The Fecal Microbiota in the Domestic Cat (Felis catus) Is Influenced by Interactions Between Age and Diet; A Five Year Longitudinal Study.

In humans, aging is associated with changes in the gastrointestinal microbiota; these changes may contribute to the age-related increase in incidence of many chronic diseases, including Type 2 diabetes. The life expectancies of cats are increasing, and they are also exhibiting the same types of diseases. While there are some studies investigating the impacts of diets on gastrointestinal microbiota in young cats, the impacts of aging in older cats has not been explored. We followed a cohort of related kittens, maintained on two commercial diets (kibbled and canned) from weaning (8 weeks) to 5 years of age (260 weeks). We hypothesized that the long-term feeding of specific diet formats would (a) lead to microbial composition changes due to aging, (b) impact body composition, and (c) affect insulin sensitivity in the aging cat. We observed that both diet and age affected fecal microbial composition, and while age correlated with changes in body composition, diet had no effect on body composition. Similarly insulin sensitivity was not affected by age nor diet. 16S rRNA sequencing found unclassified Peptostreptococcaceae were prominent across all ages averaging 21.3% of gene sequence reads and were higher in cats fed canned diets (average of 25.7% of gene sequence reads, vs. 17.0% for kibble-fed cats). Age-related effects on body composition and insulin sensitivity may become apparent as the cats grow older; this study will continue to assess these parameters.

Effect of age, sex and body weight on the serum concentrations of cobalamin and folate in cats consuming a consistent diet.

Objectives Multiple feline diseases involving the gastrointestinal tract, pancreas, liver and biliary tract are known to cause abnormal serum cobalamin and folate concentrations. Measuring the serum concentration of these vitamins can therefore be a helpful diagnostic tool. However, factors other than disease, in particular age, have also been suggested to have an effect on the serum concentration of cobalamin and folate. In previous studies, the dietary intake was not standardised, or even known, despite diet being the prinicpal source of both vitamins. Therefore, we evaluated the effect of age, sex and body weight on the serum concentration of folate and cobalamin in cats fed the same diet. Methods The serum cobalamin and folate concentrations were measured in 65 apparently healthy cats in a nutrition colony that had been fed an identical diet. A linear model was used to test the relationship between the serum concentration of cobalamin and folate with the variables age, sex and body weight. Results There was a large variation in the serum concentration of both folate and cobalamin, despite identical intake. Serum cobalamin was inversely associated with age ( P = 0.002), and males had higher concentrations than females ( P = 0.039). Serum folate was positively associated with age ( P = 0.01). Conclusions and relevance Independent of diet, serum cobalamin concentration decreases with age. Changes in gastrointestinal function, microflora or metabolism may be responsible. Older cats may be more susceptible to cobalamin deficiency secondary to inappetence or gastrointestinal disease.

Key bacterial families (Clostridiaceae, Erysipelotrichaceae and Bacteroidaceae) are related to the digestion of protein and energy in dogs.

BACKGROUND: Much of the recent research in companion animal nutrition has focussed on understanding the role of diet on faecal microbiota composition. To date, diet-induced changes in faecal microbiota observed in humans and rodents have been extrapolated to pets in spite of their very different dietary and metabolic requirements. This lack of direct evidence means that the mechanisms by which microbiota influences health in dogs are poorly understood. We hypothesised that changes in faecal microbiota correlate with physiological parameters including apparent macronutrient digestibility. METHODS: Fifteen adult dogs were assigned to two diet groups, exclusively fed either a premium kibbled diet (kibble; K; n = 8) or a raw red meat diet (meat; M; n = 7) for nine weeks. Apparent digestibility of macronutrients (protein, fat, gross energy and dry matter), faecal weight, faecal health scores, faecal VFA concentrations and faecal microbial composition were determined. Datasets were integrated using mixOmics in R. RESULTS: Faecal weight and VFA levels were lower and the apparent digestibility of protein and energy were higher in dogs on the meat diet. Diet significantly affected 27 microbial families and 53 genera in the faeces. In particular, the abundances of Bacteriodes, Prevotella, Peptostreptococcus and Faecalibacterium were lower in dogs fed the meat diet, whereas Fusobacterium, Lactobacillus and Clostridium were all more abundant. DISCUSSION: Our results show clear associations of specific microbial taxa with diet composition. For example, Clostridiaceae, Erysipelotrichaceae and Bacteroidaceae were highly correlated to parameters such as protein and fat digestibility in the dog. By understanding the relationship between faecal microbiota and physiological parameters we will gain better insights into the effects of diet on the nutrition of our pets.

Investigation of cell-free DNA in canine plasma and its relation to disease.

BACKGROUND: DNA is released from dying cells during apoptosis and necrosis. This cell-free DNA (cfDNA) diffuses into the plasma where it can be measured. In humans, an increase in cfDNA correlates with disease severity and prognosis. OBJECTIVE: It was hypothesized that when DNA in canine plasma was measured by emission fluorometry without prior DNA extraction, the concentration of cfDNA would increase with disease severity. ANIMALS: The diseased population consisted of 97 client-owned dogs. The clinically normal population consisted of nine client-owned dogs presenting for 'wellness screens', and 15 colony-owned Harrier Hounds. METHODS: Plasma cfDNA was measured by fluorometry without prior DNA extraction. The effects of ex vivo storage conditions were evaluated in plasma from two clinically normal dogs. In all other dogs, plasma was separated within two hours of collection. The association between the cfDNA concentration in hospitalized dogs and a variety of clinical, clinicopathological and outcome variables was tested. RESULTS: The concentration of cfDNA was reliably measured when plasma was separated within two hours of blood collection. The diseased dogs had significantly higher cfDNA than clinically normal dogs (P < 0.001), and the more severe the disease, the higher the cfDNA when severity was categorized according to the American Society of Anesthesiologists (ASA) status (P < 0.001). Dogs that did not survive to discharge had significantly higher cfDNA concentrations than survivors (P = 0.02). Conclusions/Clinical Importance: The concentration of cfDNA in the plasma of diseased dogs is associated with disease severity and prognosis. Measurement of canine cfDNA could be a useful non-specific disease indicator and prognostic tool.

Design and evaluation of a novel chitosan-based system for colon-specific drug delivery.

Tritrichomonas foetus is a flagellated protozoan parasite that colonizes the feline colon causing colitis and chronic foul smelling diarrhoea. Despite the efficacy of Ronidazole in the treatment of T. foetus, Ronidazole has been reported to cause neurotoxicity in some cats due to rapid absorption in the small intestine. A novel amphoteric derivative of chitosan was synthesised and characterized. A combination of time, pH, and an enzyme controlled system was used in a study of a new compression coated tablet for delivery of Ronidazole to the colon. Axial, radial swelling and erosion of selected tablets were carried out in various media. The effect of weight ratio, enzyme and pH on in vitro drug release profile was investigated. The results show that less than 2% of the drug was released in the physiological environment of the stomach and small intestine.

Energy requirements of adult dogs: a meta-analysis.

A meta-analysis was conducted to determine the maintenance energy requirements of adult dogs. Suitable publications were first identified, and then used to generate relationships amongst energy requirements, husbandry, activity level, methodology, sex, neuter status, dog size, and age in healthy adult dogs. Allometric equations for maintenance energy requirements were determined using log-log linear regression. So that the resulting equations could readily be compared with equations reported by the National Research Council, maintenance energy requirements in the current study were determined in kcal/kg(0.75) body weight (BW). Ultimately, the data of 70 treatment groups from 29 publications were used, and mean (± standard deviation) maintenance energy requirements were 142.8±55.3 kcal·kgBW(-0.75)·day(-1). The corresponding allometric equation was 81.5 kcal·kgBW(-0.9)·day(-1) (adjusted R2 = 0.64; 70 treatment groups). Type of husbandry had a significant effect on maintenance energy requirements (P<0.001): requirements were greatest in racing dogs, followed by working dogs and hunting dogs, whilst the energy requirements of pet dogs and kennel dogs were least. Maintenance energy requirements were less in neutered compared with sexually intact dogs (P<0.001), but there was no effect of sex. Further, reported activity level tended to effect the maintenance energy requirement of the dog (P = 0.09). This review suggests that estimating maintenance energy requirements based on BW alone may not be accurate, but that predictions that factor in husbandry, neuter status and, possibly, activity level might be superior. Additionally, more information on the nutrient requirements of older dogs, and those at the extremes of body size (i.e. giant and toy breeds) is needed.

Effects of physiologic concentrations of l-lysine on in vitro replication of feline herpesvirus 1.

OBJECTIVE: To evaluate the effects of various concentrations of l-lysine on in vitro replication of feline herpesvirus 1 (FHV-1). SAMPLE: Cultures of Crandell-Rees feline kidney (CRFK) cells. PROCEDURES: CRFK cells were inoculated with FHV-1 and maintained in media with 20 combinations of l-arginine and l-lysine concentrations. Changes in cell viability were monitored by continuous measurement of electrical impedance of cultured cells and by observation of viral cytopathic effects. Viral load was determined by use of quantitative PCR assay in supernatants obtained from infected cultures at specified time points. RESULTS: Increases in l-lysine concentration had no effect on the kinetics of cell death in FHV-1-infected cultures. There was also no significant effect (r(2) < 0.1) on viral DNA load for l-arginine concentrations ≥ 12 µg/mL There was a significant effect of increases in l-lysine concentration on viral DNA load in media supplemented with 6 µg of l-arginine/mL (mean ± SD slope, -4,641 ± 1,626 units; adjusted r(2) = 0.45). However, the difference between the lowest (1 × 10(6.28) copies/µL) and highest (1 × 10(6.86) copies/µL) FHV-1 DNA load in these media was < 1 logarithm. CONCLUSIONS AND CLINICAL RELEVANCE: The difference in FHV-1 DNA load was unlikely to be biologically important. Various l-lysine concentrations did not inhibit in vitro replication of FHV-1 at l-arginine concentrations sufficient to maintain cell growth. This conclusion was consistent with results of other studies in which investigators have not detected a consistently beneficial effect when l-lysine is administered to FHV-1-infected cats.

Dietary isoflavone absorption, excretion, and metabolism in captive cheetahs (Acinonyx jubatus).

Dietary isoflavones, capable of influencing reproductive parameters in domestic cats (Felis catus), have been detected in commercial diets fed to captive cheetahs (Acinonyx jubatus). However, the absorptive and metabolic capacity of cheetahs towards isoflavones has not yet been studied. Experiments were designed to describe the plasma concentration-time curve, metabolite profile, and urinary and fecal excretion of genistein and daidzein in cheetahs following consumption of isoflavones. Four adult cheetahs were administered a single oral bolus of genistein and daidzein, and five juvenile cheetahs consuming a milk replacer formula found to contain isoflavones were also included. Urine was collected from all animals, and blood and feces were also collected from adult cheetahs following isoflavone exposure. Samples were analyzed for isoflavone metabolite concentration by liquid chromatography-electrospray ionization-multiple reaction ion monitoring mass spectrometry and high-performance liquid chromatography. Sulfate conjugates were the primary metabolites detected of both genistein and daidzein (60-80% of total isoflavones present) in the plasma and urine of cheetahs. A smaller proportion of daidzein was detected as conjugates in the urine of juvenile cheetahs, compared to adult cheetahs. Other metabolites included unconjugated genistein and daidzein, O-desmethylangolensin, and dihydrodaidzein, but not equol. Only 33% of the ingested genistein dose, and 9% of daidzein, was detected in plasma from adult cheetahs. However, of the ingested dose, 67% of genistein and 45% of daidzein were detected in the feces of adults. This study revealed that cheetahs appear efficient in their conjugation of absorbed dietary isoflavones and only a small fraction of ingested dose is absorbed. However, the capacity of the cheetah to conjugate genistein and daidzein with sulfate moieties appears lower than reported in the domestic cat. This may confer greater opportunity for biologic activity of isoflavones in the cheetah than would be predicted from findings in the domestic cat. However, further investigation is required.

Modulation of innate and acquired immunity by an estrogenic dose of genistein in gonadectomized cats.

Dietary genistein has potential as a surrogate estrogen to restore normal control of food intake in cats following gonadectomy. However, since genistein affects immunological responses in other species it is important to determine if there is any immunological effect of genistein in cats, before long-term feeding of it could be considered. It was hypothesized that the minimum estrogenic dose of genistein (peak serum concentration 0.276+/-0.055 microg/mL) would be associated with altered innate and acquired immunity in cats. Cats (n=8 per group) were surgically neutered then treated daily with either 0.5 microg estradiol subcutaneously, 100mg/kg genistein orally, or vehicle only for 38 days. Circulating CD4+ and CD8+ T cells, and CD21+ B cells were quantified using flow cytometry. Concanavalin-A induced lymphocyte proliferation was assayed using incorporation of tritiated thymidine. Indirect ELISA was used to assay serum IgG in response to a commercial vaccine. Neutrophil respiratory burst in response to opsonized zymosan was evaluated using flow cytometric detection of oxidized dihydrorhodamine. Delayed-type hypersensitivity was evaluated with formalin-killed Yersinia pseudotuberculosis. Genistein treatment decreased circulating CD8+ cells (P=0.006), increased neutrophil respiratory burst (P=0.034), and increased wheal formation at 24h (P=0.038) but decreased wheal formation at 72 h (P=0.012) following intradermal challenge with killed Y. pseudotuberculosis. There were no significant differences between genistein treated cats and the other treatment groups in any other parameters. It is concluded that the minimum estrogenic dose of genistein alters selected leukocyte responses in cats. Unexpected effects of genistein suggest that extrapolation from one species to other species may not be appropriate in regards to the effects of genistein on immunity.

Hydrolyzed protein diets for dogs and cats.

The primary aim of a hydrolyzed protein diet is to disrupt the proteins within the diet sufficiently to remove existing allergens. Published assessment of hydrolyzed protein diets includes physiochemical and immunologic assays as well as nutritional and clinical feeding trials. Potential problems include poor palatability, hypoosmotic diarrhea, and a reduced nutritional value, although persistent allergenicity is the most significant. The primary indications for a hydrolyzed protein diet are use in elimination trials for the diagnosis of adverse food reactions, and the initial management of inflammatory bowel disease. Initial studies of hydrolyzed diet efficacy are encouraging. Consideration of the source ingredients should be given when using hydrolyzed protein diets in elimination feeding trials because antigenic sites may not be fully destroyed.

Evaluation of the immunogenicity of dietary proteins in cats and the influence of the canning process.

OBJECTIVE: To characterize the antigen-specific immune response to dietary proteins in cats and evaluate whether there was a qualitative or quantitative difference between the responses to dietary proteins when those proteins were fed unprocessed or as part of a canned diet. ANIMALS: 14 healthy domestic shorthair cats. PROCEDURE: Cats were fed 2 dietary proteins (soy and casein) either as unprocessed aqueous suspensions or as part of canned diets for 21 days. Serum IgG and IgA and salivary IgA were assayed by indirect ELISA, and antigen-specific proliferation of mesenteric lymph node-derived lymphocytes was determined. RESULTS: Robust serum IgG and IgA responses to dietary proteins were elicited, irrespective of the form in which they were fed. Salivary IgA responses to unprocessed proteins were not detected. However, a significant salivary IgA response to the protein isolated from the canned casein diet was observed in cats fed canned casein but not in those fed unprocessed casein. Lymphocyte proliferation to the antigens was slight, and there were no significant differences between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that cats develop robust serum IgG and IgA responses to dietary proteins when fed as either aqueous suspensions or as part of canned diets. For certain proteins, there may be an increase and a qualitative difference in the immunogenicity of canned diets, compared with unprocessed proteins. Canned diets may not be ideal for management of cats with enteritis.

Evaluation of a routine diagnostic fecal panel for dogs with diarrhea.

OBJECTIVES: To assess the diagnostic yield of a routine fecal panel and determine whether Clostridium perfringens or C difficile toxin production is associated with acute hemorrhagic diarrheal syndrome (AHDS) in dogs. DESIGN: Case-control study. ANIMALS: 260 dogs with diarrhea and 177 dogs with normal feces. PROCEDURE: Medical records were reviewed for results of culture for C difficile, Campylobacterspp, and Salmonella spp; C perfringens fecal enterotoxin (CPE) assay via ELISA or reverse passive latex agglutination (RPLA) assay; fecal endospore enumeration; C difficile toxin A assay; and parasite evaluation. RESULTS: Prevalence of CPE in dogs with diarrhea was 22/154 (14.3%) via ELISA and 47/104 (45.2%) via RPLA assay, versus 9/74 (12%) via ELISA and 26/103 (25%) via RPLA assay in control dogs. Prevalence of C difficile was 47/260 (18%) in dogs with diarrhea and 41/74 (55%) in control dogs. Prevalence of C difficile toxin A was 26/254 (10.2%) in dogs with diarrhea and 0/74 in control dogs. Diagnosis of AHDS was made in 27 dogs; 8 had positive results for CPE, 7 had positive results for toxin A, and 1 had positive results for both toxins. Campylobacter spp were isolated from 13 of 260 (5%) dogs with diarrhea and 21 of 74 (28.4%) control dogs. Salmonella spp were isolated from 3 (1.2%) dogs with diarrhea. CONCLUSIONS AND CLINICAL RELEVANCE: Diagnostic value of a fecal panel in dogs with diarrhea appears to be low.