Dietary magnesium supplementation in cats with chronic kidney disease: A prospective double-blind randomized controlled trial.

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 (ß, 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 (ß, 0.14 ± .05 pg/mL/month; P = .01), but remained stable in the magnesium supplemented group (ß, 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.

The effect of obesity and subsequent weight reduction on cardiac morphology and function in cats.

BACKGROUND: In people, obesity is a risk factor for cardiovascular disease, associated with systemic hypertension, cardiac remodelling and systolic and diastolic dysfunction. Weight reduction can reverse myocardial remodelling and reduce risk of subsequent cardiovascular disease. In cats, far less is known regarding the effects of obesity and subsequent weight reduction on cardiovascular morphology and function. This prospective study aimed to assess cardiac morphology and function, heart rate variability, cardiac biomarkers and body composition before and after controlled weight reduction in cats with obesity. Body composition analysis (by dual energy x-ray absorptiometry, DEXA) and cardiovascular assessment (echocardiography, systemic arterial systolic blood pressure, electrocardiography, plasma cardiac biomarkers) were performed prior to weight management in twenty cats with obesity. These investigations were repeated in eleven cats that reached target weight. RESULTS: At baseline, systemic hypertension was not documented, but the majority of cats with obesity (15 out of 19) showed echocardiographic evidence of diastolic dysfunction. Eleven of 20 cats had increased maximal end-diastolic septal or left ventricular free wall thickness (≥ 6.0 mm) at baseline. Median (interquartile range) percentage of weight lost in the cats reaching target weight was 26% (17-29%), with a median reduction in body fat mass of 45% (26-64%). Both the end-diastolic left ventricular free wall (median magnitude of change -0.85 mm, IQR -0.05 mm to -1.55 mm, P = 0.019; median percentage reduction 14.0%) and end-diastolic interventricular septum (median magnitude of change -0.5 mm, IQR -0.2 mm to -1.225 mm, P = 0.047; median percentage reduction 7.9%) thickness decreased after weight reduction. Following weight reduction, pulsed wave tissue Doppler imaging of the left ventricular free wall was consistent with improved diastolic function in 4 out of 8 cats, however there was no significant difference in overall diastolic function class. Further, there was no change in heart rate variability or cardiac biomarkers with weight reduction. CONCLUSION: An increase in left ventricular wall thickness and diastolic dysfunction were common echocardiographic features in cats with obesity within our study and may be reversible with successful weight and fat mass loss. Further studies are required to clarify the clinical consequences of these findings.

Long-term safety of dietary salt: A 5-year ProspEctive rAndomized bliNded and controlled stUdy in healThy aged cats (PEANUT study).

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.

Partial weight reduction protocols in cats lead to better weight outcomes, compared with complete protocols, in cats with obesity.

Background: To date, there have been no studies comparing outcomes of cats with obesity following either complete or partial weight reduction protocols. Methods: Fifty-eight cats participated in this non-randomized observational cohort study, including 46 (79%) and 12 (21%) that underwent complete or partial weight reduction protocols, respectively. Weight loss outcomes, body composition changes and essential nutrient intake were compared between cats in the two groups. Results: All cats remained healthy, and those on a complete weight reduction protocol lost a median of 23% (range 10-39%) of starting body weight (SBW) over 294 days (113-967 days), whereas those undergoing partial restriction lost 25% (10-41%) over 178 days (54-512 days). Neither duration nor percentage weight loss differed between groups, but those that followed a partial weight reduction protocol lost weight at a faster rate (0.81% per week) and required fewer visits (4-19) than those that followed a complete weight reduction protocol (0.61% per week, p = 0.028; 11, 4-40 visits, p = 0.009). Further, lean tissue mass declined in cats on a complete weight reduction protocol (pre: 4.20 kg, 2.64-5.72 kg; post: 3.90 kg, 2.76-5.24 kg, p < 0.001), whereas lean tissue mass was unchanged in cats on partial weight reduction protocols (pre: 3.45 kg, 2.79-4.71 kg; post: 3.41 kg, 2.90-4.59 kg, p = 0.109). In 33 (57%) cats, median intake of selenium per day was less than NRC AI and RA recommendations, whilst intake was under FEDIAF recommendation in 42 (72%) cats. Median intake of choline per day was less than NRC MR and RA recommendations in 22 (38%) and 53 (91%) cats, respectively, whereas it was under the FEDIAF recommendation in 51 (88%) cats. In a small proportion (12-14%) of cats, phenylalanine/tyrosine and potassium were under recommendations; besides these, no other essential nutrient deficiencies were seen, and there were no differences between cats undergoing complete and partial weight reduction. Conclusion: Partial weight reduction protocols in cats lead to quicker average weight loss, with the possibility that lean tissue loss might be minimized. Such protocols might be more suitable for older cats and those with marked obesity.

The 13C-bicarbonate technique as a tool for measurement of energy expenditure in overweight dogs undergoing body weight reduction and the effect of different dietary composition.

Changes in body size and composition, i.e., body weight (BW) gain or loss, affect the daily energy expenditure (EE). To ensure an appropriate BW reduction and to find an efficient strategy to reduce and maintain a target BW, regular evaluations and adjustments of energy allowance are important. This study aimed to provide a detailed knowledge about the possible changes in resting EE using the oral 13C-bicarbonate technique (o13CBT) as a research tool in 16 overweight pet dogs undergoing BW reduction. Dietary composition (i.e., in % of dry matter [DM] being a high protein [33.3], low fat [9.6], and high crude fiber [18.0] diet [LFHFibre], and a high protein [37.9], high fat [52.0], carbohydrate-free diet [HFat]) during 16 wk of energy restriction were evaluated regarding effects on resting EE, rate of BW reduction, body composition, and plasma concentrations of metabolic hormones involved in energy metabolism and appetite regulation. The mean BW loss was higher (P < 0.05) for the dogs fed the LFHFibre diet (1.1%/wk) than that for dogs fed the HFat diet (0.8%/wk), but the total BW reduction of 14.6% and 12.0% of initial BW did not differ significantly (P > 0.05). Resting EE was lower (P < 0.02) after the BW reduction; 414 kJ (99 kcal)/kg BW0.75/d at the start (week 0) and 326 kJ (78 kcal)/kg BW0.75/d at the end (week 16) of the study. The BW reduction in both groups (P > 0.05) consisted of both fat mass (FM) and fat-free mass (FFM). Energy expenditure, calculated in relation to amount of FFM, was not significantly (P > 0.05) affected by BW reduction. Dietary composition did not significantly affect (P > 0.05) plasma concentrations of insulin, leptin, and ghrelin, and no effect (P > 0.05) of BW reduction was observed on hormone concentrations. In conclusion, the o13CBT proved to be a useful research method for studying short-term EE in overweight dogs. Even though all dogs lost BW, most dogs were still overweight at the end of the study. Due to a high individual variation among dogs, a longer experimental period with a larger sample size would be desirable.

The most common nutritional disorder in dogs is overweight, and knowledge about dogs' energy requirement is therefore important to adjust daily feed allowance. Changes in body weight may affect energy expenditure (EE) and, thereby, energy requirement. This study aimed to measure such potential changes under resting conditions in overweight dogs. It was found that the minimally invasive 13C-bicarbonate technique was a useful research method for studies regarding EE during weight loss (WL) in dogs. EE decreased when the dogs lost weight, and energy allowance needed to be reduced to maintain WL. The second objective of this study was to evaluate the effects of feeding diets with different macronutrient compositions on EE, rate of WL, body composition, and plasma concentrations of hormones involved in energy metabolism and appetite regulation. The mean WL rate was slightly higher for dogs fed a diet with high protein, low fat, and high crude fiber contents than those fed a carbohydrate-free diet with a high protein and fat contents. However, diet did not affect the resting EE, measured plasma hormone concentrations, or the total WL at the end of the study.

Life expectancy tables for dogs and cats derived from clinical data.

There are few recent and methodologically robust life expectancy (LE) tables for dogs or cats. This study aimed to generate LE tables for these species with clinical records from >1,000 Banfield Pet hospitals in the USA. Using Sullivan's method, LE tables were generated across survey years 2013-2019, by survey year, and for subpopulations defined by sex, adult body size group (purebred dogs only: toy, small, medium, large and giant), and median body condition score (BCS) over life. The deceased population for each survey year comprised animals with a recorded date of death in that year; survivors had no death date in that year and were confirmed living by a veterinary visit in a subsequent year. The dataset totaled 13,292,929 unique dogs and 2,390,078 unique cats. LE at birth (LEbirth) was 12.69 years (95% CI: 12.68-12.70) for all dogs, 12.71 years (12.67-12.76) for mixed-breed dogs, 11.18 years (11.16-11.20) for cats, and 11.12 (11.09-11.14) for mixed-breed cats. LEbirth increased with decreasing dog size group and increasing survey year 2013 to 2018 for all dog size groups and cats. Female dogs and cats had significantly higher LEbirth than males: 12.76 years (12.75-12.77) vs. 12.63 years (12.62-12.64), and 11.68 years (11.65-11.71) vs. 10.72 years (10.68-10.75), respectively. Obese dogs (BCS 5/5) had a significantly lower LEbirth [11.71 years (11.66-11.77)] than overweight dogs (BCS 4/5) [13.14 years (13.12-13.16)] and dogs with ideal BCS 3/5 [13.18 years (13.16-13.19)]. The LEbirth of cats with BCS 4/5 [13.67 years (13.62-13.71)] was significantly higher than cats with BCS 5/5 [12.56 years (12.45-12.66)] or BCS 3/5 [12.18 years (12.14-12.21)]. These LE tables provide valuable information for veterinarians and pet owners and a foundation for research hypotheses, as well as being a stepping-stone to disease-associated LE tables.

Plasma and Whole Blood Taurine Concentrations in Dogs May Not Be Sensitive Indicators of Taurine Deficiency When Dietary Sulfur Amino Acid Content Is Reduced.

Background: Taurine status is impacted by dietary supply of methionine and cysteine (SAA) and possibly intestinal microbial activity, where plasma and whole blood taurine concentrations are currently used to evaluate taurine status. Objective: We determined effects of dietary SAA restriction on rate and extent of taurine depletion of blood and skeletal muscle in dogs of two body sizes, and whether oral antibiotic administration affected the taurine depletion and fecal bile acid excretion of the dogs. Methods: Adult, male, Beagles (n = 6; 10.1-13.1 kg) and larger mixed-breed dogs (n = 6; 28.5-41.1 kg) were given four dry-expanded diets, whereby each successive diet contained lower protein and/or SAA concentration. After receiving the final diet for 44 weeks, all dogs were orally administered a mixture of ampicillin, neomycin sulfate, and metronidazole for 12 weeks. Taurine concentrations were determined every 2-4 weeks in venous blood and voided urine and every 4 to 16 weeks in biopsied semimembranosus muscle. Fecal bile acid excretion before and after antibiotics administration were quantified. Results: When given for 36 weeks the lowest SAA diet, 3.4% methionine and 2.9% cystine, taurine concentrations in whole blood were not different between groups, while taurine in plasma declined (P < 0.05) in large but not in small dogs, and taurine in biopsied muscle decreased (P < 0.05) by 50% in large and by 37% in small dogs. Concentrations of taurine in muscle were lower (P < 0.01) and fecal bile acids greater (P = 0.001) in large than small dogs. Antibiotic administration restored plasma and muscle taurine to initial concentrations and halved fecal bile acid excretion by dogs of both groups. Conclusions: Blood taurine concentration may not be a sensitive indictor of taurine depletion caused by low intake of bioavailable SAA in dogs, especially in large dogs. Taurine status and dietary SAA requirements of dogs may substantively depend on taurine loss mediated by intestinal microbiota.

Domestic Environment and Gut Microbiota: Lessons from Pet Dogs.

Accumulating data show the involvement of intestinal microbiota in the development and maintenance of numerous diseases. Many environmental factors influence the composition and function of the gut microbiota. An animal model subjected to the same environmental constraints that will allow better characterization of the microbiota-host dialogue is awaited. The domestic dog has physiological, dietary and pathological characteristics similar to those of humans and shares the domestic environment and lifestyle of its owner. This review exposes how the domestication of dogs has brought them closer to humans based on their intrinsic and extrinsic similarities which were discerned through examining and comparing the current knowledge and data on the intestinal microbiota of humans and canines in the context of several spontaneous pathologies, including inflammatory bowel disease, obesity and diabetes mellitus.

Aging in Cats: Owner Observations and Clinical Finding in 206 Mature Cats at Enrolment to the Cat Prospective Aging and Welfare Study.

Two hundred and six cats, aged between 7 and 10 years, from the North-west of the UK, were enrolled in a cat aging and welfare study to determine the frequency of age-related conditions and associations with husbandry, owner observations of physical appearance, activity and behavior. This is the largest study to date of mature cats that includes data from an owner questionnaire and clinical examinations. At enrolment, owners frequently reported physical changes (53%), behavioral changes (47%), changes to eating patterns (41%), and activity changes (40%) in their mature cats. On physical examination, 45% cats were in overweight condition and 12% were obese. A heart murmur was detected in 29% cats, whilst indirect systolic blood pressure (SBP) was >160 mmHg in 5% cats. Dental disease was present in 54% cats and was associated with a matted hair coat (P = 0.01), increased sleeping (P = 0.02), absence of gray hairs (P = 0.03), and increased irritability to other pets (P = 0.04). Abnormalities were evident in 58% of cats that allowed an orthopedic examination (OE) to be performed. These cats were older than cats with a normal OE (P = 0.01), and abnormal OE findings were associated with a matted coat (P = 0.03) and increased grooming (P = 0.04). Aazotaemia was present in 10% cats, and this was associated with cats being observed to "sniff their food and then walk away" (P = 0.04). Hyperthyroidism was diagnosed in 3% cats, who were older (P = 0.02), had a leaner BCS (P = 0.02) and lesser blood creatinine concentrations (P = 0.01). Hyperthyroid cats were also more likely to have increased liver enzyme activity and increased SBP (P = <0.001) compared with non-hyperthyroid cats. Of the 176 cats where all clinical assessments were conducted, only 12% had no evidence of any disease. Clinical abnormalities are commonly identified when thorough, clinical assessments are performed in mature pet cats visiting primary care practice.

Clinical progression of cats with early-stage chronic kidney disease fed diets with varying protein and phosphorus contents and calcium to phosphorus ratios.

BACKGROUND: Dietary protein and phosphorus (P) restriction is the mainstay for nutritional management of chronic kidney disease (CKD). However, adequate restriction levels for cats with early CKD remain unclear. OBJECTIVES: To investigate responses in cats with early CKD to varying dietary protein, P, and calcium (Ca) : P ratio. ANIMALS: Nineteen research colony cats with International Renal Interest Society stages 1-2 CKD. METHODS: In an opportunistic longitudinal case study, cats were fed a low protein (59 g/Mcal), low P (0.84 g/Mcal) dry diet (LP-LP; Ca : P = 1.9) for 18 months and later transitioned onto a moderate protein (76-98 g/Mcal), moderate P (1.4-1.6 g/Mcal) dry-wet diet regimen (MP-MP; Ca : P = 1.4-1.6) for 22 months. Fold-changes in serum creatinine, total Ca (tCa) and P (primary outcomes) and fibroblast growth factor 23 (FGF23) were assessed by linear-mixed models. RESULTS: While feeding LP-LP, mean serum creatinine decreased (0.87-fold, 95% confidence interval [CI] 0.81, 0.93, P < .001) to within reference range after 6 months, while increases in total Ca (tCa; 1.16-fold, 95% CI 1.11, 1.22, P < .001) and FGF23 (2.72-fold, 95% CI 1.72, 4.31, P < .001), but not in P (1.03-fold, 95% CI 0.945, 1.124, P = .94), were observed after 17 months. On MP-MP, mean creatinine, tCa and P remained within reference ranges and did not significantly change (P = .11, P = .98, and P = 1, respectively), while FGF23 significantly decreased (0.58-fold, 95% CI 0.36, 0.95, P = .02) after 22 months. CONCLUSIONS AND CLINICAL IMPORTANCE: Cats with early CKD developed hypercalcemia after long-term feeding of a highly P-restricted diet. Increasing dietary P and reducing Ca : P ratio maintained renal markers, while improving Ca-P balance. Cats with early CKD could benefit from moderately protein- and P-restricted diets.

Increasing Dietary Potassium Chloride Promotes Urine Dilution and Decreases Calcium Oxalate Relative Supersaturation in Healthy Dogs and Cats.

Urine dilution is a strategy used to decrease the risk of crystallization in cats and dogs at risk of urolithiasis. Sodium chloride has been used in prescription diets to effectively promote urine dilution, but the effect of the salt-substitute potassium chloride (KCl) on urine parameters has not been extensively investigated. Two diets differing only in KCl (Diet A; K 0.44 g/MJ, Diet B; K 1.03 g/MJ) were fed to 17 cats and 22 dogs for seven days, followed by three days of urine collection. Urinary ion concentrations were determined by ionic chromatography, and SUPERSAT software was used to calculate the relative supersaturation (RSS) value for struvite and calcium oxalate. Water intake and urine volume increased, and USG decreased on diet B (p < 0.001). Urine concentration of potassium increased on diet B, but concentrations of all other ions did not change or decrease in line with urine dilution. Calcium oxalate RSS decreased on diet B (p < 0.05). This short-term study showed that increased dietary KCl in a dry extruded diet effectively dilutes the urine of cats and dogs and therefore offers a novel nutritional strategy for the prevention of urolithiasis. This finding is of interest for patients that would benefit from dietary sodium restriction.

Towards establishing no observed adverse effect levels (NOAEL) for different sources of dietary phosphorus in feline adult diets: results from a 7-month feeding study.

High dietary phosphorus (P), particularly soluble salts, may contribute to chronic kidney disease development in cats. The aim of the present study was to assess the safety of P supplied at 1 g/1000 kcal (4184kJ) from a highly soluble P salt in P-rich dry format feline diets. Seventy-five healthy adult cats (n 25/group) were fed either a low P control (1·4 g/1000 kcal [4184kJ]; Ca:P ratio 0·97) or one of two test diets with 4 g/1000 kcal (4184 kJ); Ca:P 1·04 or 5 g/1000 kcal (4184kJ); Ca:P 1·27, both incorporating 1 g/1000 kcal (4184 kJ) sodium tripolyphosphate (STPP) - for a period of 30 weeks in a randomised parallel-group study. Health markers in blood and urine, glomerular filtration rate, renal ultrasound and bone density were assessed at baseline and at regular time points. At the end of the test period, responses following transition to a commercial diet (total P - 2·34 g/1000 kcal [4184kJ], Ca:P 1·3) for a 4-week washout period were also assessed. No adverse effects on general, kidney or bone (skeletal) function and health were observed. P and Ca balance, some serum biochemistry parameters and regulatory hormones were increased in cats fed test diets from week 2 onwards (P ≤ 0·05). Data from the washout period suggest that increased serum creatinine and urea values observed in the two test diet groups were influenced by dietary differences during the test period, and not indicative of changes in renal function. The present data suggest no observed adverse effect level for feline diets containing 1 g P/1000 kcal (4184 kJ) from STPP and total P level of up to 5 g/1000 kcal (4184 kJ) when fed for 30 weeks.

The effect of attenuating dietary phosphate restriction on blood ionized calcium concentrations in cats with chronic kidney disease and ionized hypercalcemia.

BACKGROUND: Hypercalcemia is commonly observed in cats with azotemic chronic kidney disease (CKD). Dietary phosphate restriction is considered standard of care but may contribute to the development of hypercalcemia. The optimal dietary management strategy for these cats is unclear. OBJECTIVES: To describe the effect of feeding a moderately phosphate-restricted diet (MP; 1.5 g/Mcal phosphorus; Ca : P ratio, 1.3) to cats with concurrent azotemic CKD and ionized hypercalcemia. ANIMALS: Client-owned cats with ionized hypercalcemia (ionized calcium [iCa] concentration >1.4 mmol/L) at diagnosis of CKD (n = 11; baseline hypercalcemics) or after CKD diagnosis while eating a phosphate-restricted clinical renal diet (0.8 g/Mcal phosphorus; Ca : P ratio, 1.9; n = 10; RD hypercalcemics). METHODS: Changes in variables over time, after starting MP at visit 1, were assessed using linear mixed model analysis within each group of cats. Data are reporte as median [25th, 75th percentiles]. RESULTS: At visit 1, iCa was 1.47 [1.42, 1.55] mmol/L for baseline hypercalcemics and 1.53 [1.5, 1.67] mmol/L for RD hypercalcemics. Blood iCa decreased (P < .001) when RD hypercalcemics were fed MP, with iCa <1.4 mmol/L in 8/10 cats after 2.2 [1.8, 3.7] months. Plasma phosphate concentrations did not change. In contrast, the baseline hypercalcemic group overall showed no change in iCa but a decrease in plasma phosphate concentration during 8.8 [5.5, 10.6] months on the MP diet, although 4/11 individual cats achieved iCa <1.4 mmol/L by 3.4 [1.0, 6.2] months. CONCLUSIONS AND CLINICAL IMPORTANCE: Attenuation of dietary phosphate restriction could result in normalization of iCa in cats that develop hypercalcemia while eating a clinical renal diet.

The effect of urine acidification on calcium oxalate relative supersaturation in cats.

There is an apparent reciprocal relationship between magnesium ammonium phosphate (MAP, struvite) and calcium oxalate (CaOx) urolithiasis incidence rate in cats. The number of struvite uroliths submitted for analysis over the past 35 years has been decreasing, with an increase in CaOx urolith submissions. Commercial diets aimed to dissolve struvite uroliths are typically acidified, and it has been suggested that dietary acidification increases urinary calcium excretion and the risk of CaOx crystallization. The objective of this study was to assess the effect of urine acidification on the relative supersaturation (RSS) of CaOx in cats, as a representation of crystallization risk. Four diets were extruded to contain identical nutrient contents, but with gradual acidification (0, 0.6, 1.3 and 1.9% sodium bisulphate substituted sodium chloride in diets A, B, C and D respectively). Thirteen adult cats were fed each diet sequentially for a minimum of 10 days. Average urine pH was 6.4, 6.2, 6.0 and 5.9 on diets A, B, C and D respectively (p < 0.0001). Struvite RSS decreased on diets inducing more acidic urine pH (p < 0.0001). Urinary calcium excretion and concentration increased with diets inducing lower urine pH (p < 0.0001), but oxalate excretion and concentration decreased (p < 0.001). CaOx RSS was not different between diets (p = 0.63). These results suggest that a lower diet base excess and resulting urine pH to support struvite dissolution do not increase the risk for CaOx crystallization in the range of urine pH representative of most commercial feline diets. Long-term studies are needed to confirm this.

Effects of High-Fat Diet at Two Energetic Levels on Fecal Microbiota, Colonic Barrier, and Metabolic Parameters in Dogs.

Increased consumption of energy-rich foods is a key factor in overweight, obesity, and associated metabolic disorders. This would be, at least in part, related to microbiota disturbance. In rodent models of obesity, microbiota disruption has been associated with alteration of the intestinal barrier, endotoxemia, inflammation grade, and insulin sensitivity. The aim of the present study was to assess the effects of a high-fat diet (HFD), fed at two energetic levels, on microbiota, intestinal barrier, and inflammatory and metabolic parameters in dogs. A HFD (33% fat as fed, 4,830 kcal/kg) was given to 24 healthy Beagle dogs at 100% (HF-100; n = 8) and at 150% (HF-150; n = 16) of their maintenance energy requirements for 8 weeks. Analysis of similarity revealed a significant difference in gut microbiota ß-diversity following the diet compared to week 0 in both groups while α-diversity was lower only in the HF-150 group. Firmicutes/Bacteroidetes ratio was higher in the HF-150 group compared to the HF-100 group at weeks 2 and 8. A reduction in insulin sensitivity was observed over time in the HF150 group. Neither endotoxemia nor inflammation was observed in either group, did not find supporting data for the hypothesis that the microbiota is involved in the decline of insulin sensitivity through metabolic endotoxemia and low-grade inflammation. Colonic permeability was increased at week 4 in both groups and returned to initial levels at week 8, and was associated with modifications to the expression of genes involved in colonic barrier function. The increase in intestinal permeability may have been caused by the altered intestinal microbiota and increased expression of genes encoding tight junction proteins might indicate a compensatory mechanism to restore normal permeability. Although simultaneous changes to the microbiota, barrier permeability, inflammatory, and metabolic status have not been observed, such a causal link cannot be excluded in dogs overfed on a HFD. Further studies are necessary to better understand the link between HFD, intestinal microbiota and the host.

An artificial neural network-based model to predict chronic kidney disease in aged cats.

BACKGROUND: Chronic kidney disease (CKD) frequently causes death in older cats; its early detection is challenging. OBJECTIVES: To build a sensitive and specific model for early prediction of CKD in cats using artificial neural network (ANN) techniques applied to routine health screening data. ANIMALS: Data from 218 healthy cats ≥7 years of age screened at the Royal Veterinary College (RVC) were used for model building. Performance was tested using data from 3546 cats in the Banfield Pet Hospital records and an additional 60 RCV cats-all initially without a CKD diagnosis. METHODS: Artificial neural network (ANN) modeling used a multilayer feed-forward neural network incorporating a back-propagation algorithm. Clinical variables from single cat visits were selected using factorial discriminant analysis. Independent submodels were built for different prediction time frames. Two decision threshold strategies were investigated. RESULTS: Input variables retained were plasma creatinine and blood urea concentrations, and urine specific gravity. For prediction of CKD within 12 months, the model had accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 88%, 87%, 70%, 53%, and 92%, respectively. An alternative decision threshold increased specificity and PPV to 98% and 87%, but decreased sensitivity and NPV to 42% and 79%, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: A model was generated that identified cats in the general population ≥7 years of age that are at risk of developing CKD within 12 months. These individuals can be recommended for further investigation and monitoring more frequently than annually. Predictions were based on single visits using common clinical variables.

Use of reduced-energy content maintenance diets for modest weight reduction in overweight cats and dogs.

One option for controlled weight loss for dogs and cats in overweight condition could be to modestly restrict caloric intake using a reduced-energy ('light') maintenance diet, but there is no prior research on the safety and efficacy of such an approach. A prospective observational cohort study was performed in 67 overweight dogs and 17 overweight cats undergoing weight loss using reduced-energy maintenance diets from one manufacturer. Diets were fed at approximately 80% of maintenance energy requirements for ideal bodyweight for a period of 8 weeks. Essential nutrient intake was estimated for each dog and cat and compared with minimum requirement (MR) or adequate intake (AI, when no MR had been demonstrated) as set by the National Research Council in 2006. Weight loss was seen in 56/67 dogs (84%), losing a median of 4.7% (range 15.2% loss to 10.0% gain) of their starting body weight (SBW). Weight loss was also seen in all 17 cats, losing a median of 6.4% (range 2.0 loss to 15.2% loss) of SBW. Of the essential nutrients examined, only selenium, choline, potassium, and riboflavin were less than NRC recommendations in a minority of animals. However, no signs of any nutrient deficiency were observed in any of the dogs or cats during the study. In summary, modestly energy restricting overweight dogs and cats when feeding a low-energy maintenance diet can induce weight loss and might be a useful initial step for weight management. Although no adverse effects were seen, borderline intake of some micronutrients warrants further consideration.

Comparison of clinical, endoscopic, and histologic features between dogs with chronic gastritis with and without lymphofollicular hyperplasia.

OBJECTIVE: To compare clinical, endoscopic, and histopathologic features between dogs with chronic gastritis (CG) with and without lymphofollicular hyperplasia (LFH). ANIMALS: 64 and 56 dogs with CG with (cases) and without (controls) LFH, respectively. PROCEDURES: The medical record database of a referral clinic was searched to identify dogs that underwent endoscopic examination of the upper portion of the gastrointestinal tract and were subsequently determined to have CG with or without LFH between October 2006 and February 2011. Signalment and clinical, endoscopic, and histologic findings were compared between cases and controls. Logistic regression was used to identify factors associated with CG with LFH. RESULTS: Compared with controls, cases were significantly younger and more likely to be of a brachycephalic phenotype. The proportions of dogs with a poor body condition or diarrhea were significantly lower and the proportions of dogs with inspiratory dyspnea, exercise intolerance, or hyperemia and discoloration of the gastric mucosa were significantly higher for the case group, compared with the control group. Inspiratory dyspnea, gastric mucosal hyperemia, and gastritis severity were positively associated, whereas poor body condition was negatively associated, with CG with LFH on multivariable logistic regression. CONCLUSIONS AND CLINICAL RELEVANCE: The strong positive association between inspiratory dyspnea and CG with LFH suggested that the condition may be a consequence of an increase in negative intrathoracic pressure rather than a distinct clinical entity. Prospective studies are warranted to elucidate the mechanism by which inspiratory dyspnea contributes to the development of CG with LFH.

Increasing dietary sodium chloride promotes urine dilution and decreases struvite and calcium oxalate relative supersaturation in healthy dogs and cats.

Urolithiasis is highly prevalent in dogs and cats, with struvite and calcium oxalate being most commonly diagnosed. Some commercial diets aimed at reducing the risk of urolithiasis are based on inclusion of sodium chloride (NaCl) in an attempt to dilute the urine and the risk of crystallization, but more information on the effect of differing levels of sodium inclusion is needed. The objective of this study was to compare the short-term effect of four diets differing only in NaCl content (base diet with 0.3% sodium and diets with added NaCl to achieve 0.7, 1.0 and 1.3% sodium as fed) on urinary ion concentrations and relative supersaturation (RSS) of struvite and calcium oxalate in dogs and cats. In both species, there was a significant increase in water intake and urine volume as dietary NaCl increased. Urine sodium concentration increased with increasing dietary NaCl. The highest sodium diet increased urinary calcium excretion in dogs only, while decreasing urinary calcium concentration. Calcium oxalate RSS and struvite RSS both significantly decreased, with the lowest RSS values reported on the highest sodium diet in both dogs and cats (p < .001). These results suggest that an increase in dietary NaCl decreases RSS values in both dogs and cats. Despite an increase in urinary calcium excretion in dogs, urinary calcium concentration and calcium oxalate RSS were lower on high sodium diets due to urine dilution. Long-term studies are needed to confirm the relationship between RSS and stone occurrence and recurrence.

Fibroblast growth factor 23 and symmetric dimethylarginine concentrations in geriatric cats.

BACKGROUND: Fibroblast growth factor 23 (FGF23) is a phosphaturic hormone that is increased in azotemic cats with chronic kidney disease (CKD) and predictive of the onset of azotemia in older cats. The introduction of symmetric dimethylarginine (SDMA) as a biomarker of glomerular filtration rate has led to the identification of cats in which SDMA is increased, but plasma creatinine concentrations remains within reference range. There is currently little understanding of the metabolic changes present in such cats. OBJECTIVES: To examine the relationship between plasma FGF23 and SDMA concentrations in non-azotemic geriatric cats. ANIMALS: Records of a cross section of client-owned cats (n = 143) without azotemic CKD. METHODS: Clinicopathological information was obtained from cats (≥ 9 years) from records of 2 first opinion practices. The relationship between plasma SDMA and FGF23 concentrations was examined using Spearman's correlation and variables compared using the Mann-Whitney U test. RESULTS: Cats with increased SDMA concentrations had significantly higher plasma FGF23 (P < .001) and creatinine (P < .001) concentrations compared to cats with SDMA concentrations within reference range. A weak positive relationship was demonstrated between plasma FGF23 and SDMA concentrations (r = .35, P < .001) and between plasma FGF23 and creatinine (r = .23, P = .005) concentrations. CONCLUSIONS AND CLINICAL IMPORTANCE: More cats with increased SDMA concentrations had higher FGF23 concentrations than those with SDMA concentrations within the reference range, suggesting the presence of an alteration in phosphate homeostasis. Further studies are warranted to identify influencing factors and to explore the utility of FGF23 concentration to inform management of cats with early stage CKD.