial, prefrozen, raw diet (commercial raw), and diet C was a raw diet supplement mixed with ground raw meat obtained locally (homemade raw). Both diets A and B were formulated to meet nutritional profile levels for cats at all life stages. Kittens were given specific diet amounts to maintain a 2-4% weight increase per week. Food was measured before and after feedings to determine the amount eaten, and all feces were collected, weighed and frozen prior to submission. Composite food samples and all feces were submitted to a national laboratory for proximate analysis of crude protein, crude fiber, ash, crude fat, moisture and caloric density. RESULTS: Significantly higher digestibility of dry matter (P <0.001), organic matter (P <0.001), crude protein (P <0.001) and gross energy (P <0.001) was seen in the raw diets compared with the heat-processed diets. This difference resulted in significantly less fecal matter (P <0.001) despite similar levels of intake and kcal ingested, and evidence of no difference in fecal scores. CONCLUSIONS AND RELEVANCE: Higher dry matter, organic matter and protein digestibility was seen in two commercial raw diets compared with a heat-processed diet. Digestibility differences could have been due to variance in dietary protein, fat and carbohydrate concentrations between the diets, variance in dietary ingredients or quality, alterations in protein structure secondary to heat processing, as well as alterations in gastrointestinal flora. Future research examining digestibility in diets with the same macronutrient proportions and ingredients, and mechanisms for any differences, is warranted.

Use of a novel morphometric method and body fat index system for estimation of body composition in overweight and obese dogs.

OBJECTIVE: To develop morphometric equations for prediction of body composition and create a body fat index (BFI) to estimate body fat percentage in overweight and obese dogs. DESIGN: Prospective evaluation study. ANIMALS: 83 overweight or obese dogs ≥ 1 year of age. PROCEDURES: Body condition score (BCS) was assessed on a 5-point scale, morphometric measurements were made, and visual and palpation-based assessments and dual-energy x-ray absorptiometry (DEXA) were performed. Equations for predicting lean body mass, fat mass, and body fat as a percentage of total body weight (ie, body fat percentage) on the basis of morphometric measurements were generated with best-fit statistical models. Visual and palpation-based descriptors were used to develop a BFI. Predicted values for body composition components were compared with DEXA-measured values. RESULTS: For the study population, the developed morphometric equations accounted for 98% of the variation in lean body mass and fat mass and 82% of the variation in body fat percentage. The proportion of dogs with predicted values within 10% of the DEXA values was 66 of 83 (80%) for lean body mass, 56 of 83 (68%) for fat mass, and 56 of 83 (67%) for body fat percentage. The BFI accurately predicted body fat percentage in 25 of 47 (53%) dogs, whereas the value predicted with BCS was accurate in 6 of 47 (13%) dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Morphometric measurements and the BFI appeared to be more accurate than the 5-point BCS method for estimation of body fat percentage in overweight and obese dogs. Further research is needed to assess the applicability of these findings to other populations of dogs.

Use of a morphometric method and body fat index system for estimation of body composition in overweight and obese cats.

OBJECTIVE: To develop morphometric equations for prediction of body composition and create a body fat index (BFI) system to estimate body fat percentage in overweight and obese cats. DESIGN: Prospective evaluation study. ANIMALS: 76 overweight or obese cats ≥ 1 year of age. PROCEDURES: Body condition score (BCS) was determined with a 5-point scale, morphometric measurements were made, and dual-energy x-ray absorptiometry (DEXA) was performed. Visual and palpation-based evaluation of various body regions was conducted, and results were used for development of the BFI system. Best-fit multiple regression models were used to develop equations for predicting lean body mass and fat mass from morphometric measurements. Predicted values for body composition components were compared with DEXA results. RESULTS: For the study population, prediction equations accounted for 85% of the variation in lean body mass and 98% of the variation in fat mass. Values derived from morphometric equations for fat mass and lean mass were within 10% of DEXA values for 55 of 76 (72%) and 66 of 76 (87%) cats, respectively. Body fat as a percentage of total body weight (ie, body fat percentage) predicted with the BCS and BFI was within 10% of the DEXA value for 5 of 39 (13%) and 22 of 39 (56%) cats, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The BFI system and morphometric equations were considered accurate for estimation of body composition components in overweight and obese cats of the study population and appeared to be more useful than BCS for evaluation of these patients. Further research is needed to validate the use of these methods in other feline populations.

Influence of acidifying or alkalinizing diets on bone mineral density and urine relative supersaturation with calcium oxalate and struvite in healthy cats.

OBJECTIVE: To evaluate the influence of acidifying or alkalinizing diets on bone mineral density and urine relative supersaturation (URSS) with calcium oxalate and struvite in healthy cats. ANIMALS: 6 castrated male and 6 spayed female cats. PROCEDURES: 3 groups of 4 cats each were fed diets for 12 months that differed only in acidifying or alkalinizing properties (alkalinizing, neutral, and acidifying). Body composition was estimated by use of dual energy x-ray absorptiometry, and 48-hour urine samples were collected for URSS determination. RESULTS: Urine pH differed significantly among diet groups, with the lowest urine pH values in the acidifying diet group and the highest values in the alkalinizing diet group. Differences were not observed in other variables except urinary ammonia excretion, which was significantly higher in the neutral diet group. Calcium oxalate URSS was highest in the acidifying diet group and lowest in the alkalinizing diet group; struvite URSS was not different among groups. Diet was not significantly associated with bone mineral content or density. CONCLUSIONS AND CLINICAL RELEVANCE: Urinary undersaturation with calcium oxalate was achieved by inducing alkaluria. Feeding an alkalinizing diet was not associated with URSS with struvite. Bone mineral density and calcium content were not adversely affected by diet; therefore, release of calcium from bone caused by feeding an acidifying diet may not occur in healthy cats.

Comparison of a human portable blood glucose meter, veterinary portable blood glucose meter, and automated chemistry analyzer for measurement of blood glucose concentrations in dogs.

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.

Changes in hepatic gene expression in dogs with experimentally induced nutritional iron deficiency.

BACKGROUND AND OBJECTIVE: We investigated hepatic gene expression in dogs with experimentally induced nutritional iron deficiency (ID). Our hypothesis was that ID would result in decreased hepcidin gene expression, and possibly in altered expression of other genes associated with iron metabolism. METHODS: Liver biopsies were collected from each of 3 dogs before induction of ID, at the point of maximal ID, and after resolution of ID. Using Affymetrix microarray technology and analytical tools specifically designed for microarray data, we identified genes that had at least a 2-fold change in expression in response to ID. Four genes were selected for further analysis by reverse transcriptase PCR (RT-PCR). RESULTS: Dogs with ID had markedly decreased expression of the hepcidin gene (mean decrease of 40-fold for one probe and >100-fold for another probe) and increased expression of the transferrin receptor gene (mean increase of >7-fold). There was also mildly decreased expression of the "similar to calreticulin" gene and a gene of unknown function. Results of RT-PCR analysis were consistent with microarray findings. CONCLUSION: Changes in hepcidin and transferrin receptor gene expression were consistent with the known biology of iron metabolism. The decrease in expression of a gene identified as "similar to calreticulin," while not statistically significant, was consistent with the findings of other investigators that suggest iron plays a role in calreticulin expression.

Aflatoxicosis in nine dogs after exposure to contaminated commercial dog food.

The purpose of this study was to characterize light and electron microscopic findings from 9 dogs that had consumed aflatoxin-contaminated commercial dog food from recalled batches. Four dogs died and 5 were euthanized after signs of liver failure. Analysis of feed and liver samples confirmed exposure to aflatoxin. Of the 9 dogs, 8 had classic signs of liver failure, and 1 had signs of liver failure. Enlarged, pale yellow livers were seen macroscopically at necropsy in the dogs with subacute hepatopathy, and cirrhosis was noted in the dog with chronic hepatopathy. Histopathologic findings included hepatic lipidosis, portal fibroplasia, and biliary hyperplasia, which supported a diagnosis of subacute toxic hepatopathy in the 8 symptomatic animals. Marked lobular atrophy, bridging portal fibrosis, and regenerative hepatocellular nodules characterized the dog with chronic hepatopathy. Electron microscopy revealed marked hepatocellular lipid vacuolation and early fibroplasia in the dogs with acute hepatopathy and marked fibrosis and regeneration in the dog with chronic hepatopathy. Analysis of feed for aflatoxin consistently revealed high levels of aflatoxin B1 (range of 223-579 ppb), and hepatic tissue contained elevated levels of aflatoxin B1 metabolite M1 (0.6-4.4 ppb). Although dogs are not commonly affected by aflatoxicosis, they are highly susceptible and can present with classic signs of acute or chronic hepatopathy. Characteristic gross, histologic, and electron microscopic changes help pathologists determine a presumptive toxic insult. Detecting aflatoxins or their metabolites in feed or liver specimens can help confirm the diagnosis of aflatoxicosis.

Influence of prednisolone on urinary calcium oxalate and struvite relative supersaturation in healthy young adult female domestic shorthaired cats.

Prednisolone (10 mg PO q24h) or placebo was administered to healthy cats for 2 weeks in a masked, placebo-controlled, crossover-design study, and 24-hour urine samples were collected. When cats received prednisolone, 24-hour urine pH was lower and 24-hour urine excretion of creatinine, magnesium, phosphate, and potassium was higher than when cats received placebo. No significant difference was found in urinary relative supersaturation for calcium oxalate (CaOx) or struvite between treatment groups. Prednisolone administration did not induce diuresis, nor was it associated with increased calcium excretion or urinary saturation for CaOx in these healthy cats. Results of this study, however, should not be extrapolated to cats that form CaOx uroliths associated with idiopathic hypercalcemia.

Influence of hydrochlorothiazide on urinary calcium oxalate relative supersaturation in healthy young adult female domestic shorthaired cats.

Hydrochlorothiazide (1 mg/kg PO q12h) or placebo was administered to healthy cats for 2 weeks in a masked, placebo-controlled, crossover-design study, and 24-hour urine samples were collected. When cats received hydrochlorothiazide, 24-hour urine volume, ammonia, chloride, creatinine, magnesium, oxalic acid, phosphate, potassium, and sodium were significantly higher than when cats received placebo. Hydrochlorothiazide was associated with significantly lower urinary saturation for calcium oxalate, but no difference was found in 24-hour urine calcium and citrate, urinary saturation for struvite, or blood ionized calcium. Hydrochlorothiazide decreased urinary saturation for calcium oxalate and could be useful in managing cats with calcium oxalate uroliths. Results of this study, however, should not be extrapolated to cats that form calcium oxalate uroliths.

Feline diabetes mellitus: low carbohydrates versus high fiber?

Treatment of diabetes mellitus (DM) in the cat relies primarily on the adequate insulin therapy and controlled dietary intake. The goals of managing DM in the cat have changed from attaining glycemic control to achieving diabetic remission (transient diabetes) in a large proportion of cases. Remission rates of up to 68% have been published. The used of low-carbohydrate foods for cats improves the odds of achieving diabetic remission by fourfold. Nonetheless, some cats show an improved response to high-fiber food. Clinical judgement, trial, and personal preference to currently dictate which diet to offer an individual animal.

Nutrition and lower urinary tract disease in cats.

Lower urinary tract disease occurs commonly in cats and is often associated with crystal-related disease. Dietary modification is beneficial in managing some of these diseases, including idiopathic cystitis, urolithiasis, and urethral matrix-crystalline plugs. Altering dietary formulation may result in decreasing urinary concentrations of crystallogenic compounds, increasing urinary concentrations fo crystallogenic inhibitors, and diluting urine composition.

Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats.

Objective-To determine whether a renal diet modified in protein, phosphorus, sodium, and lipid content was superior to an adult maintenance diet in minimizing uremic episodes and mortality rate in cats with stage 2 or 3 chronic kidney disease (CKD). Design-Double-masked, randomized, controlled clinical trial. Animals-45 client-owned cats with spontaneous stage 2 or 3 CKD. Procedures-Cats were randomly assigned to an adult maintenance diet (n = 23 cats) or a renal diet (22) and evaluated trimonthly for up to 24 months. Efficacy of the renal diet, compared with the maintenance diet, in minimizing uremia, renal-related deaths, and all causes of death was evaluated. Results-Serum urea nitrogen concentrations were significantly lower and blood bicarbonate concentrations were significantly higher in the renal diet group at baseline and during the 12- and 24-month intervals. Significant differences were not detected in body weight; Hct; urine protein-to-creatinine ratio; and serum creatinine, potassium, calcium, and parathyroid hormone concentrations. A significantly greater percentage of cats fed the maintenance diet had uremic episodes (26%), compared with cats fed the renal diet (0%). A significant reduction in renal-related deaths but not all causes of death was detected in cats fed the renal diet. Conclusions and Clinical Relevance-The renal diet evaluated in this study was superior to an adult maintenance diet in minimizing uremic episodes and renalrelated deaths in cats with spontaneous stage 2 or 3 CKD.