In 2015, 65% of US households owned a pet, and 42.9% of US households owned a cat.1 Unfortunately, there is an increasing incidence of obesity in companion animals in the United States, and obesity currently is considered the most common nutritional disorder in pets.2 Data from a 2014 survey conducted by the Association for Pet Obesity Prevention3 revealed that 57.9% of US cats (approx 55 million cats) are overweight (29.8%) or obese (28.1%). To further complicate the issue, there is a fat gap that inhibits owners from recognizing the degree to which their pets are overweight.4,5 A general classification defines an overweight cat as one that weighs 10% to 20% over its ideal BW and an obese cat as one that weighs > 20% over its ideal BW.6 Each unit increase in BCS above ideal (ideal BCS is 5 on a scale of 1 to 9) represents approximately 10% to 15% over ideal BW.7,8
Obesity in cats is associated with numerous metabolic abnormalities (eg, hyperlipidemia and glucose intolerance), endocrinopathies (eg, diabetes mellitus), skeletal stress, exercise intolerance, and many other detrimental effects on health, most of which are reversible with weight loss.2 Obesity develops as a result of a positive imbalance between energy intake and energy expenditure.2 Aspects of domestication and humanization of pets also contribute to obesity. These risk factors include neutering,4,5,9 decreased amounts of physical activity, increased food intake, and access to highly palatable high-fat or energy-dense diets.10–12 Although prevention of obesity would ideally avoid these conditions, it is necessary to develop effective and safe methods for treatment of obesity to improve health status. The recommendation for safe weight loss for cats is 1% to 1.5% of BW/wk.13 To safely avoid inducing hepatic lipidosis during weight loss, it is generally recommended that cats should eat at least 50% of their MER.6 However, experiments and clinical trials have included caloric restrictions between 59% and 80% of MER without evidence of hepatic lipidosis.14,15
The feline gastrointestinal tract has a vast and diverse microbiota population, with the body containing as many (or more) bacteria than it does host cells.16 The community structure and function of the gastrointestinal microbiota (ie, gut microbiota) are influenced by diet through utilization of host nutrients and production of metabolites for uptake, which can promote both health and disease. Gut microbiota dysbiosis has been associated with obesity and is known to promote adiposity and influence peripheral organ function by altering satiety signals in the brain, hormone regulation in the gastrointestinal tract, and metabolism of lipids in the adipose tissue, liver, and muscle.17 Microbes may also affect energy harvest, influence intestinal permeability, or increase local or systemic inflammation, which can be associated with obesity and insulin resistance.18 Most of the studies have been conducted with humans or rodents. Although gut microbiota populations have been characterized in cats, to our knowledge, the gut microbiota of cats during weight loss have not been evaluated.
The objective of the study reported here was to determine the effects of weight loss on body composition, voluntary physical activity, and fecal microbiota populations of overweight cats during consumption of a moderate-protein, high-fiber diet. We hypothesized that closely monitoring BW and adjusting feed intake accordingly would lead to steady weight loss and would increase fat loss while maintaining lean mass. In previous studies,19,20 weight gain was accompanied by a reduction in voluntary physical activity. Therefore, we hypothesized that the reverse would be true for weight loss in the cats of this study (ie, an increase in voluntary physical activity). Finally, we hypothesized that weight loss would reduce blood lipid concentrations, result in serum biochemical values within or close to reference ranges, and alter the fecal microbiota community (eg, increases in Bifidobacterium spp, Lactobacillus spp, and Faecalibacterium spp and decreases in Desulfovibrio spp).
This manuscript represents a portion of a thesis submitted by Ms. Pallotto to the Division of Nutritional Sciences, College of Agricultural, Consumer and Environmental Sciences, University of Illinois, Urbana, Ill, as partial fulfillment of the requirements for a Master of Science degree.
Supported in part by The Nutro Company.
Presented in abstract form at the 15th Annual American Academy of Veterinary Nutrition Clinical Nutrition and Research Symposium, Indianapolis, June 2015.
Association of Official Analytical Chemists
Body condition score
Dual-energy x-ray absorptiometry
Maintenance energy requirement
The Nutro Company, Franklin, Tenn.
Wiley mill, model 4, Thomas Scientific, Swedesboro, NJ.
Leco nitrogen/protein determinator, model FP-2000, Leco Corp, St Joseph, Mich.
Oxygen bomb calorimeter, model 1261, Parr Instruments Co, Moline, Ill.
Actical physical activity monitor, Mini Mitter Co, Bend, Ore.
Actical physical activity software, Mini Mitter Co, Bend, Ore.
Hologic model QDR-4500 fan beam x-ray bone densitometer, Hologic Inc, Waltham, Mass.
BD vacutainer serum separator tubes, BD Medical Technology, Franklin Lakes, NJ.
Hitachi 911 clinical chemistry analyzer, Roche Diagnostics, Palo Alto, Calif.
Veterinary Medicine Diagnostics Laboratory, College of Veterinary Medicine, University of Illinois, Urbana, Ill.
MO BIO PowerSoil kit, MO BIO Laboratories, Carlsbad, Calif.
Qubit 3.0 fluorometer, Life Technologies, Grand Island, NY.
E-Gel EX gel 1%, Invitrogen, Grand Island, NY.
MiSeq2000, Illumina Inc, San Diego, Calif.
QIIME (Quantitative Insights Into Microbial Ecology) software, version 1.8.0. Available at: qiime.org. Accessed May 22, 2015.
Greengenes 13_8 database, The Greengenes Database Consortium. Available at: greengenes.secondgenome.com. Accessed May 22, 2015.
PROC MIXED, SAS, version 9.3, SAS Institute Inc, Cary, NC.
Nguyen P, Dumon H, Frenais R, et al. Energy expenditure and requirement assessed using three different methods in adult cats (abstr), in Proceedings. Compend Contin Educ Vet 2001;23:86S.
Trippany JR, Funk J, Buffington CT. Effects of environmental enrichments on weight loss in cats (abstr). J Vet Intern Med 2003;17:430.
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