Dry Dog Food Research Articles

Mycotoxins in commercial dry pet food in China

ABSTRACTThe aim of this study was to investigate the occurrence of the most common mycotoxins in commercial dry dog food using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Aflatoxin B1 (AFB1), aflatoxin G1 (AFG1), zearalenone (ZEN), deoxynivalenol (DON), T-2, beauvericin (BEA), citrinin (CIT), ochratoxin A (OTA), fumonisin B1 (FB1) were included in this study. The results showed that all these analytes could be found in the samples. Furthermore, only one sample was found free of mycotoxins contamination. All other samples (96.9%) were contaminated by at least three different types of mycotoxins. Among these mycotoxins, DON, ZEN, AFB1, FB1, CIT and BEA exhibited relatively high incidence, with occurrence rates of 78.1%, 62.5%, 87.5%, 93.8%, 68.8 and 96.9%, respectively. Furthermore, it is worth noting that AFB1 concentration in all AFB1 positive samples exceeded the maximum limits set by the European Union, with concentrations ranging from 30.3–242.7 µg/kg.

Pet and owner acceptance of dry dog foods manufactured with sorghum and sorghum fractions

Globally sorghum is an important cereal crop with limited use in the pet food industry. Pet food acceptance and palatability assessments relate to both pet owners as the product purchasers and the pets as the actual consumers. Pet foods containing sorghum or sorghum fractions have not been studied for both animal and pet owner acceptance. The objectives of this study were to 1) understand animal acceptance between sorghum dog food diets and compared to a control, 2) assess consumer acceptance of the dog food products. Thirty dogs of different size and breed were fed three dry dog food diets containing different sorghum fractions and one control diet containing wheat, rice, and maize using the one-bowl in home use test. Results indicated that no difference was observed among diets, and sorghum samples were accepted at the same level as the control diet during the test. A total of 105 pet owners evaluated the samples for appearance, color, aroma, and overall liking. The consumer panel found the whole sorghum and the control samples to be accepted at the same level. These results suggested that sorghum may be suitable for dry dog food formulations.

Evaluation of the iQ-Check®Salmonella II Assay in Select Foods: Collaborative Study, First Action 2017.06.

The iQ-Check Salmonella II Real-Time PCR test kit utilizes Salmonella-specific oligonucleotide probes and primers for the rapid and specific detection of Salmonella species in select food types. The alternative method was evaluated by using 375 g test portions in an unpaired study design for two matrices, milk chocolate and dry dog food. Each matrix was compared with the U.S. Food and Drug Administration Chapter 5 Salmonella reference method. Fourteen technicians from 12 laboratories, including academia and industry, located within the United States and Canada participated in the collaborative study. Three levels of contamination were evaluated for each matrix: an uninoculated control level (0 CFU/test portion), a low inoculum level (0.2-2 CFU/test portion), and a high inoculum level (2-5 CFU/test portion). The statistical analysis was conducted according to the Probability of Detection (POD) statistical model. The results obtained for the low inoculum level test portions produced a difference in the candidate presumptive and confirmatory results (dLPOD) value with a 95% confidence interval of -0.05, (-0.15, 0.06) for the milk chocolate and 0.10, (-0.01, 0.21) for the dry dog food. The dLPOD results indicate an equivalence between the candidate method and reference method for the matrices evaluated, and the method demonstrated acceptable interlaboratory reproducibility as determined in the collaborative evaluation. False positive and false negative rates were determined for each matrix and produce values of <2%. Based on the data generated, the method demonstrated acceptable interlaboratory reproducibility data and statistical analysis.

Mineral Composition of Dry Dog Foods: Impact on Nutrition and Potential Toxicity

Detailed mineral profile of a selection of commercially available complete dry dog foods was determined using ICP-MS (Se, Cu, Mn, Zn, and nonessential trace elements), flame photometry (Na and K) and atomic and molecular spectrophotometry (Ca, P, Mg, and Fe). The contribution of ingredients to the mineral composition was correlated to the food market segment. Results showed an oversupply of essential elements due to the energy density effect on feed intake. Additives contributed from 40.8 to 55.1% to the total trace elements contents. With the exception of Se, all trace elements were supplied above the nutritional requirements of adult dogs. Legal limits of Cu, Se, and Zn were surpassed. The content of nonessential trace elements included values in the range of nanograms to micrograms per kg, without surpassing safe upper limits. This work brings awareness to the need to find supplementation strategies that ensure nutritional adequacy and avoid waste.

Evaluation of selected ultra-trace minerals in commercially available dry dog foods.

PurposeTo evaluate the concentrations of chromium, nickel, molybdenum, silica, and aluminum in several commercially available dry dog foods and compare these with current World Health Organization’s (WHO) mean human daily dietary intake. Conversion of dietary intake per megacalorie (Mcal) for both dog foods and human average intake was performed based on the National Research Council recommendation of a 2,900 kcal diet for comparative purposes to average intake and potential toxic exposure.Materials and methodsForty-nine over-the-counter dry foods formulated for maintenance of healthy dogs yet listed as all life stage foods were analyzed. Concentrations of the ultra-trace minerals were measured via inductively coupled plasma atomic emission and represented per Mcal for comparative purposes as it relates to common intake in dogs in comparison with humans.ResultsChromium, molybdenum, and aluminum concentrations in all of the dog foods were at levels that would be considered above average human daily consumption on a caloric basis. Nickel and silica calculated intakes per Mcal were comparable with human intake patterns, while both trace minerals displayed outliers exceeding at least twofold of the upper range of human daily intake.ConclusionOverall, ultra-trace minerals found in dog foods were above the expected average daily intake for humans on a caloric basis. There was no evidence of potential chronic toxic exposure based on presumptive intake extrapolated from WHO published toxic intake concentrations for humans or domestic animals. The large range of silica intake from various foods (2.96–83.67 mg/1,000 kcal) may have health implications in dogs prone to silica urolithiasis. Further studies investigating the bioavailability of these ultra-trace minerals and establishing dietary ultra-trace mineral allowance would be ideal; however, based on these findings, consumption of these ultra-trace minerals in over-the-counter dry dog foods appears safe.

Acceptability of Dry Dog Food Visual Characteristics by Consumer Segments Based on Overall Liking: a Case Study in Poland.

Simple SummaryThe present work aimed to explore the response of dog owners to the appearance of pet foods. The objective of this study was to understand the impact of the visual characteristics of dry dog food on the human consumers’ acceptance and beliefs they associate with the products. The acceptability of the appearance of dry dog foods by consumers is influenced by the number of different kibbles present, color(s), shape(s), and size(s) in the product. The results indicated that dry dog food manufacturers should take special consideration with the appearance of the kibbles to enhance the acceptability of their products. These findings can help dry dog food manufacturers meet the consumers’ needs with increasing benefits to the pet food and commodity industries.Sensory analysis of pet foods has been emerging as an important field of study for the pet food industry over the last few decades. Few studies have been conducted on understanding the pet owners’ perception of pet foods. The objective of this study is to gain a deeper understanding on the perception of the visual characteristics of dry dog foods by dog owners in different consumer segments. A total of 120 consumers evaluated the appearance of 30 dry dog food samples with varying visual characteristics. The consumers rated the acceptance of the samples and associated each one with a list of positive and negative beliefs. Cluster Analysis, ANOVA and Correspondence Analysis were used to analyze the consumer responses. The acceptability of the appearance of dry dog foods was affected by the number of different kibbles present, color(s), shape(s), and size(s) of the kibbles in the product. Three consumer clusters were identified. Consumers rated highest single-kibble samples of medium sizes, traditional shapes, and brown colors. Participants disliked extra-small or extra-large kibble sizes, shapes with high-dimensional contrast, and kibbles of light brown color. These findings can help dry dog food manufacturers to meet consumers’ needs with increasing benefits to the pet food and commodity industries.

Qualitative and quantitative detection of chicken deoxyribonucleic acid (DNA) in dry dog foods.

Chicken is a common protein source in pet foods and is concurrently listed among food allergens. Commercial over-the-counter (OTC) diets with an alternative animal protein source are considered suitable for dietary elimination trials by pet owners. The potential presence of undeclared chicken-derived ingredients in these diets can compromise the outcome of the trial during the diagnosis of adverse food reactions. The aim of this study was to selectively verify the absence or presence of chicken DNA in 10 OTC dry canine foods, using qualitative and quantitative approaches. The method of identification of chicken-derived protein was elaborated with the polymerase chain reaction (PCR) technology, whereas quantitative real-time PCR was used for the quantitative assessment. In most of the analysed samples, the chicken DNA was detectable; however, the quantified amounts were predominantly low, although differences between batches were observed.

Toxicity assessment of mycotoxins extracted from contaminated commercial dog pelleted feed on canine blood mononuclear cells

Raw ingredients of pet food are often contaminated with mycotoxins. This is a serious health problem to pets and causes emotional and economical stress to the pet owners. The aim of this study was to determine the immunotoxicity of the most common mycotoxins (aflatoxin, fumonisin, ochratoxin A and zearalenone) by examining 20 samples of extruded dry dog food found on the South African market [10 samples from standard grocery store lines (SB), 10 from premium veterinarian lines (PB)]. Pelleted dog food was subjected to extraction protocols optimized for the above mentioned mycotoxins. Dog lymphocytes were treated with the extracts (24 h incubation and final concentration 40 μg/ml) to determine cell viability, mitochondrial function, oxidative stress, and markers of cell death using spectrophotometry, luminometry and flow cytometry. Malondialdehyde, a marker of oxidative stress showed no significant difference between SB and PB, however, GSH was significantly depleted in SB extract treatments. Markers of apoptosis (phosphatidylserine externalization) and necrosis (propidium iodide incorporation) were elevated in both food lines when compared to untreated control cells, interestingly SB extracts were significantly higher than PB. We also observed decreased ATP levels and increased mitochondrial depolarization in cells treated with both lines of feed with SB showing the greatest differences when compared to the control. This study provides evidence that irrespective of price, quality or marketing channels, pet foods present a high risk of mycotoxin contamination. Though in this study PB fared better than SB in regards to cell toxicity, there is a multitude of other factors that need to be studied which may have an influence on other negative outcomes.

Investigation of Salmonella contamination in dry dog foods marketed in Japan

Investigation of <i>Salmonella </i>contamination in dry dog foods marketed in Japan

Determination of Intrinsic Appearance Properties that Drive Dry Dog Food Acceptance by Pet Owners in Thailand

ABSTRACTConsumers and institutions make purchase and potential consumption decisions on behalf of other product users on a daily basis. Pet foods are one example of a product in that situation. The objective of this study was to determine what aspects of pet food appearance characteristics determine higher liking among Thai consumers. Consumers (n = 120) evaluated a total of 30 samples that varied in color, shape, size, and kibble composition. Information on overall liking, shape liking, size liking, and color liking was collected. Additional information was collected using a check-all-that-apply question regarding product characteristics. The results indicated that color and shape were important for Thai consumers; specifically, a yellowish color and bone shape were liked best. These results are important for pet food manufacturers and marketers in developing new products, as well as for product marketers in other consumer goods, such as child food, medications, food aid, and other divisions.

Validation of a Salmonella loop-mediated isothermal amplification assay in animal food

Loop-mediated isothermal amplification (LAMP) has emerged as a promising alternative to PCR for pathogen detection in food testing and clinical diagnostics. This study aimed to validate a Salmonella LAMP method run on both turbidimetry (LAMP I) and fluorescence (LAMP II) platforms in representative animal food commodities. The U.S. Food and Drug Administration (FDA)'s culture-based Bacteriological Analytical Manual (BAM) method was used as the reference method and a real-time quantitative PCR (qPCR) assay was also performed. The method comparison study followed the FDA's microbiological methods validation guidelines, which align well with those from the AOAC International and ISO. Both LAMP assays were 100% specific among 300 strains (247 Salmonella of 185 serovars and 53 non-Salmonella) tested. The detection limits ranged from 1.3 to 28 cells for six Salmonella strains of various serovars. Six commodities consisting of four animal feed items (cattle feed, chicken feed, horse feed, and swine feed) and two pet food items (dry cat food and dry dog food) all yielded satisfactory results. Compared to the BAM method, the relative levels of detection (RLODs) for LAMP I ranged from 0.317 to 1 with a combined value of 0.610, while those for LAMP II ranged from 0.394 to 1.152 with a combined value of 0.783, which all fell within the acceptability limit (2.5) for an unpaired study. This also suggests that LAMP was more sensitive than the BAM method at detecting low-level Salmonella contamination in animal food and results were available 3days sooner. The performance of LAMP on both platforms was comparable to that of qPCR but notably faster, particularly LAMP II. Given the importance of Salmonella in animal food safety, the LAMP assays validated in this study holds great promise as a rapid, reliable, and robust method for routine screening of Salmonella in these commodities.

A citizen‐trapper effort to control Common Myna: Trap success, specificity and preferred bait type

SummaryWe describe a community‐run effort to cull Common Myna (Acridotheres tristis) in Melbourne undertaken with modest funding (overall: $30.14 per trap day, $5.17 per euthanized Common Myna). Trap success (overall, 0.04 birds per trap per day) peaked early in the effort and slowly declined. Trap specificity was high (83.8%) and similar between bait types. Dry cat food captured more Common Myna, and a similar assemblage of animals, to dry dog food. Bread baits captured a broader assemblage of animals. The community‐led trapping programme reduced the mean density of Common Myna and achieved high target specificity with relatively few unintended trap deaths. While long‐term impacts on the population of Common Myna or native birds are yet to be analysed, the results suggest that ongoing effort is required for population suppression.

Sensory Characteristics and Volatile Components of Dry Dog Foods Manufactured with Sorghum Fractions.

Descriptive sensory analysis and gas chromatography-mass spectrometry (GC-MS) with a modified headspace solid-phase microextraction (SPME) method was performed on three extruded dry dog food diets manufactured with different fractions of red sorghum and a control diet containing corn, brewer’s rice, and wheat as a grain source in order to determine the effect of sorghum fractions on dry dog food sensory properties. The aroma compounds and flavor profiles of samples were similar with small differences, such as higher toasted aroma notes, and musty and dusty flavor in the mill-feed sample. A total of 37 compounds were tentatively identified and semi-quantified. Aldehydes were the major group present in the samples. The total volatile concentration was low, reflecting the mild aroma of the samples. Partial least squares regression was performed to identify correlations between sensory characteristics and detected aroma compounds. Possible relationships, such as hexanal and oxidized oil, and broth aromatics were identified. Volatile compounds were also associated with earthy, musty, and meaty aromas and flavor notes. This study showed that extruded dry dog foods manufactured with different red sorghum fractions had similar aroma, flavor, and volatile profiles.

Evaluation of canine adverse food reactions by patch testing with single proteins, single carbohydrates and commercial foods.

Adverse food reaction (AFR) is an important differential diagnosis for the pruritic dog. It is usually diagnosed by feeding an elimination diet with a novel protein and carbohydrate source for eight weeks followed by subsequent food provocation. A previous study demonstrated that patch testing dogs with foods had a high sensitivity and negative predictability for selection of elimination diet ingredients. The aim of this study was to investigate patch testing with proteins, carbohydrates and dry commercial dog food in dogs to determine whether there was value in patch testing to aid the diagnosis of canine adverse food reaction. Twenty five privately owned dogs, with confirmed AFR, underwent provocation trials with selected food antigens and patch testing. For proteins, carbohydrates and dry dog food the sensitivity of patch testing was 100%, 70% and 22.2%, respectively; the negative predictive values of patch testing were 100%, 79% and 72%. The positive predictive values of patch testing for proteins and carbohydrates were 75% and 74%, respectively. This study confirmed that patch testing may be useful for the selection of a suitable protein source for an elimination diet in dogs with suspected AFR, but not as a diagnostic tool for canine AFR. Results for proteins are more reliable than for carbohydrates and the majority of positive patch test reactions were observed with raw protein. Patch testing with commercial dog food does not seem to be useful.

Detection of DNA from undeclared animal species in commercial elimination diets for dogs using PCR.

Elimination diets are the gold standard for the diagnosis of adverse food reactions (AFR). A broad variety of commercial diets are available containing either hydrolysed protein or novel ingredients which claim to be suitable for elimination diets. Contamination may be one factor accounting for the failure of commercial elimination diet trials. To test commercial diets labelled as suitable for elimination diets for dogs, for DNA of animal origin other than that declared on the label. Twelve commercial dry and tinned dog food products were investigated for DNA of animal origin (chicken, turkey, beef, mutton and pork) using PCR testing. In nine of 10 over-the-counter diets, DNA of one or more animal species other than declared on the label was identified. The DNA most frequently detected was derived from beef (n = 8) and pork (n = 6). Two hydrolysed diets only contained DNA of the declared animal source. Over-the-counter "single protein diets" or canned meat products cannot be recommended for the diagnosis of dogs with AFR because contamination may cause the elimination diet to fail.

Impact of faecal DM excretion on faecal calcium losses in dogs eating complete moist and dry pet foods - food digestibility is a major determinant of calcium requirements.

The recommendations for the Ca supply for maintenance of dogs have been reduced by about 75% in the last decades. An important factor for Ca requirements is faecal Ca losses. In previous studies with experimental diets faecal Ca losses depended on Ca intake and on faecal DM excretion. A predictive equation for faecal Ca losses in mg/kg body weight (BW) developed in a fibre model is: faecal losses=-33·8+(13·6 faecal DM excretion (g/kg BW))+(0·78 Ca intake (mg/kg BW)). The present study aimed at testing this equation in pet food with material from trials carried out for other purposes. Digestion trials with twenty-five dry and fifteen moist foods (326 observations in total) were evaluated retrospectively. Faecal DM excretion and faecal Ca losses were significantly correlated (r20·86; P<0·001). There was a highly significant correlation (r20·87; P<0·001) between the experimentally determined faecal Ca excretion and the faecal Ca excretion predicted by the equation of Kienzle et al. The data from the previous fibre model study could be transferred to prepared moist and dry dog food. Faecal DM excretion has a considerable impact on faecal Ca losses in a practical feeding situation. In conclusion, Ca requirements for maintenance may vary with food DM intake and digestibility.

Effects of different protein sources on fermentation metabolites and nutrient digestibility of brachycephalic dogs.

Benefits to microbial fermentation in the colon and as a consequence less flatulence can be promoted for the health of adult dogs according to the amount and protein source. The present study evaluated different protein sources in dry food for brachycephalic dogs regarding microbial fermentation and nutrient digestibility. Four dry dog foods with similar protein content were formulated for adult maintenance: poultry meal (PM) diet; wheat gluten (WG) diet; PM+WG diet; and PM+WG+hydrolysed protein (HP) diet. Eight French bulldog adult dogs were arranged in a 4×4 Latin square design during the 28d trial. Fresh faeces were collected for assessment of nutrient digestibility and analyses of faecal pH, SCFA, biogenic amines, ammonia and lactate. Means were compared by the PROC MIXED procedure of SAS and by Tukey's test, considering P≤0·05. The animals fed the WG and PM+WG diets showed higher digestibility for DM (P<0·05), organic matter (P<0·05), crude protein (P<0·001) and lower faeces production (P<0·02) than the PM and PM+WG+HP diets. Feeding diet PM+WG+HP resulted in lower faecal score and pH (P<0·05) compared with other diets. Concentrations of fermentation metabolites were not statistically significantly different among diets. In conclusion, WG alone or in combination with PM improved protein and DM digestibility. Fermentation products were not affected by protein source.

Optimization of key aroma compounds for dog food attractant

Although several investigations devoted to dog food attractants (DFAs) have been conducted, these studies fell short in identifying the key aroma compounds that could improve the palatability performance of pet foods. The aim of this study was to identify the key aroma compounds in the DFA using headspace-solid phase micro-extraction, gas chromatography-mass spectrometry and Partial Least Squares Regression (PLSR) analysis. Seven DFAs with different aroma compounds obtained by Maillard reaction were employed in the study. A total of 53 aromatic compounds were identified categorized as follows: 7 alcohols, 11 aldehydes, 4 ketones, 4 organic acids, 7 esters, 2 ethers, 10 heterocycle compounds, 4 phenols, 2 terpenes and 2 polycyclic aromatic hydrocarbons. Eight adult beagle dogs were used for the preference test (two-pan test) and acceptance test (one-pan test) to rank these seven DFAs. PLSR was performed to correlate the instrumental data with the preference results. Twenty-three aroma compounds of hexanoic acid, acetaldehyde, heptanone, butyl hexanoate, heptyl formate, methyl pyrazine, 2,5-dimethyl pyrazine, 2-heptanone, pentanal, ethyl decanoate, heptanal, octanal, pentanol, acetone, ethyl caprylate, 3-methyl butanal, anisole, 2-ethyl hexanol, 2-pentyl furan, 2,3-butanediol, benzaldehyde, ethyl vanillin and vanillin correlated with the preference data. Benzaldehyde, vanillin and 2, 5-dimethyl pyrazine were added to dry dog foods in order to validate the PLSR results. The presence of three aroma compounds significantly increased the preferences of the samples (dry dog foods). The validation study involving the three compounds suggests that the 23 compounds selected by the PLSR model are aroma compounds which influence palatability. Therefore the manipulation of these flavor compounds could improve the palatability of dog foods.

Assessing the potential for Salmonella growth in rehydrated dry dog food

A substantial percentage of dog owners add water to dry dog food to increase its palatability. The recent association of Salmonella contamination of dry pet foods with salmonellosis cases in both dogs and their owners has generated a need to determine the ability of Salmonella to grow in eight commercial brands of rehydrated dry dog food. Eight brands of commercial dry dog food were rehydrated to 20, 35 and 50% added moisture, inoculated with two S. enterica strains (~105 CFU/g) and incubated for 72 h at 18 °C, 22 °C, or 28 °C. Dog food brand, moisture content, and temperature affected pathogen growth/survival patterns. Rehydration to 20% moisture did not support growth of S. enterica, and in general there was a 0.5–2.0 Log decline. At 35% moisture and 28 °C, 4 of 8 brands supported up to 3.4 Log(CFU/g) of growth, while Salmonella levels declined in three brands, and remained unchanged in one. Rehydration to 50% moisture at 28 °C supported increases of up to 4.6 Log(CFU/g) in 5 of 8 brands. Growth kinetics determinations with two of the brands that supported growth had calculated lag times, generation times, and maximum population densities of 4.4 and 2.2 h, 1.4 and 10.8 h, and 7.3 and 6.9 Log(CFU/g) when rehydrated to 35% moisture and held at 30 °C. Results of this study establish that the rehydration of dry dog food with sufficient amounts of water may support the growth of S. enterica. Based on the most rapid observed lag times, growth of Salmonella, if present, in rehydrated dog food could be avoided by discarding or refrigerating uneaten portions within 2–3 h of rehydration. These data allow accidental or intentional rehydration of dry dog food to be factored into predictive microbiology models and exposure assessments.

Mercury concentrations in wet and dry cat and dog food

Given that mercury (Hg) concentrates in fish, and this is an important ingredient in pet food, we hypothesized that Hg concentrations could be of concern. To address this hypothesis, total Hg concentrations were measured in a variety of brands of cat (n=47) and dog (n=54) food. Since most of the Hg in fish is methylmercury, we assume that this is the form in the pet food. However, this still needs to be tested. Mercury concentrations ranged from 1 to 604ngg−1. There are no standards for pet food, so values were compared to available consumption advisories: 300–1000ngg−1 for humans, 30ngg−1 for kingfishers (fish eating birds), small mammals (70ngg−1), and river otters (100ngg−1). Thirty one of the pet food samples had concentrations >30ngg−1, and 14>100ngg−1. More studies are necessary to understand the health implications of Hg concentrations observed.