Effects of Weight Loss and Moderate-Protein, High-Fiber Diet Consumption on the Fasted Serum Metabolome of Cats

Metabolomic profiling of serum alterations and biomarker discovery in feline hepatic liposis

Feline hepatic lipidosis (FHL) is a common liver dysfunction caused by metabolic disorders. The objective was to evaluate the metabolic alteration in the cats of FHL and to identify biomarkers that can serve as biomarker for FHL. Differential metabolites in the serum of spontaneous FHL cats (FS, n = 12) and healthy cats (CS group, n = 12) were analyzed using GC/MS metabolomics. Differential metabolites with diagnostic significance were identified through receiver operating characteristic (ROC) curves. The expression level of the differential metabolite 2-hydroxybutyric acid (2-HB) was detected in the serum of the FS and CS groups, and biomarker were established. The biomarker efficacy of 2-HB for FHL was verified using serum samples from cats with FHL caused by different etiologies (F, n = 10) and healthy cats (C, n = 50). There were 13 significantly different metabolites between the CS and FS groups (VIP > 1, P < 0.05) with the area under the ROC curve (AUC) greater than 0.70. The AUC for serum 2-HB was 0.90 (95% confidence interval 0.767-1.000, P < 0.001), with an optimal critical value of 564.8 ng/L. By randomly detecting serum 2-HB in groups F and C (the optimal cut-off value is 564.8 ng/L), the detection rate for FHL diagnosis was 100% and the false positive rate was 0%. In cats with FHL, metabolic changes occur in amino acids, nucleotide sugars, glycerophospholipids, phenylalanine, galactose, alpha-linolenic acid, and glycerides. A serum 2-HB level greater than 564.8 ng/L serves as a biomarker for FHL.

Evidence of obesity-induced inflammatory changes in client-owned cats

Background and Aim

Insulin resistance and type 2 diabetes mellitus are common health issues in obese (OB) cats. In humans, obesity leads to alterations in adipokine and proinflammatory cytokine secretion, causing persistent inflammation. The inflammatory impact of obesity in cats remains unproven. This study investigated associations between obesity and inflammatory and metabolic changes in three groups of client-owned Brazilian domestic shorthair cats: naturally lean, overweight (OW), and OB.

Materials and Methods

Cats from the Veterinary Hospital of Professor Sylvio Barbosa e Cardoso (FAVET/UECE) were clinically evaluated. Blood samples were collected for hematological and biochemical profile measurements, and part of the serum was used for measuring adipokine and inflammatory cytokines using sandwich enzyme-linked immunosorbent assay.

Results

In both the OW and OB groups, serum cholesterol and insulin concentrations increased, while triglyceride concentrations were notably elevated in the OB group. In the OW and OB groups, serum adiponectin, tumor necrosis factor-α, and interleukin-1β levels were elevated, and leptin levels were significantly higher in the OB group.

Conclusion

This study is the first in Brazil to reveal increased serum levels of inflammatory markers in OW and OB client-owned felines. OW cats exhibited higher proinflammatory marker levels, implying obesity-induced inflammation.

Description of the fasted serum metabolomic signature of lean and obese cats at maintenance and of obese cats under energy restriction

This study aimed to investigate the serum metabolomic profile of obese and lean cats as well as obese cats before and after energy restriction for weight loss. Thirty cats, 16 obese (body condition score 8 to 9/9) and 14 lean (body condition score 4 to 5/9), were fed a veterinary weight loss food during a 4-week period of weight maintenance (L-MAINT and O-MAINT). The 16 obese cats were then energy restricted by a 60% energy intake reduction with the same food for a 10-week period (O-RESTRICT). Fasted serum metabolites were measured using nuclear magnetic resonance and direct infusion mass spectrometry after the maintenance period for L-MAINT and O-MAINT cats and after the energy restriction period for O-RESTRICT and compared between groups using a two-sided t-test. Obese cats lost 672 g ± 303 g over the 10-week restriction period, representing a weight loss rate of 0.94 ± 0.28% per week. Glycine, l-alanine, l-histidine, l-glutamine, 2-hydroxybutyrate, isobutryric acid, citric acid, creatine, and methanol were greater in O-RESTRICT compared to O-MAINT. There was a greater concentration of long-chain acylcarnitines in O-RESTRICT compared to both O-MAINT and L-MAINT, and greater total amino acids compared to O-MAINT. Glycerol and 3-hydroxybutyric acid were greater in O-MAINT compared to L-MAINT, as were several lysophosphatidylcholines. Thus, energy restriction resulted in increased dispensable amino acids in feline serum which could indicate alterations in amino acid partitioning. An increase in lipolysis was not evident, though greater circulating acylcarnitines were observed, suggesting that fatty acid oxidation rates may have been greater under calorie restriction. More research is needed to elucidate energy metabolism and substrate utilization, specifically fatty acid oxidation and methyl status, during energy restriction in strict carnivorous cats to optimize weight loss.

Restricted feeding of weight control diets induces weight loss and affects body composition, voluntary physical activity, blood metabolites, hormones, and oxidative stress markers, and fecal metabolites and microbiota of obese cats

Feline obesity puts many cats at risk for comorbidities such as hepatic lipidosis, diabetes mellitus, urinary tract diseases, and others. Restricted feeding of specially formulated diets may improve feline health and safely support weight loss while maintaining lean mass. The objective of this study was to determine the effects of restricted intake of weight control diets on weight loss, body composition, voluntary physical activity, serum metabolic and inflammatory markers, and fecal metabolites and microbiota of obese cats. Twenty-four obese adult domestic shorthair cats [body weight (BW) = 5.51 ± 0.92 kg; body condition score (BCS) = 8.44 ± 0.53] were used. A leading grocery brand diet was fed during a 4-wk baseline to identify intake needed to maintain BW. After baseline (week 0), cats were allotted to one of 2 weight control diets (DRY or CAN) and fed to lose 1.5% BW per week for 18 wk. At baseline and 6, 12, 18 wk after weight loss, dual-energy x-ray absorptiometry scans were performed, blood and fecal samples were collected, and voluntary physical activity was measured. Change from baseline data was analyzed statistically using the Mixed Models procedure of SAS, with P < 0.05 being significant and P < 0.10 being trends. BW was reduced by 1.54 ± 0.51% per week. Restricted feeding of both diets led to BW (P < 0.01) and fat mass loss (P < 0.01), reduced BCS (P < 0.01), reduced leptin (P < 0.01) and insulin (P < 0.01) concentrations, and increased superoxide dismutase (P < 0.01) and active ghrelin (P < 0.01) concentrations. Change from baseline fecal scores was reduced (P < 0.01) with restricted feeding and weight loss, while total short-chain fatty acid, acetate, and propionate concentration reductions were greater (P < 0.05) in cats fed CAN than those fed DRY. Fecal bacterial alpha diversity measures increased (P < 0.01) with restricted feeding and weight loss. Fecal bacterial beta diversity was altered by time in all cats, with week 0 being different (P < 0.05) than weeks 6, 12, and 18. Change from baseline relative abundances of 3 fecal bacterial phyla and over 30 fecal bacterial genera were impacted (P < 0.05) or tended to be impacted (P < 0.10) by dietary treatment. Our data demonstrate that restricted feeding of both weight control diets was an effective means for weight loss in obese adult domestic cats. Some changes were also impacted by diet, highlighting the importance of diet formulation and format, and nutrient composition in weight control diets.

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 Serum and Fecal Metabolomic Profiles of Growing Kittens Treated with Amoxicillin/Clavulanic Acid or Doxycycline

Simple Summary

This study investigated the impact of antibiotic treatment οn the serum and fecal metabolome (the collection of all small molecules produced by the gut bacteria and the host) of young cats. Thirty 2-month-old cats with an upper respiratory tract infection were treated with either amoxicillin/clavulanic acid for 20 days or doxycycline for 28 days. In addition, another 15 control cats that did not receive antibiotics were included. Blood was collected on days 0 (before treatment), 20/28 (last day of treatment), and 300 (10 months after the end of treatment), while feces were collected on days 0, 20/28, 60, 120, and 300. Seven serum and fecal metabolites differed between cats treated with antibiotics and control cats at the end of treatment period. Ten months after treatment, no metabolites differed from healthy cats, suggesting that amoxicillin/clavulanic acid or doxycycline treatment only temporarily affects the abundance of the serum and fecal metabolome.

Abstract

The long-term impact of antibiotics on the serum and fecal metabolome of kittens has not yet been investigated. Therefore, the objective of this study was to evaluate the serum and fecal metabolome of kittens with an upper respiratory tract infection (URTI) before, during, and after antibiotic treatment and compare it with that of healthy control cats. Thirty 2-month-old cats with a URTI were randomly assigned to receive either amoxicillin/clavulanic acid for 20 days or doxycycline for 28 days, and 15 cats of similar age were enrolled as controls. Fecal samples were collected on days 0, 20/28, 60, 120, and 300, while serum was collected on days 0, 20/28, and 300. Untargeted and targeted metabolomic analyses were performed on both serum and fecal samples. Seven metabolites differed significantly in antibiotic-treated cats compared to controls on day 20/28, with two differing on day 60, and two on day 120. Alterations in the pattern of serum amino acids, antioxidants, purines, and pyrimidines, as well as fecal bile acids, sterols, and fatty acids, were observed in antibiotic-treated groups that were not observed in control cats. However, the alterations caused by either amoxicillin/clavulanic acid or doxycycline of the fecal and serum metabolome were only temporary and were resolved by 10 months after their withdrawal.