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.

Supplementation of vitamin E as an addition to a commercial renal diet does not prolong survival of cats with chronic kidney disease.

BACKGROUND: The aim of this double-blind, placebo-controlled study was to investigate the effect of vitamin E supplementation as an addition to a commercial renal diet on survival time of cats with different stages of chronic kidney disease (CKD). In addition, we were interested whether vitamin E supplementation affects selected oxidative stress and clinical parameters. Thirty-four cats with CKD and 38 healthy cats were included in the study. Cats with CKD were classified according to the IRIS Guidelines; seven in IRIS stage 1, 15 in IRIS stage 2, five in IRIS stage 3 and seven in IRIS stage 4. Cats with CKD were treated according to IRIS Guidelines. Cats with CKD were randomly assigned to receive vitamin E (100 IU/cat/day) or placebo (mineral oil) for 24 weeks in addition to standard therapy. Plasma malondialdehyde (MDA) and protein carbonyl (PC) concentrations, DNA damage of peripheral lymphocytes and plasma vitamin E concentrations were measured at baseline and four, eight, 16 and 24 weeks thereafter. Routine laboratory analyses and assessment of clinical signs were performed at each visit. RESULTS: Vitamin E supplementation had no effect on the survival time and did not reduce the severity of clinical signs. Before vitamin E supplementation, no significant differences in vitamin E, MDA and PC concentrations were found between healthy and CKD cats. However, plasma MDA concentration was statistically significantly higher (p = 0.043) in cats with early CKD (IRIS stages 1 and 2) than in cats with advanced CKD (IRIS stages 3 and 4). Additionally, DNA damage was statistically significantly higher in healthy cats (p ≤ 0.001) than in CKD cats. Plasma vitamin E concentrations increased statistically significantly in the vitamin E group compared to the placebo group four (p = 0.013) and eight (p = 0.017) weeks after the start of vitamin E supplementation. During the study and after 24 weeks of vitamin E supplementation, plasma MDA and PC concentrations and DNA damage remained similar to pre-supplementation levels in both the placebo and vitamin E groups. CONCLUSIONS: Vitamin E supplementation as an addition to standard therapy does not prolong survival in feline CKD.

Nutritional management of pancreatitis and concurrent disease in dogs and cats.

Nutrition is considered a key part of the management of pancreatitis in dogs and cats. While limited prospective research exists, experimental studies, retrospective studies, and anecdote allow for formulation of nutritional guidelines. Historically, fat has been considered the key nutrient of interest in pancreatitis; however, other nutrients and dietary factors, including energy density, digestibility, protein, carbohydrates, and fiber, are all of importance in these patients. Indeed protein particle size may be of greater significance than dietary fat in the management of pancreatitis in cats. Low-fat gastrointestinal diets are frequently recommended in the initial management of pancreatitis in dogs, while hydrolyzed diets are often considered first-line diets in cats with pancreatitis. The presence or absence of comorbid disease may also alter nutritional recommendations. When diseases occur concurrently, the dietary strategies for the most life-threatening illness, or the illness with the greatest impact on quality of life, is recommended to be prioritized. Many dogs and cats with pancreatitis can be transitioned back to their prediagnosis diet or another commercial maintenance diet, provided that significant comorbid disease is absent. Use of a low-fat diet in the long term may be prioritized in dogs with recurrent episodes of pancreatitis.

Dietary and Nutritional Approaches to the Management of Chronic Enteropathy in Dogs and Cats.

Nutrition can influence those functions of the gastrointestinal tract that can be adversely affected in chronic enteropathy, such as microbiota, mucosal immune system, intestinal permeability, and motility. Diet serves as a possible risk factor in disease pathogenesis and as a target for treatment in chronic enteropathy. Malnutrition is prevalent in people with inflammatory bowel disease and negatively affects outcome. Approximately two-thirds of dogs with protein-losing enteropathy due to chronic enteropathy or lymphangiectasia are underweight. Commercial diets and home-prepared diets have been used successfully in the management of chronic enteropathy. Fat restriction is the main dietary strategy for intestinal lymphangiectasia.

Dietary intake of amino acids and vitamins compared to NRC requirements in obese cats undergoing energy restriction for weight loss.

BACKGROUND: This study aimed to determine if obese cats undergoing energy restriction for weight loss would meet the National Research Council's (NRC) indispensable amino acid and vitamin recommendations when fed a purpose-formulated diet. Thirty cats were placed into one of two groups; obese (BCS 8 to 9/9; n = 16) and lean (BCS 4 to 5/9; n = 14) and included in a non-randomized retrospective observational study. Cats were fed a veterinary weight loss food during a 4-week period of weight maintenance. Obese cats (O-MAINT) refers to obese cats during this period, L-MAINT to lean cats. After this initial 4-week period, the lean cats finished the study at this time and the 16 obese cats continued and were energy restricted for a 10-week period (O-RESTRICT). Analysis for dietary concentrations of indispensable amino acid and vitamin contents were performed. Daily food intakes were used to determine minimum, maximum and average daily intakes of individual nutrients for all three groups and compared against NRC 2006 minimum requirements (MR), adequate intakes (AI) and recommended allowances (RA) for adult cats. RESULTS: Over 10 weeks, O-RESTRICT cats lost 672 g ± 303 g, representing a weight loss rate of 0.94 ± 0.28% per week. Daily intake of the majority of indispensable amino acids and vitamins was greater than the NRC 2006 recommended allowance (RA per kg ideal body weight ^0.67), except for arginine, choline, crude protein, phenylalanine plus tyrosine and threonine. All O-RESTRICT cats had minimum, average, and maximum arginine intakes less than the NRC AI. Minimum daily intake of choline was below NRC RA for all O-RESTRICT cats and below NRC MR for two. All, except one, O-RESTRICT cats had a maximum and average choline intake below RA. CONCLUSIONS: All cats remained clinically healthy and showed no clinical signs of deficiency. Dietary choline and arginine requirements of obese cats as well as health risks associated with low dietary intake during energy restriction warrant further investigation.

Understanding the Nutritional Needs of Healthy Cats and Those with Diet-Sensitive Conditions.

Diets for cats must provide complete nutrition and meet the needs of the individual patient. There is no single diet that is perfect for all cats, and veterinarians must consider the needs of the cat as well as the preferences of the owners when making dietary recommendations. This article focuses on the interface between animal factors and nutritional needs in cats and is divided into 3 sections. Section 1 addresses the dietary needs of healthy cats, including differences among life stages. Section 2 addresses common myths regarding feline nutrition. Section 3 addresses common nutrient-sensitive conditions in cats, including sarcopenia of aging.

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.

The effect of a therapeutic urinary stress diet on the short-term recurrence of feline idiopathic cystitis.

The aim of this cohort study was to evaluate the effect of a therapeutic urinary stress diet on recurrent clinical signs of lower urinary tract disease in cats with idiopathic cystitis. The effects of feeding a therapeutic urinary stress diet were compared with feeding a non-therapeutic diet for a duration of 5 weeks. The owners selected themselves which food to feed their cat. Of 31 cats with acute non-obstructive idiopathic cystitis, 17 were fed the test food and 14 the control food. An episode of recurrence was defined as a minimum of one day with at least two clinical signs; i.e. stranguria, periuria, haematuria, dysuria and pollakiuria. The number of cats fed the therapeutic urinary stress diet that had an episode of recurrence (5/17) was significantly lower compared with cats that were fed other commercial diets (11/14). The formulation of the foods fed to the participating cats (dry, moist or a combination of both) was not found significant compared with the recurrence of idiopathic cystitis. Apart from type of diet, no other risk factors affected the short-term recurrence of FIC. A prospective clinical trial is needed to confirm these findings.

Concentrations of leptin, adiponectin, and resistin in the serum of obese cats during weight loss.

We monitored changes in serum leptin, adiponectin, and resistin concentrations in obese cats during weight loss. Six naturally developed obese cats were fed low-fat, high-fiber dry food during a 9-week experimental period. Serum leptin, adiponectin, and resistin concentrations were measured at week 0, 4, 8, and 9. Body weight became significantly lower week 4 onward than that at week 0 (P<0.05 or 0.01). At week 9, serum leptin concentrations were significantly lower than those at week 0 (P<0.05). Contrarily, serum adiponectin and resistin concentrations did not significantly differ within the 9 weeks. While serum leptin levels were strongly positively correlated with body weight (r=0.923, P<0.001), serum adiponectin levels were moderately negatively correlated with it (r=-0.529, P<0.01), with serum resistin having a no correlation with body weight. Serum leptin levels might be more closely related with pathogenesis of adiposity than serum adiponectin or resistin in cats.

Male and female cats have different regional body compositions and energy requirements for weight loss and weight maintenance.

Body composition and energy requirements are different between males and females in several species, and both interfere with weight loss. The aim of this study was to compare the total and regional body composition and energy requirements in obese male (n = 8) and female (n = 8) cats, during weight loss and weight maintenance over 17 subsequent weeks after regimen. The total and regional (thoracic and pelvic limbs, and trunk) body composition was assessed by dual-energy X-ray absorptiometry (DXA). Females exhibited a higher fat mass (FM) than males (p < 0.05), and the trunk was the site with greater fat accumulation regardless of gender. A 23.0 ± 2.8% reduction in body weight was followed by a 50.3 ± 9.4% and a 37.0 ± 8.9% reduction in fat in the trunk region in males and females respectively. Lean mass (LM) mobilization was also increased in the trunk (p < 0.05), and the loss of LM was associated with a reduction in bone mass. The energy intake to achieve the same rate of weight loss was 12.9 ± 3.4% higher in males (p < 0.05). The cats exhibited a gradual increase in energy requirements to maintain their body weight after weight loss (p < 0.05). It was concluded that obese cats mainly accumulate fat in the trunk. The reduction in lean mass after the regimen also occurred in the trunk, with no modifications in the skeletal muscle mass of the limbs. Neutered male cats have higher energy requirements than neutered females, and gender should be considered during obesity management in cats.

Diabetic cats have decreased gut microbial diversity and a lack of butyrate producing bacteria.

Obesity and inactivity are major risk factors of feline diabetes mellitus (FDM) and human type II diabetes mellitus (T2DM). In recent years, changes in the gut microbiota have been suggested as a contributing factor to T2DM. Whether the gut microbiota (GM) composition plays a role in FDM remains unknown. The aim of the current study was firstly a cross-sectional comparison of the GM of diabetic cats, to that of lean, and of obese/overweight non-diabetic cats of a similar age. Specifically, fecal samples from 82 privately-owned cats from Denmark and Switzerland were sequenced using 16S rRNA gene amplicon metabarcoding. Secondly dietary intervention data was generated, by obtaining additional samples from a subset of cats after placing them on a high-protein diet for four weeks. The GM diversity of diabetic cats was lower than that of lean cats in the cross-sectional study, and lower compared to lean and to overweight/obese cats after diet intervention. Diabetic cats also exhibited fewer Anaerotruncus, Dialister, and unknown Ruminococcaceae than lean cats. Serum fructosamine levels correlated negatively with Prevotellaceae abundance and positively with Enterobacteriaceae abundance. In summary the intestinal microbiota of diabetic cats was characterized by decreased GM diversity and loss of butyrate producing bacterial genera.

Narrative review of therapies for chronic enteropathies in dogs and cats.

BACKGROUND: The optimal medical treatment for chronic enteropathy (CE) in dogs and cats is controversial. Sequential treatment using diet, antimicrobials, and immunosuppressive drugs is the most common strategy used by clinicians. OBJECTIVES: To review the evidence for the effectiveness of dietary, drug, and alternative health interventions for inducing clinical remission in dogs and cats with CE. ANIMALS: Retrospective study of dogs and cats with a diagnosis of chronic enteropathy. METHODS: MEDLINE and Centre for Agriculture and Bioscience International (CABI) databases (1950 to March 2017) were searched for randomized controlled trials (RCTs), observational studies, and case series. The primary outcome was induction of clinical remission. All studies were evaluated using the quality of evidence grading guidelines (I-IV), which assign a score defining the strength and quality of the evidence. RESULTS: Twenty-two studies (11 RCTs in dogs and 2 in cats and 9 cohort studies or case series) met the inclusion criteria for inducing remission of gastrointestinal (GI) signs. Of the 13 RCTs achieving grade I scores, 10 studies (totaling 218 dogs and 65 cats) compared single treatment: diet (n = 3), immunosuppressives (n = 3), antimicrobials (n = 2), anti-inflammatory drugs (n = 1), and probiotics (n = 1). Three case series (grade III) reported clinical remission using an elimination diet fed to 55 cats and use of enrofloxacin to induce remission in dogs with granulomatous colitis (2 studies totaling 16 dogs). CONCLUSIONS AND CLINICAL IMPORTANCE: The current evidence for treatment of CE is much greater in dogs than in cats. There is sufficient strong evidence to recommend the use of therapeutic GI diets, glucocorticoids, enrofloxacin, or some combination of these in dogs with CE. Therapeutic GI diets and glucocorticoids are most useful in cats with CE.

Nutritional Management of Urolithiasis.

Dietary management of urolithiasis in dogs and cats is designed to dissolve calculi when possible and/or reduce the risk of recurrence. The diet must reduce urine relative supersaturation for the particular salt in order to prevent crystallization. To decrease urinary concentrations of crystal precursors, increasing water intake is essential regardless of the stone type. Altering the amounts of dietary precursors of the stone and controlling urine pH is mostly effective for struvite, urate, xanthine, and cystine, but still subject to controversy for calcium oxalate. The investigation of underlying metabolic disorders and close monitoring of animals at risk is recommended.

The use of hyaluronic acid subdermal filler for entropion in canines and felines: 40 cases.

PURPOSE: To evaluate the use of hyaluronic acid (HA) subdermal filler in canines and felines for entropion. METHODS: Complete ophthalmologic examination was performed by a board-certified veterinary ophthalmologist or ABVO-approved resident. Each case was characterized as primary, secondary, spastic or cicatricial entropion. HA subdermal filler, specifically Restylane® and Restylane Silk® , were utilized in dogs and cats, respectively. Subdermal injection was performed 1-2 mm from the eyelid margin in the affected area until normal eyelid conformation was achieved. All patients did not require sedation or general anesthesia. RESULTS: Forty animals (28 dogs and 12 cats) were included in the study. No local reaction to the HA dermal filler or any other complications other than minor skin bleeding at the injection sites were noted in all patients. Resolution of entropion and secondary complications including corneal ulceration, epiphora, and blepharospasm were noted by the first week after injection in the majority of cases. Three canines and one feline case failed to resolve the entropion, necessitating additional permanent surgical intervention. Two cases were submitted for histopathological analysis. Median follow-up time for all cases was 152.5 days (mean: 194.6 ± 142.7 days; range 9-419 days). Five patients died or were euthanized during the study for unrelated causes. CONCLUSIONS: Hyaluronic acid (HA) subdermal filler appears to be a safe, easy, reliable method for mild to moderate eyelid entropion not requiring general anesthesia. This procedure may be especially appropriate for geriatric patients and those with high anesthetic risk with entropion.

Factors associated with overweight cats successfully completing a diet-based weight loss programme: an observational study.

BACKGROUND: The most common approach for controlled weight loss in cats is dietary caloric restriction, using a purpose-formulated diet. Most previous studies have only assessed short-term outcomes, and no previous study has examined overall success (i.e. odds of reaching target weight). The aim of this study was to determine the factors associated with overweight cats successfully completing a diet-based weight loss programme to reach target weight. RESULTS: Sixty-two cats were included, and 28 (45%) completed their weight loss programme. The remaining 34 cats (55%) did not reach target weight, of which 2 (3%) were euthanised for unrelated reasons. Reasons for cats stopping the programme prematurely included inability to contact owner (n = 19), owner requested that the programme be completed prior to reaching target weight (n = 5), the cat developed another illness (n = 3), refusal to comply with requirements for weight management (n = 2), owner illness (n = 2), and personal issues of the owner (n = 1). Multiple logistic regression analysis revealed that rate of weight loss and weight loss required were positively (odds ratio [OR] 157.81, 95% confidence interval [CI] 10.00-2492.67) and negatively (OR 0.89, 95% CI 0.81-0.98) associated with the odds of completing the weight loss programme, respectively. CONCLUSIONS: Future studies should consider developing better methods of supporting the owners of the most obese cats during weight management, since these cats are least likely to complete reach target weight.

An international multi-centre cohort study of weight loss in overweight cats: Differences in outcome in different geographical locations.

INTRODUCTION: Feline obesity is a worldwide concern which has recently been formally classified as a disease by the veterinary community. Management involves invoking controlled weight loss by feeding a purpose-formulated food in restricted quantities and altering physical activity. Most weight loss studies conducted in cats have been undertaken in research cat colonies from single geographic locations. The aim of this multi-centre cohort study was to determine the efficacy of a short-term dietary weight loss intervention in overweight pet cats across a range of geographical locations globally. MATERIALS AND METHODS: A 3-month (median 13 weeks, inter-quartile range [IQR] 12-15 weeks) weight loss programme was conducted at 188 veterinary practices in 22 countries, and involving 730 cats, 413 of which completed the programme and had complete data available. All were fed commercially available dry or wet weight loss diets, and median energy intake was 53 kcal/kg BW0.711/day. The Royal Canin Ethics Committee approved the study, and owners gave informed consent. Owners completed behavioural questionnaires assessing begging, physical activity and quality of life (QOL). Linear mixed models were used to assess the respective influence of time, age, and initial body condition score (BCS) on weight loss and behavioural observations. RESULTS: At baseline, median age was 72 months (range 12-200 months) and median BCS was 8 (range 7-9). In all, 402/413 cats (97%) lost weight (mean 10.6±6.3%) during the programme at a rate of 0.8 ±0.50%/week. Based upon owner questionnaires, activity and QOL improved (both P<0.001), while begging behaviour decreased (P<0.001) during weight loss. The main factor influencing percentage weight loss was geographical location (P<0.001), with cats in North America losing less weight (median 7.2%, IQR: 4.4-10.4%) than those in both Europe (10.7%, 6-8-15.4%) and South America (10.0%, 6.2-15.4%). Differences in weight loss were also observed amongst countries (P<0.001), with cats in Argentina, Germany, and Italy losing more weight than cats in the USA, and cats in Germany also losing more weight than cats in Portugal. DISCUSSION/CONCLUSION: Most of the overweight cats enrolled in this international multi-centre study successfully lost weight. The reason for the differences in percentage weight loss amongst geographical locations requires further study.

A nutraceutical diet based on Lespedeza spp., Vaccinium macrocarpon and Taraxacum officinale improves spontaneous feline chronic kidney disease.

Chronic kidney disease is characterized by structural and/or functional impairment of one or both kidneys persisting for more than 3 months. In cats, chronic kidney disease can frequently occur in animals aged over 9 years with an incidence of approximately 10%. Thirty-four client-owned, neutered cats, suffering from stage II-III chronic kidney disease and diagnosed according to the International Renal Interest Society guidelines were randomly assigned to receive either a control diet (n = 17) or a nutraceutical diet (ND; n = 17) for 90 days. Both diets were commercialized for management of CKD symptoms. The diets were identical except that the ND contained tablets that consisted of 60-80% hydrolysed proteins, 20-40% minerals and active substances, that are, Lespedeza spp. 0.0588%, Vaccinium macrocarpom 0.0371%, and Taraxacum officinale 0.0231%. No adverse effects were reported during this study. Both diets resulted in an improvement in CKD symptoms. After a 90-day evaluation, creatinine, blood urea nitrogen, total proteins, and aspartate aminotransferase significantly decreased in cats that received the ND. A significant decrease was also observed in urine turbidity score, color score, and total proteins in cats that received the ND. We have found that a ND based on Lespedeza spp., Vaccinium macrocarpon, and Taraxacum officinale improves key indicators of renal failure in cats affected by chronic kidney disease.

A long term feed supplementation based on phosphate binders in Feline Chronic Kidney Disease.

Chronic kidney disease (CKD) is a very common disorder in elderly cats. A proper renal diet represents the most efficient therapeutic intervention to improve survival and life quality in feline patients with 3 and 4 International Renal Interest Society (IRIS) stages. Twenty cats were selected in this study. Ten were administered the dietary supplementation for 360 days and the other ten, whose owners did not give consent for any supplemental therapies apart from the renal diet, were selected from a clinical database and used as control group. The present study is a long term study (360 days) aiming to evaluate the efficacy and palatability of a dietary supplementation containing calcium carbonate, calcium-lactate gluconate, chitosan and sodium bicarbonate in cats diagnosed with 3 and 4 IRIS stages of CKD. The owners were asked to fill in questionnaires to get information on the cat's appetite, the palatability of the given supplement, the presence of vomit and/or diarrhoea, general health and vitality. Hematochemical, biochemical and urinary analyses were performed on day 0, 30, 60, 90, 120, 150,180 and 360. GraphPad Prism® software was used to perform statistical analysis. Our study shows that the given dietary supplement reduced serum phosphorus and increased serum bicarbonate values in cats with CKD. In turn, this supplement could be used as a support therapy in cats with advanced CKD improving their clinical conditions without any adverse reaction. Finally, it is important to underline that all the animals completed the study and the owners reported a good palatability of the feed supplement.

Effects of weight loss with a moderate-protein, high-fiber diet on body composition, voluntary physical activity, and fecal microbiota of obese cats.

OBJECTIVE To determine effects of restriction feeding of a moderate-protein, high-fiber diet on loss of body weight (BW), voluntary physical activity, body composition, and fecal microbiota of overweight cats. ANIMALS 8 neutered male adult cats. PROCEDURES After BW maintenance for 4 weeks (week 0 = last week of baseline period), cats were fed to lose approximately 1.5% of BW/wk for 18 weeks. Food intake (daily), BW (twice per week), body condition score (weekly), body composition (every 4 weeks), serum biochemical analysis (weeks 0, 1, 2, 4, 8, 12, and 16), physical activity (every 6 weeks), and fecal microbiota (weeks 0, 1, 2, 4, 8, 12, and 16) were assessed. RESULTS BW, body condition score, serum triglyceride concentration, and body fat mass and percentage decreased significantly over time. Lean mass decreased significantly at weeks 12 and 16. Energy required to maintain BW was 14% less than National Research Council estimates for overweight cats and 16% more than resting energy requirement estimates. Energy required for weight loss was 11% more, 6% less, and 16% less than American Animal Hospital Association recommendations for weight loss (80% of resting energy requirement) at weeks 1 through 4, 5 through 8, and 9 through 18, respectively. Relative abundance of Actinobacteria increased and Bacteroidetes decreased with weight loss. CONCLUSIONS AND CLINICAL RELEVANCE Restricted feeding of a moderate-protein, high-fiber diet appeared to be a safe and effective means for weight loss in cats. Energy requirements for neutered cats may be overestimated and should be reconsidered.