Neutered Male Cats Research Articles

308 Isoenergetic reduction of dietary macronutrients reveals distinct fecal metabolomic signatures in lean and obese cats fed at maintenance

Abstract Obesity has become a concerning problem in cats. Increasing evidence demonstrates the utility of metabolomics in identifying disease biomarkers and assessing the effects of nutritional interventions, although limited information exists regarding alterations in fecal metabolites in lean and obese domestic cats in response to different macronutrient content. In the current study, three extruded diets were formulated based on adult maintenance using an isoenergentic approach. These diets were created by adjusting the levels of identical ingredients to achieve a low-protein [LP; protein 28% metabolizable energy (ME), fat 40%ME, NFE 32% ME), a low-fat (LF; protein 42% ME, fat 30% ME, NFE 30% ME), and a low-carbohydrate (LC; protein 36% ME, fat 41% ME, NFE 23% ME] diet. Healthy neutered male adult cats [n = 18; body condition scores (BCS) 4 or 5 (lean, n = 9) and 8 or 9 (obese, n = 9)] were fed each diet for a period of 4 wk in a 3 x 3 Latin square design. Fecal samples from each cat were collected between d 22 and 28 of each treatment period. A total of 67 fecal metabolites in six groups (35 amino acids, 11 fatty acids, 10 sugars and sugar metabolites, 5 alcohols, 3 nitrogenous bases, and 3 others) were analyzed using 1H NMR spectroscopy. To evaluate the impact of body condition, diet and their interaction on each metabolite, proc GLIMMIX covariance structure was selected by the smallest Akaike information criterion value in SAS. The Shapiro-Wilk test was used to check normality and lognormal or beta distribution were applied when appropriate. Bonferroni correction post-hoc test was followed to correct Type I error. Statistical significance was considered at P < 0.05. In lean cats, significantly greater concentrations of fecal proteinogenic and branched-chain amino acids, such as methionine, valine, and L-lysine, as well as pyruvic acid and sugars (P < 0.05) were observed. This suggests that these metabolites may either be more actively fermented by bacteria or not utilized as extensively as in obese cats, potentially contributing to a reduction in obesity status. Regardless of body condition, there is a possibility of an enhanced activity in the tryptophan degradation pathway, leading to the greatest concentrations of fecal tryptophan (P = 0.04) in the LF diet, while the greatest fecal D-galactose (P = 0.04) in the LP diet was likely due to the greater dietary carbohydrate content. These observed results suggested that fecal metabolites were influenced by both body condition and diet; however, body condition had a more substantial impact on metabolite changes in cats, whereas no body condition and diet interaction were noted. Overall, the study indicated distinct fecal metabolic signatures in lean and obese cats subjected to different macronutrient diets and further research is warranted to validate the observed findings. Funding was provided by Champion Petfoods, Natural Sciences and Engineering Council of Canada and Mitacs Accelerate.

502 Cat and mouse: The effect of consuming four different diet formants (intact mice, raw, canned wet and kibble) on energy expended to consume a meal and immediately post-prandial in domestic cats

Abstract Cats are obligate carnivores; however, we feed them a variety of different diet formats without a clear understanding of feeding behavior and metabolism among diet formats. Whole-prey or raw diets may mimic a more natural diet and require more energy to consume. However, there is currently a dearth of literature examining feline energy expenditure (EE) during the consumption of and immediate post-prandial period when fed different diet formats. The present study aimed to investigate differences in the energetics of adult cats consuming four different diet formats in isocaloric offerings: raw intact mice, commercial raw, canned wet, and kibble diets. Adult neutered male cats [n = 12; body weight (BW) = 4.82 ± 0.164 kg) were used in a 4 x 4 replicated Latin square design and adapted to consuming each diet format before the initiation of the study. Following a 2-d adaptation period, cats were fed 25% of their daily caloric requirement (50.77 ± 1.549 kcal) in indirect calorimetry chambers in which VO2 and VCO2 exchange were measured. Energy expenditure (kcal/BW0.67 kg) was calculated for the consumption period, 15 min immediately post-prandial and 2 h post-prandial. Respiratory gases were measured for one fasted reading, followed by the first feeding. During each feeding, measurements were taken during the consumption period and 15 min post-prandial. For the following 2 h, respiratory gases were measured every 25 min for an additional 4 measures of respiratory gases. All data were analyzed using a generalized linear mixed model considering the effects of treatment, time and their interaction as fixed, and the effects of cat and period as random. A spatial power covariance structure was used to model repeated measures. Significance was considered at P < 0.05 and Tukey’s post-hoc test was performed to separate means. Energy expenditure during consumption and 15 min post-prandial was similar among treatments, and EE for 15 min post-prandial was greater than EE during consumption (P < 0.001). During the 2 h post-prandial, EE for the mice diet was greater than the kibble and canned wet diets (P < 0.001), while EE for the raw diet was only greater than the kibble diet (P < 0.001). Energy expenditure was similar between the kibble and canned wet diets (P = 0.919) and between the mice and raw diets (P = 0.598). Among all treatments and time periods, the mouse diet had the greatest mean EE. An increase in EE during the feeding period and post-prandial could benefit sedentary indoor cats who may be in positive energy balance. Feeding cats a naturalistic diet, such as intact mice or a raw diet, may increase activity levels and EE, but the longer-term effects of these feeding formats on energy balance need to be explored.

291 Isoenergetic reduction of dietary macronutrients changes body composition and physical activity in cats, regardless of body condition, when fed to maintenance

Abstract Commercial extruded cat foods deviate noticeably from the natural diet of wild cats and contain greater carbohydrate and less protein. This alteration in macronutrient distribution is postulated as a potential factor in feline obesity, yet the precise role of carbohydrates in either predisposing to, or treating, obesity in cats remains inconclusive. This study explored the effects of diets differing in protein, fat, and carbohydrates (NFE) on physical activity and body composition when fed to adult male cats to maintain body weight (BW). Three extruded diets were formulated for adult maintenance according to AAFCO in an isoenergetic approach using the same ingredients in varying proportions: low-protein (LP; protein 28% of metabolizable energy [ME], fat 40% ME, NFE 32% ME), low-fat (LF; protein 42% ME, fat 30% ME, NFE 30% ME), or low-carbohydrate (LC; protein 36% ME, fat 41%ME, NFE 23% ME). Lean (n = 9) and obese (n = 9) adult male neutered cats were fed each diet for 4-wk in a 3 x 3 Latin square design. Physical activity was measured via actigraphy on d 15 to 21 of each period. On d 23 total tissue mass (TTM), body fat mass (BFM), lean soft tissue mass (LSTM), and bone mineral content (BMC) were assessed by dual energy x-ray absorptiometry. Daily food intake and weekly BW were recorded. Data were statistically analyzed in SAS Studio via the GLIMMIX procedure with diet and body condition (bc) as fixed effects and cat as subject. A Tukey post-hoc analysis was performed to assess multiple comparisons when significant (P < 0.05). Body weight (Pbc < 0.0001), TTM (Pbc < 0.0001), BFM (Pbc < 0.0001), LSTM (Pbc < 0.0001), and BMC (Pbc = 0.004) were greater in obese compared with lean cats. Regardless of body condition, LSTM was greater in cats consuming the LF diet (P = 0.010). Daily physical activity was similar between lean and obese cats; however, activity as a ratio of light:dark activity was greater for lean cats compared with obese (Pbc = 0.027). Additionally, cats were more active during dark hours when fed LC and LF (Pdiet = 0.016), though no difference was observed for activity during light hours (P = 0.452). These findings support previous observations regarding body composition disparities between lean and obese cats. Contrary to previous reports, no discernible distinctions in voluntary physical activity were noted between lean and obese cats. In previous studies, both high-carbohydrate and high-fat diets reduced voluntary physical activity when fed to maintain BW which was attributed to a potential alteration in mood and energy levels seen in other species. An increase in physical activity in cats consuming the LF diet could suggest a similar pattern. Future research should explore the metabolic implications of varied macronutrient distributions to expand upon the physiological insights presented herein. Funding for this study was provided by Champion Petfoods, Mitacs Accelerate, and the Natural Sciences and Engineering Council of Canada.

Correlation, agreement and concordance of cardiac output estimated by transthoracic ultrasound and transesophageal Doppler with pulmonary artery thermodilution in anesthetized cats

ObjectiveTo characterize the correlation, agreement and concordance of cardiac output (CO) measured with transthoracic ultrasound and the correlation and concordance of aortic blood flow (ABF) minute distance (MD) measured by transesophageal Doppler with CO measured by pulmonary artery thermodilution (PATD) in cats. Study designExperimental study. AnimalsA group of six healthy male neutered cats, aged 2–8 years and weighing 5.3 ± 0.3 kg. MethodsCats were anesthetized with isoflurane in oxygen. CO was measured by PATD (COPATD) and transthoracic echocardiography (COECHO). ABF MD was measured using an esophageal Doppler flow probe aligned with descending ABF. All measurements were made under three conditions: dexmedetomidine (20 μg kg–1) intravenously; atipamezole (200 μg kg–1) intramuscularly and atropine (20 μg kg–1) intravenously as needed to achieve a minimum heart rate of 140 beats minute–1; and dopamine (20 μg kg–1 minute–1) intravenously in that order. Correlation between COPATD and COECHO, and COPATD and Doppler MD was evaluated using repeated measures correlation. Agreement between COPATD and COECHO was evaluated using Bland–Altman method. Differences between consecutive pairs of CO measurements were calculated for concordance analysis. ResultsCorrelation between COPATD and COECHO and between COPATD and MD was significant (p < 0.001), with correlation coefficients greater than 0.92. A bias of > 27% and upper limits of agreement of 66% were found between COPATD and COECHO. Concordance rate with COPATD was 76–80% for COECHO and 72% for MD. Conclusions and clinical relevanceEchocardiographic methods for the measurement of CO showed poor agreement and concordance with PATD. MD showed poor concordance with PATD. As such, these methods cannot be used as an alternative to PATD nor can they appropriately track changes in CO in anesthetized cats.

Minimum methionine requirement in adult cats as determined by indicator amino acid oxidation.

There is a lack of empirical data on the dietary Met requirement, in the presence of Cys or cystine, in adult cats. Thus, the aim of this study was to determine the Met requirement, in the presence of excess Cys, in adult cats at maintenance using the indicator amino acid oxidation (IAAO) technique. Six adult neutered male cats were initially selected and started the study. Cats were adapted to the basal diet sufficient in Met (0.24% dry matter, DM) for 14 d prior to being randomly allocated to one of eight dietary levels of Met (0.10%, 0.13%, 0.17%, 0.22%, 0.27%, 0.33%, 0.38%, and 0.43% DM). Different dietary Met concentrations were achieved by supplementing the basal diet with Met solutions. Alanine was additionally included in the solutions to produce isonitrogenous and isoenergetic diets. Cats underwent a 2-d adaptation period to each experimental diet prior to each IAAO study day. On IAAO study days, 13 meals were offered corresponding to 75% of each cat's daily food allowance. The remaining 25% of their daily food intake was offered after each IAAO study. A bolus dose of NaH13CO3 (0.44mg kg-1) and l-[1-13C]-phenylalanine (13C-Phe; 4.8mg kg-1) were provided in fifth and sixth meals, respectively, followed by a constant dose of 13C-Phe (1.04mg kg-1) in the next meals. Breath samples were collected and total production of 13CO2 was measured every 25min through respiration calorimetry chambers. Steady state of 13CO2 achieved over at least three breath collections was used to calculate oxidation of 13C-Phe (F13CO2). Competing models were applied using the NLMIXED procedure in SAS to determine the effects of dietary Met on 13CO2. Two cats were removed from the study as they did not eat all meals, which is required to achieve isotopic steady. A breakpoint for the mean Met requirement, with excess of Cys, was identified at 0.24% DM (22.63mg kg-1) with an upper 95% confidence limit of 0.40% DM (37.71 mg·kg-1), on an energy density of 4,164 kcal of metabolizable energy/kg DM calculated using the modified Atwater factors. The estimated Met requirement, in the presence of excess of Cys, is higher than the current recommendations proposed by the National Research Council's Nutrient Requirement of Dogs and Cats, the Association of American Feed Control Officials, and the European Pet Food Industry Federation.

Alfaxalone increases measured progesterone concentration in neutered male cats when determined by immunoreactivity.

Alfaxalone is a commonly used anesthetic agent in small animals. In cats, alfaxalone can be administered as an IM agent to achieve clinically useful sedation or anesthesia, negating the need for IV injection in difficult patients. The molecular structure of alfaxalone is similar to the hormone progesterone (P4). It is hypothesized that alfaxalone would cross-react with the assay measuring progesterone causing a false elevation. 8 healthy neutered male, domestic shorthair cats that were privately owned were enrolled in the study. Male neutered cats were administered 3 mg/kg of alfaxalone IM. Blood samples were collected at set time points (baseline, 30 minutes, 60 minutes, 3 hours, 6 hours, and 10 hours after administration), and serum concentrations of progesterone immunoreactivity (IR) were determined using the Siemens Immulite 1000 automated immunoassay system. Statistical analysis was performed with repeated measures ANOVA and a Tukey-Cramer multiple comparisons test. A P value of < .05 was used for significance. Serum progesterone IR was significantly elevated at 30 minutes, 1 hour, and 3 hours (P < .05) when compared to baseline progesterone immunoreactivity. Progesterone immunoreactivity had returned to baseline by 6 hours. This study suggests that alfaxalone administered IM in cats may interfere with immunoassay measurement of serum progesterone for up to 6 hours. Caution should be used when interpreting serum progesterone immunoreactivity results in cats within 4 hours of alfaxalone.

195 Restricted Feeding and Weight Loss Change Fecal Metabolite Concentrations and Microbiota Populations of Overweight Cats

Abstract Feline obesity negatively influences many metabolic processes, health outcomes, and the individual well-being of cats, but little research evaluates the modification in gastrointestinal microbiota in an overweight state. The use of specially formulated diets and restricted feeding, resulting in subsequent body weight (BW) loss, may be used to improve health and modify gastrointestinal microbiota of overweight cats. This study aimed to identify and determine the effects of restricted feeding and BW loss on fecal metabolite concentrations and microbiota populations of overweight cats. All procedures were approved by the University of Illinois IACUC before experimentation. Twenty-two overweight adult spayed female and neutered male cats [BW = 5.70 ± 1.0 kg; BCS = 7.68±0.6; age = 4 ± 0.4 yr] were used in a 24-wk BW loss study. A control diet (OR) was fed during a 4-wk baseline to identify intake needed to maintain BW. After baseline (wk 0), cats were allotted to OR or a BW loss diet (FT) and fed to lose ~1.0% BW/wk. Fecal samples were collected at baseline (wk 0), and weeks 4, 8, 12, 16, 20, and 24 for microbiota and metabolite analyses. Fecal microbiota data were analyzed and evaluated using QIIME2 and Mixed Models procedure of SAS, with P &amp;lt; 0.05 considered significant. Change from baseline fecal acetate, propionate, butyrate, total short-chain fatty acid, isobutyrate, valerate, phenol, indole, and total phenol and indole concentrations were reduced (P &amp;lt; 0.05) with restricted feeding and BW loss. Change from baseline fecal scores and valerate concentrations were also affected by diet, with greater (P &amp;lt; 0.05) reductions occurring in cats fed OR than those fed FT. Change from baseline fecal pH was also greater (P = 0.05) in cats fed OR than those fed FT. Fecal bacterial alpha diversity was not affected by diet or restricted feeding and BW loss. However, fecal bacterial beta diversity, assessed by weighted and unweighted UniFrac distances and presented as principal coordinate plots, showed separation between dietary groups, with some significant clustering as a result of restricted feeding and weight loss. The relative abundances of a single fecal bacterial phylum and 5 fecal bacterial genera were impacted by restricted feeding and weight loss. Diet had a greater effect, with 3 fecal bacterial phyla and 19 fecal bacterial genera being different (P &amp;lt; 0.05) between dietary treatment groups. Our data demonstrate that restricted feeding of specially formulated diets, and subsequent BW loss, modifies the fecal metabolite profiles and microbiota populations of overweight cats. The mechanisms by which these changes may affect feline gastrointestinal health and metabolism requires further study.

Dietary choline, but not L-carnitine, increases circulating lipid and lipoprotein concentrations, without affecting body composition, energy expenditure or respiratory quotient in lean and obese male cats during weight maintenance.

Due to the involvement in one-carbon metabolism and lipid mobilization, choline and L-carnitine supplementation have been recommended to minimize hepatic lipid accumulation and support fat oxidation, respectively. This study investigated the lipotropic benefits of choline or L-carnitine supplementation in lean and obese cats maintaining body weight (BW). Lean [n = 9; body condition score (BCS): 4-5/9] and obese (n = 9; BCS: 8-9/9) adult male neutered colony cats were used in a replicated 3 x 3 complete Latin square design. Treatments included choline (378 mg/kg BW0.67), L-carnitine (200 mg/kg BW) and control (no supplement). Treatments were supplemented to the food for 6 weeks each, with a 2-week washout between treatments. Cats were fed once daily to maintenance energy requirements, and BW and BCS were assessed weekly. Fasted blood collection, indirect calorimetry, and dual-energy X-ray absorptiometry occurred at the end of each treatment period. Serum was analyzed for cholesterol (CHOL), high-density lipoprotein CHOL (HDL-C), triglycerides (TAG), non-esterified fatty acids (NEFA), glucose, creatinine (CREAT), urea, alkaline phosphatase (ALP) and alanine aminotransferase (ALT). Very low-density lipoprotein CHOL (VLDL) and low-density lipoprotein CHOL (LDL-C) were calculated. Data were analyzed using proc GLIMMIX, with group and period as random effects, and treatment, body condition, and their interaction as fixed effects, followed by a Tukey's post-hoc test when significance occurred. Cats supplemented choline had lower food intake (P = 0.025). Treatment did not change BW, BCS and body composition (P > 0.05). Obese cats had greater ALP, TAG, and VLDL, and lower HDL-C compared to lean cats (P < 0.05). Choline resulted in greater CHOL, HDL-C, LDL-C and ALT (P < 0.05). L-carnitine resulted in lower CREAT (P = 0.010). Following the post-hoc test, differences between treatment means were not present for ALP (P = 0.042). No differences were found for glucose, urea or NEFA (P > 0.05). Obese cats had a lower fed respiratory quotient (RQ), regardless of treatment (P = 0.045). Treatment did not affect fed or fasted RQ and energy expenditure (P > 0.05). Choline appeared to increase circulating lipid and lipoprotein concentrations regardless of body condition, likely through enhanced lipid mobilization and hepatic elimination. Neither dietary choline or L-carnitine altered body composition or energy metabolism in the lean or obese cats, as compared to control.

Clinical Characterisation of Caudal Traumatic Malocclusions and Treatment Outcomes in Cats (2018-2022).

Caudal malocclusions in cats may result in a variety of traumatic lesions affecting the soft tissues of the ipsilateral mandible such as fovea, gingival cleft, and proliferative lesions. Fifty-one cats diagnosed with a traumatic caudal malocclusion were compared with a control hospital population and evaluated for prevalence with respect to breed and sex. Twenty-two cats that were treated had radiographic, clinical findings, and the outcome of treatment (extraction or odontoplasty) recorded. Maine Coon, Persian, and male neutered cats were overrepresented while Domestic Shorthairs were underrepresented within the study population. Radiographically, 50% of the fovea lesions had an area of decreased bone density in the region of the lesion and none of these had evidence of periodontal disease. All gingival cleft lesions had radiographic changes consistent with periodontal disease. 15.4% of proliferative lesions presented with radiographic changes, with only half of those presenting with both radiographic and clinical evidence of periodontal disease. Eleven cats were treated by odontoplasty and eleven by extraction. One cat treated by odontoplasty developed new lesions caudally, and another had persistence of the initial lesions. Two cats in the extraction group developed new lesions rostral to the extracted teeth. In most instances, odontoplasty or extraction resulted in successful soft tissue lesion resolution. In rare cases, additional treatment was necessary due to either persistence or development of new lesions.

Successful management of minoxidil 5% toxicosis in 2 cats from the same household.

To describe the successful management of 2 cats following ingestion of minoxidil 5%. Two 2-year-old neutered male Savannah cats were presented following suspected minoxidil 5% ingestion. Both cats developed significant myocardial injury, and clinical signs were consistent with congestive heart failure, supported by cardiac troponin I concentrations, echocardiogram, and thoracic radiographs. They required vasopressor therapy and were decontaminated with intravenous lipid emulsion therapy. Following decontamination, both cats were successfully discontinued from vasopressor therapy, and their clinical signs resolved within 24hours. The cats were successfully discharged without long-lasting cardiac compromise. Their echocardiograms and cardiac troponin concentration 7weeks after discharge were within reference intervals. This is the first detailed report of the successful management of cats following minoxidil 5% ingestion.

Pharmacokinetics of buprenorphine and its metabolite norbuprenorphine in neutered male cats anesthetized with isoflurane

ObjectiveTo characterize the pharmacokinetics of buprenorphine and norbuprenorphine in isoflurane-anesthetized cats. Study designProspective experimental study. AnimalsA group of six healthy adult male neutered cats. MethodsCats were anesthetized with isoflurane in oxygen. Catheters were placed in a jugular vein for blood sampling and in a medial saphenous vein for buprenorphine and lactated Ringer’s solution administration. Buprenorphine hydrochloride (40 μg kg–1 over 5 minutes) was administered intravenously. Blood samples were collected before buprenorphine administration and at various times up to 12 hours after administration. Plasma buprenorphine and norbuprenorphine concentrations were measured using liquid chromatography/tandem mass spectrometry. Compartment models were fitted to the time-concentration data using nonlinear mixed effect (population) modeling. ResultsA five-compartment model (three compartments for buprenorphine and two compartments for norbuprenorphine) best fitted the data. Typical value (% interindividual variability) for the three buprenorphine volumes of distribution, and the metabolic clearance to norbuprenorphine, the remaining metabolic clearance and the two distribution clearances were 157 (33), 759 (34) and 1432 (43) mL kg–1, and 5.3 (33), 16.4 (11), 58.7 (27) and 6.0 (not estimated) mL minute–1 kg–1, respectively. Typical values (% interindividual variability) for the two norbuprenorphine volumes of distribution, and the norbuprenorphine metabolic and distribution clearances were 1437 (30) and 8428 (not estimated) mL kg–1 and 48.4 (68) and 235.9 (not estimated) mL minute–1 kg–1, respectively. Conclusions and clinical relevanceThe pharmacokinetics of buprenorphine in isoflurane-anesthetized cats were characterized by a medium clearance.

Effects of weight loss and feeding specially formulated diets on the body composition, blood metabolite profiles, voluntary physical activity, and fecal metabolites and microbiota of overweight cats.

Feline obesity is a common and preventable disease, posing a myriad of health risks and detriments. Specially formulated diets and restricted feeding may serve as an intervention strategy to promote weight loss and improve feline health. In this study, our objective was to determine the effects of restricted feeding and weight loss on body composition, voluntary physical activity, blood hormones and metabolites, and fecal microbiota of overweight cats. Twenty-two overweight adult spayed female and neutered male cats [body weight (BW) = 5.70 ± 1.0 kg; body condition score (BCS) = 7.68 ± 0.6; age = 4 ± 0.4 yr] were used in a weight loss study. A control diet (OR) was fed during a 4-wk baseline to identify intake needed to maintain BW. After baseline (week 0), cats were allotted to OR or a test diet (FT) and fed to lose ~1.0% BW/wk for 24 wk. At baseline and 6, 12, 18, and 24 wk after weight loss, dual-energy x-ray absorptiometry scans were performed and blood samples were collected. Voluntary physical activity was measured at weeks 0, 8, 16, and 24. Fecal samples were collected at weeks 0, 4, 8, 12, 16, 20, and 24. Change from baseline data were analyzed statistically using the Mixed Models procedure of SAS, with P < 0.05 considered significant. Restricted feeding of both diets led to weight and fat mass loss, lower BCS, and lower blood triglyceride and leptin concentrations. Cats fed the FT diet had a greater reduction in blood triglycerides and cholesterol than cats fed the OR diet. Restricted feeding and weight loss reduced fecal short-chain fatty acid, branched-chain fatty acid, phenol, and indole concentrations. Fecal valerate concentrations were affected by diet, with cats fed the OR diet having a greater reduction than those fed the FT diet. Fecal bacterial alpha diversity was not affected, but fecal bacterial beta diversity analysis showed clustering by diet. Restricted feeding and weight loss affected relative abundances of 7 fecal bacterial genera, while dietary intervention affected change from baseline relative abundances of 2 fecal bacterial phyla and 20 fecal bacterial genera. Our data demonstrate that restricted feeding promoted controlled and safe weight and fat loss, reduced blood lipids and leptin concentrations, and shifted fecal metabolites and microbiota. Some changes were also impacted by diet, highlighting the importance of ingredient and nutrient composition in weight loss diets.

106 Minimum Methionine Requirement in Adult Cats Using the Indicator Amino Acid Oxidation Technique

Abstract Despite the importance of Met for protein synthesis and a wide range of metabolic functions, little is known about its requirement in adult cats. Current recommendations for adult cats are based solely on studies using kittens and growth or nitrogen balance as the outcomes. Thus, this study aimed to determine the minimum Met requirement in mature cats using the indicator amino acid oxidation (IAAO) technique. Four adult neutered male cats (4.90 + 0.77 kg BW) were used in a Latin rectangle design. Cats were fed a semi-synthetic diet sufficient in Met for 2 weeks prior to being randomly allocated to one of the eight dietary Met treatments (0.12%, 0.17%, 0.21%, 0.28%, 0.35%, 0.42%, 0.50% and 0.57% dry-matter). Cys was provided in excess to spare the Met requirement and meet the Cys requirement. After 2d of adaptation, individual IAAO studies were performed. During each IAAO study day, cats were placed in indirect calorimetry chambers and fed 75% of their daily ration (12.38g/kg BW) split in 13 ½-hourly small meals. A priming dose of NaH13CO3 (0.44mg/kg) and L-[1-13C]-Phe (4.8mg/kg) were provided in the 4th and 5th meal, respectively, following by a constant dose (1.04mg/kg) of L-[1-13C]-Phe in the next meals. Breath samples were collected ½-hourly to measure 13CO2 enrichment to quantify 13CO2 and calculate F13CO2 during isotopic steady state (Phe oxidation). Competing models, broken-line linear (BLL) ascending model, and a broken-line quadratic (BLQ) ascending model, were fitted on F13CO2 to determine the minimum requirement of Met (breakpoint). The BLL yielded the best model with mean minimum Met requirement estimated at 0.305% (dry-matter), and the 95% confidence interval estimated at 0.521% (dry-matter) for adult cats. In conclusion, the estimated min Met requirement in this study is greater than those currently recommended by the NRC (2006; 0.17% dry-matter) and AAFCO (0.2% dry-matter).

Long-term follow up of 44 cats undergoing total hip replacement: Cases from a feline hip registry (2010-2020).

To report indications, complications, and long-term outcomes following feline total hip replacement (THR) using a client-based clinical metrology questionnaire, the Feline Musculoskeletal Pain Index (FMPI), and owner satisfaction. Multi-institutional retrospective cohort study. Cats (n=44) that underwent THR (n=56). Feline THRs submitted to a registry over a 10-year period were reviewed. The FMPI and owner satisfaction surveys were used to assess outcome. Forty-four cats met the inclusion criteria. Median age was 2 years (range: 0.9-11), and median bodyweight 5kg (range: 3.3-7.6). British Shorthair and Domestic Shorthair were the most frequent breeds. Most cats were neutered males (33/44) and slipped capital femoral epiphysis (SCFE) was the most common surgical indication (34/56). All implants were cemented micro and nano hip implants. Overall complications (11/56) included 9 major complications. The median duration of follow up was 752 days (range: 102-3089). No association was found between clinical variables and complications. The FMPI score improved from 0.111 (range: 0-1.222) to 2.111 (range: 0.888-3.666) postoperatively (P < .001). Owner satisfaction was reported as "very good" in 30/33 cases (90.9%). A validated client metrology questionnaire showed clinical improvement in cats following THR. The most common indication for THR in cats was SCFE occurring in young male neutered cats. Complication rates were comparable to previous reports. Total hip replacement appears to be a successful surgical treatment for feline hip disease with very good owner satisfaction and acceptable complication rates.

Dose-response relationship between dietary choline and serum lipid profile, energy expenditure, and respiratory quotient in overweight adult cats fed at maintenance energy requirements.

Choline is an essential nutrient linked to hepatic lipid metabolism in many animal species, including cats. The current study investigated the serum lipid profiles, serum liver enzymes, respiratory quotients, and energy expenditures of overweight cats fed maintenance diets, in response to graded doses of supplemental dietary choline. Overweight (body condition score [BCS]: ≥6/9) adult male neutered cats (n = 14) were supplemented with five choline chloride doses for 3-wk periods, in a 5 × 5 Latin square design. Doses were based on individual body weight (BW) and the daily recommended allowance (RA) for choline (63 mg/kg BW0.67) according to the National Research Council. Doses were control (no additional choline: 1.2 × RA, 77 mg/kg BW0.67), 2 × RA (126 mg/kg BW0.67), 4 × RA (252 mg/kg BW0.67), 6 × RA (378 mg/kg BW0.67), and 8 × RA (504 mg/kg BW0.67). Choline was top-dressed over the commercial extruded cat food (3,620 mg choline/kg diet), fed once a day at maintenance energy requirements (130 kcal/kgBW0.4). Body weight and BCS were assessed weekly. Fasted blood samples were taken and indirect calorimetry was performed at the end of each 3-wk period. Serum was analyzed for cholesterol, high-density lipoprotein cholesterol (HDL-C), triglycerides, non-esterified fatty acids, glucose, creatinine, blood urea nitrogen (BUN), alkaline phosphatase (ALP), and alanine aminotransferase. Very low-density lipoprotein cholesterol (VLDL) and low-density lipoprotein cholesterol were calculated. Data were analyzed via SAS using proc GLIMMIX, with group and period as the random effects, and treatment as the fixed effect. Statistical significance was considered at P < 0.05. Body weight and BCS did not change (P > 0.05). Serum cholesterol, HDL-C, triglycerides, and VLDL increased with 6 × RA (P < 0.05). Serum ALP decreased with 8 × RA (P = 0.004). Choline at 4 × and 6 × RA decreased serum BUN (P = 0.006). Fed or fasted respiratory quotient and energy expenditure did not differ among dietary choline doses (P > 0.05). These results suggest that dietary choline supplementation at 6 × RA may increase hepatic fat mobilization through increased lipoprotein transport and beneficially support hepatic health in overweight cats. Future studies that combine these results with existing knowledge of feline weight loss and hepatic lipidosis are warranted.

Feline uroliths: Analysis of frequency and epidemiology in Germany (2016-2020)

This study was aimed to assess the distribution and frequency of uroliths in cats as well as to evaluate gender-, age-, and breed-specific differences. 3629 uroliths from cats in Germany were analyzed by infrared-spectroscopy during the period 2016-2020. The majority (3300) of the uroliths originated from purebred cats of 22 breeds. Uroliths were prevalent in the order of male neutered (45.3 %), female spayed (35.3 %), male intact (7.4 %), and female intact cats (6.3 %). Median age of the cats with uroliths was 7 years, although it varied slightly depending on types of the urolith. The most frequent uroliths were calcium oxalate (59.5 %), followed by struvite (33.7 %), ammonium urate (2 %), calcium phosphate (1.7 %), cystine (0.7 %) and xanthine (0.4 %). Males (59.4 %) and females (59.2 %) showed nearly identical prevalence of calcium oxalates, whereas it significantly diverged in castrated (60.2 %) versus intact animals (54.4 %; p = 0.01). With regard to struvites, male cats (32.6 %) were less prone than females (35.4 %; p = 0.08) while intact cats (38.2 %) significantly outnumbered the castrated cohorts (33.1 %; p = 0.02). The prevalence for calcium oxalate uroliths increased by 6.6 % during the study period, contrasting a decrease of 5.5 % for struvites. Some breeds (> 10 individuals) showed significantly higher propensities than others for urolith formation. Calcium oxalates were significantly more frequent in British shorthair cats (85.2 %), Ragdoll (75 %), Scottish fold (74.1 %) and Persians (72.4 %). Struvites were prevailing in Norwegian forest cats (48.5 %), British longhair (41.7 %), European shorthair (41.7 %) and Siberian forest cats (36.8 %). Siamese cats had the significantly highest percentage of cystine uroliths (16 %). The occurrence of urine calculi in cats from Germany was found to be most frequent for calcium oxalate and struvite types. We also found breed-, age-, gender- specific differences in addition to variations depending on the neutering status of the animals.

Effect of intravenous butorphanol infusion on the minimum alveolar concentration of isoflurane in cats

ObjectiveTo determine the effect of butorphanol, administered by intravenous (IV) infusion, on the minimum alveolar concentration of isoflurane (MACISO) in cats and to examine the dosage dependence of this effect. Study designRandomized, placebo-controlled, crossover experimental study. AnimalsA group of six healthy adult male neutered cats. MethodsCats were anesthetized with isoflurane in oxygen. A venous catheter was placed for fluid and drug administration, and an arterial catheter was placed for measurement of arterial pressure and blood sampling. Four treatments were administered at random with at least 2 week interval between treatments: saline (control), butorphanol low dosage (treatment LD; 0.25 mg kg–1 IV bolus followed by 85 μg kg–1 minute–1 for 20 minutes, then 43 μg kg–1 minute–1 for 40 minutes, then 19 μg kg–1 minute–1), medium dosage (treatment MD, double the dosages in LD) and high dosage (treatment HD, quadruple the dosages in LD). MACISO was determined in duplicate using the bracketing technique and tail clamping. Pulse rate, arterial pressure, hemoglobin oxygen saturation, end-tidal partial pressure of carbon dioxide and arterial blood gas and pH were measured. ResultsButorphanol reduced MACISO in a dosage-dependent manner, by 23 ± 8%, 37 ± 12% and 68 ± 10% (mean ± standard deviation) in treatments LD, MD and HD, respectively. The main cardiopulmonary effect observed was a decrease in pulse rate, significant in treatment HD compared with control. Conclusions and clinical relevanceButorphanol caused a dosage-dependent MACISO reduction in cats. IV infusion of butorphanol may be of interest for partial IV anesthesia in cats.

Effects of dopamine, norepinephrine or phenylephrine on the prevention of hypotension in isoflurane-anesthetized cats administered vatinoxan or vatinoxan and dexmedetomidine

ObjectiveTo determine the dose of phenylephrine, norepinephrine and dopamine necessary to maintain mean arterial pressure (MAP) within 70–80 mmHg during administration of isoflurane, isoflurane and vatinoxan and isoflurane, vatinoxan and dexmedetomidine at three plasma concentrations. Study designRandomized crossover experimental study. AnimalsA group of five adult healthy neutered male cats. MethodsInstrumentation occurred during anesthesia with isoflurane in oxygen. Isoflurane end-tidal concentration was set to 1.25 × minimum alveolar concentration (MAC). Phenylephrine, norepinephrine or dopamine was administered to maintain MAP 70–80 mmHg. A target-controlled infusion system was used to administer vatinoxan at a target plasma concentration of 1 μg mL–1 and three dexmedetomidine concentrations (5, 10 and 20 ng mL–1). Isoflurane concentration was altered to maintain an equivalent 1.25 MAC. Heart rate, arterial blood pressure, central venous pressure, pulmonary artery pressure, pulmonary artery occlusion pressure, body temperature, arterial and mixed venous blood gas, cardiac output and drug concentrations were measured at baseline (isoflurane alone), during vatinoxan administration, and during administration of vatinoxan and dexmedetomidine at the three target concentrations. ResultsMAP < 70 mmHg was observed with vatinoxan alone and in the dopamine treatment with dexmedetomidine concentrations ≤ 10 ng mL–1. Norepinephrine and phenylephrine maintained MAP 70–80 mmHg during vatinoxan and dexmedetomidine ≤ 10 ng mL–1. As the target dexmedetomidine concentration increased, the dose of norepinephrine and phenylephrine needed to maintain MAP 70–80 mmHg decreased; no treatment was necessary to maintain MAP > 70 mmHg at the 20 ng mL–1 target dexmedetomidine concentration in most cats. Conclusions and clinical relevanceNorepinephrine and phenylephrine, but not dopamine, are effective to prevent hypotension in isoflurane-anesthetized cats administered dexmedetomidine and vatinoxan.

PSV-B-19 Dietary choline supplementation increases transmethylation through the one-carbon cycle in overweight cats

Abstract The objective of this study was to determine the dose-response relationship between dietary choline intake and one-carbon cycle activity in overweight cats at maintenance energy requirements. This study was approved by the University of Guelph Animal Care Committee (AUP#4118). Overweight (body condition score:≥6/9) adult male neutered cats (n = 14) received each of five choline chloride doses individually for three weeks in a 5x5 latin square design. Doses were based on body weight (BW) and the daily recommended allowance (RA) for choline for adult cats (63 mg/kg BW0.67). Doses were: 2xRA (126 mg/kg BW0.67), 4xRA (252 mg/kg BW0.67), 6xRA (378 mg/kg BW0.67), 8xRA (504 mg/kg BW0.67), and control (no additional choline). Choline was administered onto the commercial extruded cat food (3620 mg choline/kg diet), given once a day at maintenance energy requirements (130 kcal/kg BW0.4). Fasted serum samples were analyzed for metabolomics through quantitative nuclear magnetic resonance (NMR) spectroscopy and direct infusion mass spectrometry (DI-MS) at the end of each period. Data was analyzed using proc GLIMMIX in SAS, with group and period as the random effects, and dose as the fixed effect. Statistical significance was considered at P &amp;lt; 0.05. Tukey’s post-hoc test was performed to assess multiple comparisons. Choline at 6x and 8x RA appears to increase transmethylation through the one-carbon cycle, as suggested by increased serum betaine, dimethylglycine (DMG) and methionine (P &amp;lt; 0.05). Carnitine, methylated by s-adenosylmethionine (SAM), increased (P &amp;lt; 0.05). Serine and threonine, precursors for the biosynthesis of homocysteine, appear to have been spared (P &amp;lt; 0.05). Supplemental dietary choline (6x and 8xRA) may be beneficial for overweight cats, as it may increase activity of the one-carbon cycle and methyl status; which are necessary for hepatic function. To better understand the impact of choline on methylation reactions, the quantification of specific proteins, gene expression and/or conversion rates is required.

Pharmacokinetics of butorphanol in male neutered cats anesthetized with isoflurane.

This study characterized the pharmacokinetics of butorphanol in cats anesthetized with isoflurane. Six young healthy male neutered cats were used. Cats were anesthetized with isoflurane in oxygen. Catheters were placed in a jugular vein for blood sampling and in a medial saphenous vein for butorphanol and lactated Ringer's solution administration. Butorphanol tartrate (1 mg/kg over 5 min) was administered intravenously. Blood samples were collected prior to butorphanol administration and at various times up to 365 min following administration. Plasma butorphanol concentration was measured using liquid chromatography/tandem mass spectrometry. Compartment models were fitted to the time‐concentration data using nonlinear mixed effect modeling. A three‐compartment model best fitted the data. Typical value (% interindividual variability) for the three volumes of distribution, the metabolic clearance, and the two distribution clearances were 230 (72), 1095 (not estimated), and 2596 (not estimated) ml/kg, and 18.4 (72), 169.6 (52), and 55.0 (43), respectively. Pharmacokinetic simulation suggested that a loading dose (µg/kg) calculated as 0.287 × target plasma concentration in ng/ml (CT) followed by intravenous infusions (µg/kg/min) of 0.098 × CT for 20 min, 0.049 × CT for 40 min, and 0.022 × CT thereafter would rapidly achieve and maintain CT ± 10% for up to 6.5 h.