Research on Companion Animal Nutrition

Plant extracts, such as olive extract (OE), have been used in human and pet foods for their biological benefits; however, no available data have demonstrated OE’s effect on palatability in dogs. The current study aimed to evaluate acceptance of dry and canned dog foods with differing inclusions of OE as a flavor component. Flavor compounds in OE were analyzed by gas chromatography–mass spectrometry and high-pressure liquid chromatography, detecting 137 volatile compounds, including acetic acid and hydroxytyrosol. Dog kibbles were coated with liquid commercial palatants containing OE that resulted in application rates of 0 (control), 120, 200, and 500 ppm of OE in the diets. OE was also added at 0 (control), 120, 200, and 500 ppm into a wet food formulation with a commercial palatant before retort processing. Two separate panels of adult beagles were used for monadic testing to determine acceptance rates for kibble (5/treatment; 20 total) and canned foods (4/treatment; 16 total) in a 4 × 4 Latin square design. None of the tested inclusions impacted food acceptance in this preliminary study (p > 0.05). As a flavor ingredient, OE can be added into dry or wet dog food up to 500 ppm without deterring effects on palatability. Full article

Olive extract (OE) has been used in human foods for its nutraceutical effects, making it a product of interest for pet food. However, OE’s effect on palatability has not been examined. The study objective was to evaluate the palatability of dry cat foods with OE applied at differing inclusions within liquid or dry palatants. Twenty-seven volatile compounds were identified by gas chromatography–mass spectrometry for a potentially earthy or fruit-like flavor profile. Liquid palatants were formulated to supply 0 (control), 15, 30, 50, 75, and 150 ppm OE, and dry palatants were formulated to provide 0, 100, 200, 400, and 600 ppm OE when coated onto kibble. Palatability was evaluated using two-day, two-bowl testing of OE-containing versus control rations in adult cats (n = 20) with two-tailed t-tests to determine if OE affected intake ratio (IR). The observed IR of rations with OE were 0.45 to 0.56. The only preference was the 200 ppm treatment (IR = 0.56; p = 0.01) while the other OE rations were not different from the control (p ≥ 0.05). These findings indicate that palatant formulations can supply kibble diets with up to 150 ppm OE for liquid and 600 ppm for dry applications without negatively impacting cat food palatability. Full article

Tailoring diet to support a healthy gut microbiome is key for animal well-being. The gut metabolome, including all small molecules in the gut, is central to diet–microbiome–health interactions. While comprehension of the gut metabolome in companion animal nutrition is emerging, a substantial number of studies have been undertaken to elucidate the metabolomic shifts and identify specific marker metabolites influenced by diverse dietary interventions. By employing various metabolomic approaches, researchers have extensively documented the effects of different diet types, nutrient compositions, and dietary supplements on the gut metabolome in dogs and cats. Despite these advancements, there remains several notable limitations, including a lack of integrated microbiome analysis, incomplete understanding of specific marker metabolites, and an over-reliance on extrapolating findings from human studies. Therefore, this review aims to summarize the current understanding of the canine and feline gut metabolome, while exploring future possibilities and challenges for the field. Full article

Objectives: Sodium butyrate (SB) is a typical postbiotic known to positively affect economic animals in recent years, but research on SB in pet cats is scarce. Consequently, this study sought to explore the influence of SB on anti-inflammatory and antioxidant capacity, immune function, and gut microbiota of adult cats through the assessment of biochemical parameters and comprehensive integrative omics analysis. Methods: A total of 30 adult cats were divided into three groups: a basal diet (NC), basal diet with 0.05% SB (SB5), and basal diet with 0.1% SB (SB10). The experiment lasted for 6 weeks. Results: The results indicated that the fecal level of calprotectin was lower in the SB10 group than in the SB5 and NC groups. The SB10 group reduced the serum levels of TNF-α, IL-1β and DAO compared with the NC group (p < 0.05). In addition, the SB10 diet increased the GSH-Px level and decreased MDA content compared with the NC diet (p < 0.05). Transcriptomic analysis showed that the gene expression of VCAM1 exhibited a notable decrease in the SB10 group compared to the NC group (p < 0.05). The analysis of gut microbiota revealed that the richness of gut microbiota was higher in the SB10 than in the NC group (p < 0.05), and the abundance of Lachnospiraceae, Lachnoclostridium, Blautia, and Roseburia was greater in the SB10 than in the NC group (p < 0.05). Conclusions: Dietary SB could enhance the antioxidant and anti-inflammatory capacity, improve immune function, and positively regulate the gut microbiota composition in adult cats. Full article

Melatonin (MLT), produced by the pineal gland and other tissues, is known for its anti-inflammatory effects, particularly in regulating inflammatory markers and cytokines in intestinal cells. Our study aimed to investigate how MLT influences the expression of inflammatory genes through histone modification in canine ileum epithelial cells (cIECs). In our experiment, cIECs were cultured and divided into a control group (CON) and an MLT-treatment group. MLT did not significantly affect cell growth or death in cIECs compared to the CON. However, MLT treatment led to an upregulation of CD40, ZAP70, and IL7R and a downregulation of LCK, RPL37, TNFRSF13B, CD4, CD40LG, BLNK, and CIITA at the mRNA expression level. Moreover, MLT significantly altered the NF-kappa B signaling pathway by upregulating genes, such as CD40, ZAP70, TICAM1, VCAMI, GADD45B, IRAK1, TRADD, RELA, RIPK1, and RELB, and downregulating PRKCB, LY96, CD40LG, ILIB, BLNK, and TNFRSF11A. Using ChIP-qPCR, we discovered that MLT treatment enhanced histone acetylation marks H3K9ac, H3K18ac, H3K27ac, and methylation marks H3K4me1 and H3K4me3 at the ZAP70 and CD40 gene loci (p < 0.05). Additionally, the enrichment of RNA polymerase II and phosphorylated Ser5 pol-II at these loci was increased in MLT-treated cells (p < 0.05), indicating heightened transcriptional activity. In conclusion, our findings suggest that MLT mitigates inflammation in cIECs by modulating the transcription of ZAP70 and CD40 through histone modifications, offering potential therapeutic insights for inflammatory bowel diseases. Full article

Feeding raw meat to cats and dogs has become a common practice in Western countries. Many pet owners cite their pets’ wild carnivore ancestry and believe raw meat diets are healthier, citing higher nutritional value, a lack of processing, low-carbohydrate content, and/or the presence of whole ingredients. However, due to the risks associated with raw meat-based diets (e.g., microbial contamination, nutritional imbalances) and growing concerns about food sustainability, most nutritional specialists and public health stakeholders question the practice of feeding raw meat. In this context, the vast majority of owners’ claims regarding the beneficial health effects of raw meat diets lack scientific substantiation, while professional advice primarily focuses on risks, often overlooking potential positive health effects. To better understand the effects of raw meat diets on the health of cats and dogs, this review summarises the latest scientific evidence and discusses both the potential health benefits and the risks associated with these diets. Full article

This study aimed to investigate the effects of dietary supplementation with methylsulfonylmethane (MSM) and myo-inositol (MI) on hair quality, fecal microbiota, and metabolome in poodles. Thirty-two adult poodles categorized based on initial body weight and sex were randomly assigned to four groups. These groups (designated the CON, MSM, MI, and MSM + MI groups) received a basal diet, the same diet supplemented with 0.2% MSM + 0% MI, the same diet supplemented with 0% MSM + 0.2% MI, or the same diet supplemented with 0.2% MSM + 0.2% MI, respectively. The study lasted for 65 days. During the entire study period, body weight, average daily weight gain, feed intake, energy intake, and fecal output were normal in all the animals and did not differ significantly among the treatment groups. Hair scale thickness was lower in the MI and MSM + MI groups than in the CON group on Day 65 (p < 0.05). An amino acid analysis of the hair revealed higher sulfur content in the MI and MSM + MI groups on Day 65 than on Day 0 (p < 0.05). Moreover, the poodles in the MSM, MI, and MSM + MI groups presented significantly lower levels of Proteobacteria_unclassified and Candidatus Phytoplasma than did those in the CON group. The relative abundance of Gammaproteobacteria_unclassified was greater in the MSM and MI groups than in the CON group (p < 0.05). The MSM group presented a greater abundance of Glucerabacter than the CON group (p < 0.05). Compared with those in the CON and MSM + MI groups, the abundances of Paramuribaculum and Hafnia in the MSM group were greater (p < 0.05). The abundances of Enterobacter and Kineothrix were greater (p < 0.05) in the MI group than in the CON and MSM + MI groups. The poodles in the MI group presented significantly greater abundances of Bacteroidales_unclassified, Halanaerobium, Mycobacterium, and Erysipelotrichaceae_unclassified than did poodles in the CON, MSM, and MSM + MI groups. Fecal metabolomics analysis revealed that MSM, MI, and MSM + MI treatment markedly affected carbohydrate metabolism. MSM + MI treatment also influenced lipid metabolism. These findings suggest that dietary supplementation with MSM and MI can improve the hair quality of poodles. Full article

Frozen meat is an important source of protein in pet food, and has attracted much attention in recent years. In this study, we compared the effect of meat meal (MM), frozen meat (FM), and hydrolyzed frozen meat (HFM) as ingredients in extruded pet food on its palatability and apparent digestibility, as well as its effects on the immune response, fecal microbiota, and metabolome of British shorthair cats. A total of 24 British shorthair cats were allocated to the MM, FM, and HFM groups according to body weight and gender. The palatability test lasted 4 days and the feeding test lasted 45 days. The results showed that the FM and HFM diets had better palatability than the MM diet (p < 0.05) and significantly improved dry matter and crude protein digestibility (p < 0.05). The serum IL-10 level was significantly higher in the HFM group compared to the MM and FM groups (p < 0.05). The serum IgM levels were also found to be significantly higher in the FM group compared to the MM and HFM groups (p < 0.05). The blood urea nitrogen/creatinine ratio was significantly lower in the HFM and FM groups than in the MM group (p < 0.05). Cats fed HFM had a higher abundance of fecal Actinobacteria and Bifidobacterium and a lower content of Bacteroidota (p < 0.05). Furthermore, serum metabolomics analysis revealed that the tryptophan (Trp) metabolism and bile acid metabolism were affected by HFM. Overall, FM and HFM were better for the cat’s health than meat meal, but they also have some potential risks. Full article

Aminoaciduric canine hypoaminoacidemic hepatopathy syndrome (ACHES) is a rare syndrome affecting dogs. Nutritional management is a pillar of optimal treatment. Currently, there are no specific published data to inform dietary nutrient composition selections for treating affected dogs. Thus, our goal was to establish nutrient targets for the dietary management of ACHES by comparing nutrient profiles of commercial and home-cooked diets fed to dogs after diagnosis and determine if different nutrient inclusions were associated with survival. This retrospective cohort study evaluated nutrient profiles of commercial diets (n = 10) and home-cooked diets (n = 8) fed to dogs with ACHES. Associations between dietary nutrient inclusions and survival duration were determined using Cox proportional hazard analysis. Home-cooked diets were significantly (p < 0.001) higher in dietary protein and several amino acids than commercial diets. Risks of death were significantly (p < 0.05) lower with increasing dietary protein (hazard ratio 0.92 [CI 0.82–1.0]) and sodium (hazard ratio 0.02 [CI < 0.01–0.38]) and higher for dietary fat (hazard ratios 1.15 [CI 1.02–1.37]). An increased risk of death with increasing dietary calcium did not achieve significance (p = 0.067, hazard ratio 9.92 [CI 1.02–201.0]). These results were used to recommend target dietary nutrient ranges, in g/1000 kcal, of 90–130 for protein, 20–40 for fat, 0.7–1.8 for sodium, and 1.0–2.8 for calcium for dietary ACHES management. Full article

Plant extracts, derived from various natural sources, encompass primary and secondary metabolites, which include plant polysaccharides, polyphenols, alkaloids, flavonoids, glycosides, terpenes, and volatile oils. These compounds exhibit a range of biological activities such as antioxidant, anti-inflammatory, and antimicrobial functions. Currently, polyphenols and other bioactive compounds are being incorporated into the diets of farm animals, fish, and pets to promote health benefits. Despite this, the application and potential of plant extracts in canine and feline nutrition have not been comprehensively explored. Many aspects of the mechanisms underlying the action of these plant metabolites remain to be analyzed and elucidated. Furthermore, leveraging natural plant extracts for the treatment of clinical conditions in dogs and cats is a crucial component of clinical nutrition. Consequently, this review aims to highlight the impact of plant extracts on overall health, gastrointestinal health, immune health, cardiovascular health, redox balance, and pathology in dogs and cats. Full article

Trace minerals are essential for biological processes, including enzyme function, immune response, and hormone synthesis. The study assessed the effects of different dietary trace minerals on the gut health, microbiota composition, and immune function of cats. Eighteen adult British Shorthair cats were divided into three groups receiving inorganic trace minerals (ITM), a 50/50 mix of inorganic and organic trace minerals (ITM + OTM), or organic trace minerals (OTM) for 28 days. The OTM showed enhanced immune capacities, reduced intestinal barrier function, and lower inflammation condition. The OTM altered gut microbiota diversity, with a lower Simpson index and higher Shannon index (p < 0.05). Specifically, the abundance of Bacteroidota, Lachnospiraceae, and Prevotella in the OTM group were higher than the ITM group (p < 0.05). Metabolomic analysis identified 504 differential metabolites between the OTM and ITM groups (p < 0.05, VIP-pred-OPLS-DA > 1), affecting pathways related to steroid hormone biosynthesis and glycerophospholipid metabolism (p < 0.05, VIP-pred-OPLS-DA > 2). Additionally, there was a significant correlation between intestinal microbiota and differential metabolites. To conclude, dietary OTM can modulate the gut metabolite and microbiota composition, enhance immune and intestinal barrier function, and mitigate inflammation in cats, highlighting the benefit of using OTM in feline diet to promote the intestinal and overall health. Full article

An estimated USD 5.59 billion is spent on dog treats annually; yet little is known about the purchasing decisions of dog owners. The study objective was to conduct consumer research on a novel treat in comparison to three commercially available products. Participants (n = 70) were recruited from a Texas university campus. Respondents were shown four different treat products individually, without packaging, and asked to rate attributes such as aroma and texture, recording choices via an electronic survey. Packaging of the treat products was then shown and respondents were asked to rate marketing attributes such as ingredients and packaging type. Treat attribute likeness scores differed across brands for aroma, texture, and overall appearance (p < 0.001), with the novel product having the lowest overall average score (p < 0.05). All treat attributes were correlated with owner-predicted dog likeness (p < 0.001). Package type and all marketing attributes differed between products; the novel product had the lowest likeness scores in both categories (p < 0.05). Overall packaging appearance was correlated with respondents’ willingness to pay for a product (p < 0.001). A general linear model predicted a dollar value increase of USD 1.31 for every one unit increase in overall appearance likeness score. Respondents were willing to pay the least for the novel product when compared to all other products. Purchase intent was different across brands and was lowest for the novel product (p < 0.001); purchase intent correlated with all marketing attributes but not brand (p < 0.001). Both treat characteristics and marketing attributes may affect consumer’s purchase intent while simultaneously influencing the price they are willing to pay. Novel products may be less preferred by consumers, especially if compared against established commercial products. Full article

With the rising popularity of pet cats as companion animals, the survival of newborn kittens is often threatened by factors such as inadequate nursing, maternal behavior and blood incompatibility. These challenges require the use of milk replacers for nurturing. To investigate the effects that feeding kittens with an experimental milk replacer (EMR) have on growth and development, intestinal microbiota, immune response and nutrient metabolism, 12 British shorthair kittens were randomly divided into two groups after nursing for the first week of life. Kittens were fed queen’s milk or EMR, whereby kittens fed queen’s milk served as the control (CON) group. The findings revealed that the CON group exhibited superoxide dismutase (SOD) activity and total antioxidant capacity (T-AOC) (p < 0.01) on day 7. However, the EMR group had better growth performance during the later stage of the experiment (p < 0.05); the immunocompetence and antioxidant capacity of the EMR group were not significantly different from those of the CON group in the middle and late stages of the experiment, and the mean values of all the indexes were slightly better than those of the control group. Sequencing of the 16S rRNA gene in microbiota demonstrated that EMR increased the colonization of bacterial genera, including Lachnospiraceae, Enterococcus, Rothia and Ligilactobacillus. Compared to the CON group, acetate acid (p < 0.05), propionate acid (p < 0.01) and total SCFAs (p < 0.01) in the EMR group were significantly increased. Moreover, the intake of the EMR resulted in the production of distinct metabolites implicated in the metabolism of lipids and amino acids, among other nutrients, thus invigorating the associated metabolic pathways. These results elucidate the impact of administering a milk replacer on gastrointestinal health and nutrient assimilation in kittens. The study provides insights into the use of milk powder alternatives and sets the stage for future research on the formulation and effectiveness of kitten milk replacers. Full article

Probiotics demonstrated effectiveness in modulating oral microbiota and improving oral health in humans and rodents. However, its effects and applications on the oral microbiota of cats remain underexplored. Twelve healthy cats were randomly assigned to a control group (CON) and a composite probiotic group (CPG) for a 42-day trial. The CPG diet included additional supplementation of Bifidobacterium animalis subsp. lactis HN019, Lactobacillus acidophilus NCFM, and Lactobacillus casei LC-11, each at approximately 1 × 10¹⁰ CFU/kg. On days 0 and 42, microbial samples were collected from the gingiva, tooth surfaces, and tongue of all cats for 16S rRNA gene sequencing. Bacteroidetes, Firmicutes, and Proteobacteria were the dominant phyla across all oral sites. The CPG treatment enriched seven genera, such as Moraxella, Actinomyces, and Frederiksenia in the gingiva. Meanwhile, Bergeyella and Streptococcus were enriched on the tooth surfaces, while Bergeyella, Flavobacterium, and Luteimonas were enriched on the tongue. Furthermore, the composite probiotic effectively suppressed eight genera, such as Bacteroides, Desulfovibrio, and Filifactor in the gingiva of CPG cats, as well as Helcococcus, Lentimicrobium, and Campylobacter on tooth surfaces, and Porphyromonas, Treponema, and Fusibacter on the tongue. These findings suggest that the composite probiotic used in this study modulates the feline oral microbiota by supporting beneficial or commensal bacteria and inhibiting oral pathogens, demonstrating potential to improve oral health in cats. Full article

Companion animals such as dogs and cats play a crucial role in modern families. Their overall health is significantly influenced by their gut health, with many health disorders arising from disturbances in the gut microbiome. Our review highlights the ability of probiotics and nutraceuticals to modify the gut microbiota and enhance gastrointestinal health in canine and feline species. We investigated the effects of probiotics and natural antioxidant molecules on digestion, immunological response, and barrier integrity in gastrointestinal health studies concerning dogs and cats. The analysis indicated that probiotics influence gut microbiota composition in a positive manner, enhance digestion, augment the immune response, and help to maintain barrier integrity. Additionally, natural products with antioxidant molecules showed the potential to improve gut health and protect pets from various illnesses. We concluded by advocating the need for more studies in this direction to fully understand their effects and optimize their use in veterinary medicine. Full article

The booming aquaculture industry has created a strong demand for fishmeal and increased environmental pressures. Spirulina, as a potential alternative to fishmeal, has been shown to have growth-promoting and animal health-enhancing properties. In this study, 600 large spiny loaches, divided into five experimental groups, F0, F1, F2, F3, and F4, were reared for 10 weeks using Spirulina platensis powder (SPP) as a substitute for 0%, 5%, 10%, 15%, and 20% of fishmeal, respectively. The results of intestinal physiological indexes showed that superoxide dismutase was lower than F0 in all treatment groups, and the activity of F3 was significantly lower than F0 (p < 0.05). The activity of malondialdehyde was significantly higher than that of F0 in all groups except F3 (p < 0.05). The addition of SPP also led to a decrease in the activity of acid phosphatase in the intestine, which was significantly lower in all treatment groups compared to the F0 group (p < 0.05). The results of serum physiology showed that the activity of superoxide dismutase in serum gradually increased with the increase in the percentage of SPP addition, and the F3 group produced a significant difference from the F0 group (p < 0.05). The transcriptomics results showed that DEGs in the low percentage substitution group (<15%) were mostly enriched in metabolism-related pathways, such as bile secretion; DEGs in the high percentage substitution group (>15%) were mostly enriched in inflammation-related pathways, such as complement p and coagulation cascades. Metabolomics confirmed that nicotinate and nicotinamide metabolism and glycerophospholipid metabolism were the two pathways that were significantly enriched in the treatment groups of fishmeal replacement by SPP. The present study demonstrated that a low percentage (<15%) of fishmeal replacement by SPP in feed mobilized MA digestive metabolism, whereas a high percentage (>15%) of replacement induced intestinal stress. Considering the health and farm efficiency aspects, the proportion of SPP in feed formulation for MA should be less than 15%. Full article

The intestinal microbiome changes with age, influencing the host’s health and immune status. Saccharomyces cerevisiae (S. cerevisiae) positively affects intestinal function in humans and animals, but its effects on gut health and the microbiota profile in aged dogs have not been thoroughly investigated. Twenty aged Labrador Retrievers were divided into two groups: a control group (CON) and a S. cerevisiae group (SC). The experiment lasted for 42 days, with assessments of their intestinal barrier function, inflammatory factors, antioxidant markers, and fecal microbiome composition. The results showed that dietary S. cerevisiae reduced the levels of TNF-α, IL-6, and IL-1β in the serum (p < 0.05). In the SC group, plasma superoxide dismutase and glutathione peroxidase activities increased, while the level of malondialdehyde significantly decreased (p < 0.05). Additionally, dietary S. cerevisiae lowered the serum zonulin and lipopolysaccharide (LPS) levels (p < 0.05) and inhibited fecal ammonia production (p < 0.05). Furthermore, the microbiota profile showed that dietary S. cerevisiae decreased the abundance of Firmicutes but increased the Chao index, the abundance of Bacteroidetes, and the proportion of Bacteroidetes to Firmicutes (p < 0.05). To conclude, dietary S. cerevisiae can regulate the gut’s microbial structure and gut health, which may contribute to the overall health of companion animals as they age. Full article

This study evaluated the nutrition composition, the nutrient digestibility, and the energy value of six protein ingredients used in pet food by the difference method in six beagles within a 7 × 6 incomplete Latin square design. The results showed that the apparent total tract digestibility of gross energy (GE) and organic matter (OM) in beagles fed the fish meal (FM) and corn gluten meal (CGM) diets was higher than for those fed the meat and bone meal (MBM), soybean meal (SBM), mealworm meal (MM), and yeast extract (YE) diets (p < 0.05). The digestible energy (DE), metabolizable energy (ME), and net energy (NE) of the MM diet were greater than the other diets, and MBM was the lowest (p < 0.05). The ME of protein ingredients was positively correlated with organic matter and negatively correlated with the ash content. The NE of protein ingredients was positively correlated with the crude protein content and negatively correlated with the ash content. The study resulted in predictive energy equations for protein ingredients that were more accurate than the NRC’s predictive equation of ME when the ash content of the ingredient was more than 30% DM. In conclusion, the nutrient digestibility and energy value of corn gluten meal were similar to those of fish meal and those of soybean meal were similar to yeast extract. All predictive energy equations for six protein feedstuffs had slight differences with measured energy values. Full article