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Background: Plasma total magnesium concentration (tMg) is a prognostic indicator in cats with chronic kidney disease (CKD), shorter survival time being associated with hypomagnesemia. Whether this risk factor is modifiable with dietary magnesium supplementation remains unexplored. Objectives: Evaluate effects of a magnesium‐enriched phosphate‐restricted diet (PRD) on CKD–mineral bone disorder (CKD‐MBD) variables. Animals: Sixty euthyroid client‐owned cats with azotemic CKD, with 27 and 33 allocated to magnesium‐enriched PRD or control PRD, respectively. Methods: Prospective double‐blind, parallel‐group randomized trial. Cats with CKD, stabilized on a PRD, without hypermagnesemia (tMg >2.43 mg/dL) or hypercalcemia (plasma ionized calcium concentration, (iCa) >6 mg/dL), were recruited. Both intention‐to‐treat and per‐protocol (eating ≥50% of study diet) analyses were performed; effects of dietary magnesium supplementation on clinicopathological variables were evaluated using linear mixed effects models. Results: In the per‐protocol analysis, tMg increased in cats consuming a magnesium‐enriched PRD (β, 0.25 ±.07 mg/dL/month; P <.001). Five magnesium supplemented cats had tMg >2.92 mg/dL, but none experienced adverse effects. Rate of change in iCa differed between groups (P =.01), with decreasing and increasing trends observed in cats fed magnesium‐enriched PRD and control PRD, respectively. Four control cats developed ionized hypercalcemia versus none in the magnesium supplemented group. Log‐transformed plasma fibroblast growth factor‐23 concentration (FGF23) increased significantly in controls (β, 0.14 ±.05 pg/mL/month; P =.01), but remained stable in the magnesium supplemented group (β, 0.05±.06 pg/mL/month; P =.37). Conclusions and Clinical Importance: Magnesium‐enriched PRD is a novel therapeutic strategy for managing feline CKD‐MBD in cats, further stabilizing plasma FGF23 and preventing hypercalcemia. [ABSTRACT FROM AUTHOR]

BackgroundUrate urolithiasis is a common problem in breed homozygous for the mutation that results in hyperuricosuria. Low purine diets have been recommended to reduce purine intake in these dogs.MethodsA higher protein, purine restricted diet with water added was evaluated in dogs with genetic hyperuricosuria and a history of clinical urate urolithiasis over a one year time period. Dogs were evaluated at baseline and 2, 6, and 12 months after initiating the test diet. Bloodwork, urinalysis, abdominal ultrasound, body composition, and 24-h urinary purine metabolite analyses were performed.ResultsTransient, mild, self-limited lower urinary tract signs were noted in only one dog on a single day, despite variable but usually mild and occasionally moderate amounts of echogenic bladder stones (

Background: High‐salt diets promote urine dilution and decrease urolithiasis risk. Objective: Prospectively evaluate the safety of chronic high dietary salt intake (randomized controlled trial). Animals: Twenty research colony neutered, healthy aged cats (11.5 years [10.0‐11.6], median [interquartile range]). Methods: Healthy cats were randomized to control or high‐salt dry diets (sodium: 1.02 ± 0.16 [mean, SD] and 3.26 ± 0.30 g/Mcal metabolizable energy [ME], respectively; chloride: 2.26 ± 0.33 and 5.71 ± 0.28 g/Mcal ME, respectively), fed for up to 60 months. Assessments included CBC, plasma biochemistry, urinalysis, glomerular filtration rate (GFR), blood pressure, renal and cardiac (conventional Doppler and 2‐dimensional color tissue Doppler) imaging, annually. Cats that died or were euthanized underwent necropsy. Diet effects over time were evaluated with linear mixed models. Results: Follow‐up duration (median [Interquartile range]) was similar between the control (38.7 months [28.6‐48.2]) and high‐salt group (51.4 months [45.7‐59.0]). Diet had no significant effect on changes in GFR, blood pressure, plasma creatinine concentration, end‐diastolic left ventricular (LV) wall thicknesses, LV internal diameters, LV systolic function, left atrial size, or systolic and diastolic Doppler variables. One control cat developed hypertension. One high‐salt group cat developed persistent azotemia. Serial plasma biochemistry and urine specific gravity suggested early chronic kidney disease in 4 nonazotemic cats (2 per group), consistent with necropsy findings. Conclusions and Clinical Importance: In healthy aged cats, a commercial veterinary diet containing 3.26 ± 0.30 g/Mcal ME sodium was safe with regard to renal and cardiac function for up to 5 years. [ABSTRACT FROM AUTHOR]

Background: The veterinary care of cats and dogs is increasingly embracing innovations first applied to human health, including an increased emphasis on preventative care and precision medicine. Large scale human population biobanks have advanced research in these areas; however, few have been established in veterinary medicine. The MARS PETCARE BIOBANK™ (MPB) is a prospective study that aims to build a longitudinal bank of biological samples, with paired medical and lifestyle data, from 20,000 initially healthy cats and dogs (10,000 / species), recruited through veterinary hospitals over a ten-year period. Here, we describe the MPB protocol and discuss its potential as a platform to increase understanding of why and how diseases develop and how to advance personalised veterinary healthcare. Methods: At regular intervals, extensive diet, health and lifestyle information, electronic medical records, clinicopathology and activity data are collected, genotypes, whole genome sequences and faecal metagenomes analysed, and blood, plasma, serum, and faecal samples stored for future research. Discussion: Proposed areas for research include the early detection and progression of age-related disease, risk factors for common conditions, the influence of the microbiome on health and disease and, through genome wide association studies, the identification of candidate loci for disease associated genetic variants. Genomic data will be open access and research proposals for access to data and samples will be considered. Over the coming years, the MPB will provide the longitudinal data and systematically collected biological samples required to generate important insights into companion animal health, identifying biomarkers of disease, supporting earlier identification of risk, and enabling individually tailored interventions to manage disease. [ABSTRACT FROM AUTHOR]

Breath hydrogen (H[sub.2]) concentration, an indicator of intestinal microbial abundance, was determined in cats given purified and commercial canned and dry-type diets. Before measurements, the cats were fed diets for more than 2 wk and habituated to a daily feeding interval of 4 hr. Breath H[sub.2] concentrations were determined before a meal (~25% daily MER) and then every 20 min for 8 hr or hourly for 10 hr. A clear rise above baseline breath H[sub.2] concentrations, 1-2 ppm, was not observed in 6 males given a casein-based purified diet. A mean ([+ or -]SEM) peak breath H[sub.2] concentration of 22[+ or -]4 ppm was observed in 6 other males, 6.3 hr after ingestion of a canned diet with protein, fat, and carbohydrate proportions similar to those of the purified diet. Area-under-the-curve (AUC) breath H[sub.2] responses to the canned diet were substantially greater (p < 0.05) than responses observed in 5 males given a dry-type diet, but similar to responses observed in 12 males given an uncooked form of the canned diet. Gamma irradiation to inactivate microbes in the uncooked diet did not affect the breath H[sub.2] response. Breath H[sub.2] responses to 2 other canned and 2 other dry-type diets were evaluated in 8 adult females using a 4 x 4 Latin-square design. Peak and AUC responses to the canned diets were similar but approximately 2 times greater (p < 0.05) than responses to the dry diets. Relative to dry-type diets, canned diets induce a substantially greater breath H[sub.2] production, and therefore appear to support a greater intestinal microbial population. KEY WORDS: * domestic cats * breath hydrogen concentration * gastrointestinal microflora * food bacteria * oral-cecal transit time

Great variations in the postprandial glucose concentration and insulin secretory responses to different foods have been shown in dogs (Holste and al. 1989, Nguyen and al. 1994). It has been suggested that foods yielding low glycemic responses would be recommended for diabetic or obese subjects and in the prevention of many other disorders. High carbohydrate/high fiber diets enhance peripheral glucose disposal and decrease insulin requirements in insulin-dependent diabetic subjects. In overweight patients with noninsulin-dependent diabetes mellitus (NIDDM), reducing diet glycemic response improves overall blood glucose control, long-term glycemic control and lipid control. Diets with a high glycemic response that are low in fiber increase the risk of NIDDM in humans. Foods with a low glycemic response combined with a high dietary fiber content decrease free fatty acid level, which is associated with abdominal obesity and cardiovascular risk. They cause rapid intestinal absorption of glucose into the blood, leading to postprandial hyperinsulinemia, which may play a role in promoting colon carcinogenesis. A diet high in refined carbohydrates and low in water-soluble fiber causes rapid absorption of glucose with similar results. Because of the clinical implications of the glycemic index, notably in diabetes management or in dietary strategy to avoid or treat overweight or moderate obesity, the factors that affect it have been the subject of many studies (Wolever and al. 1991). The extent of postprandial hyperglycemia and insulin secretion depends on the amount of food and carbohydrate consumed per meal. However, different kinds of carbohydrate elicit different glucose and insulin concentrations, because their chemical nature, especially the ratio of amylose to amylopectin forms of starch, may affect their rate and speed of digestion. Dietary fiber slows down the rate of passage and the rate of hydrolysis of starchy polysaccharides (Wolever 1990). Dietary fat delays stomach emptying (Gulliford and al. 1989), and high intakes of rapidly digested proteins modify the glycemic response by increasing insulin secretion (Nuttall and Gannon 1990). The food processing may be of particular importance for dog food. The type of food, dry, canned or soft moist, affects the maximal postprandial glucose concentration as much as the time at which this peak occurs (Holste and al. 1989). The glycemic index methodology is based on tests of single foods and could be applied to the testing of mixed meals. Nevertheless, its practical utility is controversial because differences among foods could be partially abolished in mixed meals by the effects of protein and fat. Whatever it may be, an individual food evaluation is not realistic in dogs. Their complete foods contain many components. There are large variations in their protein and fat content and the technological processes can largely modify the intrinsic carbohydrate availability. Nevertheless, information concerning postprandial responses would be of great interest in regard to obesity. Along with a long-term excessive energy intake, food quality may play a significant role according to its humoral and metabolic effects. This information may also be of interest in the management of NIDDM (which elicits alteration of carbohydrate tolerance and insulin action) as much as insulin-dependent diabetes mellitus (IDDM; reduction of fluctuations in blood glucose, synchronization of glucose increase and insulin administration). The purpose of this study was to determine how the differences in carbohydrate (starch and dietary fiber, soluble and insoluble), protein and fat content of complete (and complex) foods given to healthy dogs in a single meal on a normoenergetic basis modify their postprandial plasma glucose and insulin responses. Material and methods. Animals. Twelve adult (older than 15 mo) beagle dogs were studied, according to the French Ministry of Agriculture and Fisheries regulatory rules for animal welfare. They were allotted to two groups; from each group, five dogs were used alternately for tests, excluding in particular dogs that did not eat the entire meal that they were offered. None of the dogs was obese (13.5 kg mean body weight) and they were clinically normal. Their basal plasma glucose (5.21 [+ or -] 0.50 mmol/L) and their response to the intravenous glucose tolerance test (performed after a 24-h period of food deprivation, using a glucose dose of 500 mg/kg body weight, infused as 50% glucose solution in 30 s) were also normal. These dogs were accustomed to the experimental procedure. They were commonly used for digestibility trials in the cages used in this study and had been previously subjected to repeated venipuncture. Therefore, their responses were due to the experimental variables and not to stress. Experimental diets. Twenty experimental foods (C1-C5 and D1-D15) were tested. Foods D1-D15 were dry foods, whereas C1-C5 were canned. These test foods were intended to be representative of foods currently used for maintenance or for clinical purposes in adult dogs. They were designed to vary in macronutrient composition [15.4-62.6% crude protein (CP), 7.9-31.0% ether extract (EE), 3.2-39.1% total dietary fiber (TDF) and 0.4-52.7% starch (ST), on a dry matter basis]; the energy content was 965-2045 kJ/100 g dry matter. The composition of test meals is shown in Table 1. The daily chromium intake was not KEY WORDS: * dog foods * analytical composition * food processing * glycemic response * insulinemic response * dogs

Variations in the blood glucose and insulin responses to different foods have been studied in dogs (Holste et al. 1989, Nguyen et al. 1994), and different trends in postprandial concentrations have been observed. These differences arose in the extent of the variations (areas under the curves and maximal increments) and the time from meal to peak increases. The main purpose of these studies was to rank foods on the basis of the incremental glucose responses that they produced and to relate these responses to foods characteristics. It is known that methodologic variables can markedly modify the interpretation of the glycemic response. In particular, this concerns the length of time of blood sampling (Gannon and Nuttall 1987), short-term (Wolever and al. 1988) and long-term (Cannon and al. 1980) remnant effects of the previous meal, blood sampling (Jackson and al. 1983) and fasting blood glucose values (Nielsen and Nielsen 1989). In dogs, the variations of the glycemic response have been evaluated with (Holste et al. 1989) or without (Nguyen et al. 1994) an adaptation period to the tested meals. As in human beings, the plasma concentrations were measured over a period of 3 or 4 h even though the gastrointestinal transit time is shorter in dogs than in humans. The purpose of our study was to examine whether an adaptation time (inducing digestive changes and modifications in basal insulin secretion and glucose tolerance) modifies the postprandial response to meal feeding in normal dogs. We also studied the effect of length of time of blood sampling on the consistency of the response value expressed by the areas under the glycemic and insulin curves, the peak incremental values and the times from meal to peaks. Materials and methods. Animals. Twelve adult (older than 15 mo) beagle dogs, allotted to two groups, were studied, according to the French Ministry of Agriculture and Fisheries regulatory rules for animal welfare. None of the dogs was obese (13.7 kg mean body weight) and all were clinically normal. Their basal plasma glucose (Experiment 1:5.41 [+ or -] 0.54 mmol/L; Experiment 2:5.27 [+ or -] 0.55 mmol/L) and their response to the intravenous glucose tolerance test (performed after a 24-h period of food deprivation), using a glucose dose of 500 mg/kg body weight, infused as 50% glucose solution in 30 s, were also normal. These dogs were accustomed to the experimental procedure. They were commonly used for digestibility trials in the cages used in this study and had been previously subjected to repeated venipuncture. Therefore, their responses were due to the experimental variables and not to stress. Experimental diets. Two experiments were performed according to the two objectives. Experiment 1. Five experimental foods (A1, A2 and B1-B3 foods) were tested. Foods A1 and A2 were canned foods, whereas B1-B3 were dry. Foods B1 and B3 were given as is, with separate water, whereas food B2 was hydrated before feeding. These test foods were intended to be representative of foods currently used for maintenance in adult dogs. They were designed to vary in macronutrient composition [27.2-62.6% crude protein (CP), 10.9-25.7% ether extract (EE), 1.1-3.6% crude fiber (CF), 4.4-50.5% nitrogen-free extract (NFE) and 3.2-12.4% total dietary fiber (TDF), on a dry matter basis]. The energy profile was as follows: 25-54% energy derived from protein, 25-51% from fat and 4-48% from nitrogen-free extract, according to standard energy conversion factors, 14.6 kJ/g CP or NFE, 35.6 kJ/g EE). The composition of the test meals is shown in Table 1. The daily chromium intake was not 90 min appears to be unnecessary to characterize the glycemic and insulin responses to meals in normal dogs. The effects of the length of time of blood sampling on the relative area under the glucose curve of foods in humans has been reviewed (Gannon and Nuttall 1987). Long-time measurements tend to reduce the differences in AUCG between foods, especially between foods resulting in high peak rises followed by a rapid decrease, and foods for which the glucose response presents a lower peak but tends to remain above the baseline for a prolonged period of time. If measured for too long a time, the area under these types of curves may be nearly the same, despite markedly different effects on insulin and counterregulatory hormone responses. These factors are related to the acute rate of carbohydrate absorption, which in turn is related to the incremental area under the early part (120 min) of the glucose response curve in normal subjects (Wolever et al. 1991). A shorter duration of blood sampling could be sufficient in normal dogs because of their high gastrointestinal transit rate. The relatively rapid gastric emptying and digestive processes allow an early expression of the acute effects of foods on the glucose response curve. Increasing the period of blood sampling beyond 90 min did not modify the discrimination between foods. We concluded that the diet consumed before the initiation of the study had not influenced the response to test foods and that an adaptation time appears to be unnecessary. The postprandial glycemic and insulin responses of normal dogs may be obtained after a single meal. We also conclude that a 90-min blood sampling period was sufficient to characterize the glycemic and insulin responses in normal dogs. KEY WORDS: * dog foods * glycemic response * insulinemic response * dogs