Concentrations of macronutrients, minerals and heavy metals in home-prepared diets for adult dogs and cats

Individual and combined contamination of the toxic metals in commercial cat and dog food

As the long-term accumulation of toxic metals in food poses significant health risks to pets, there is a growing concern among people regarding toxic metal contamination in pet food. In order to investigate the toxic metals levels in pet food in China, we collected a total of 93 imported cat and dog food from the Chinese market produced in 2021-2022, comprising 45 cat food and 48 dog food, and determined the concentrations of lead (Pb), cadmium (Cd), chromium (Cr), mercury (Hg) and arsenic (As) in them. The concentrations of Pb, Cd and Cr were determined by flame atomic absorption spectrometry, while Hg and As were quantified by atomic fluorescence spectrometry. The most contaminated of all samples were Cr and As, which were detected in all samples, followed by Hg, which was detected in 91 samples. In cat food, Cr and As were the most prevalent toxic metals, and Cr and Hg were found in all dog food. Pb was not detected in the canned food, while both cat and dog canned foods showed relatively high contamination rates of Cr, As, and Hg. Cr, Hg and As had the highest contamination levels in dry food. Some samples exceed the limits set by Hygienical Standard for Pet Feed of China (Announcement No. 20 of 2018) regarding Pb and Cr, while other toxic metals remained within acceptable limits. Canned food, however, met all regulatory limits for toxic metals. Across all types of pet food, Cr, Hg, and As were consistently the most prevalent combined contaminants. Analysis of the acute hazard index (aHI) values showed that both cats and dogs face potential dietary exposure risks to the toxic metals investigated, with Cr posing the most significant risk, followed by Pb and As. This study underscores the extensive presence of toxic metal contamination in pet foods, posing a significant risk to pet health due to ongoing exposure to multiple toxic metals.

Elements in trace amount with a significant role in human physiology: a tumor pathophysiological and diagnostic aspects

Cancer has a devastating impact globally regardless of gender, age, and community, which continues its severity to the population due to the lack of efficient strategy for the cancer diagnosis and treatment. According to the World Health Organisation report, one out of six people dies due to this deadly cancer and we need effective strategies to regulate it. In this context, trace element has a very hidden and unexplored role and require more attention from investigators. The variation in concentration of trace elements was observed during comparative studies on a cancer patient and a healthy person making them an effective target for cancer regulation. The percentage of trace elements present in the human body depends on environmental exposure, food habits, and habitats and could be instrumental in the early diagnosis of cancer. In this review, we have conducted inclusive analytics on trace elements associated with the various types of cancers and explored the several methods involved in their analysis. Further, intricacies in the correlation of trace elements with prominent cancers like prostate cancer, breast cancer, and leukaemia are represented in this review. This comprehensive information on trace elements proposes their role during cancer and as biomarkers in cancer diagnosis.

Ketogenic diets: A systematic review of current scientific evidence and possible applicability in dogs and cats

Ketogenic diets (KD) have been used in the treatment of epilepsy in humans for around a century and, more recently, they have been implanted for cancer patients, as well as in the treatment of obesity. This type of diet consists of high-fat levels, an adequate amount of protein and restricted carbohydrates, or high medium-chain triglycerides. Recently, the ketogenic diet has gained attention in veterinary medicine and studies were published evaluating the effects of KD in dogs with epilepsy. The objective of this review was to highlight recent studies about the application of KD in dogs and cats, to describe the neurobiochemical mechanisms through which KD improves epilepsy crisis, and their adverse effects. Studies were identified by a systematic review of literature available on PubMed, Embase, and Scopus. All cohort and case-control studies were included, and all articles were exported to Mendeley® citation manager, and duplicates were automatically removed. Seven articles and three conference abstracts conducted with dogs were included in the present study. There is evidence that the consumption of diets with medium-chain triglycerides increases the concentration of circulating ketone bodies and improves epilepsy signs, although these diets have higher carbohydrate and lower fat content when compared to the classic KD.

What Is the Cost of Weight Loss? An Approach to Commercial (Dry and Wet) and Homemade Diets

In the context of the rising prevalence of obesity among pets, this study aimed to assess the economic aspects of weight reduction protocols for dogs and cats, considering the lack of information and the varying costs of commercial and homemade diets. The results indicated an average weekly weight loss rate of 1.02% for dogs and 0.92% for cats, with a reduction in body fat mass (p < 0.005). The cost analysis included an evaluation of both dry and wet commercial prescription diets as well as homemade diets. The results unveiled higher expenses associated to wet commercial diets, followed by homemade and dry commercial diets (p < 0.001). The study demonstrated that despite the initial investment, the long-term benefits of weight loss, including improved health and reduced financial burdens for owners, justify the expenses incurred. This comprehensive analysis provides veterinarians and pet owners with valuable insights into the economic considerations of weight reduction protocols, facilitating informed decision making and promoting pet well-being.

Nutritional evaluation of new alternative types of dog foods including raw and cooked homemade-style diets

BACKGROUND

New alternative types of pet foods such as raw and cooked homemade-style diets containing human food ingredients have been introduced due to a trend of pet humanization and diversification of consumer needs.

OBJECTIVES

To evaluate nutritional adequacy of new alternative types of dog foods containing human food ingredients as maintenance diets for dogs.

METHODS

Eleven homemade-style foods for adult dogs were purchased from online channel in Korea and analyzed to evaluate nutritional adequacy for adult dogs. Nutrients analyzed included crude protein, amino acids, crude fat, fatty acids, and minerals.

RESULTS

Crude protein and amino acids in all products satisfied Association of American Feed Control Officials (AAFCO) requirements. Crude fat in one of 11 products did not meet AAFCO requirements. The most deficient minerals were selenium (10 of 11, 90.9%), copper (five of 11, 45.5%), zinc (five of 11, 45.5%), potassium (three of 11, 27.3%), calcium (three of 11, 27.3%), iron (two of 11, 18.2%), and magnesium (one of 11, 9.1%). Six products were not in the range of the recommended Ca:P ratio in AAFCO dog food maintenance nutrient profiles.

CONCLUSIONS

This study performed nutritional evaluation of raw and cooked homemade-style foods as maintenance diets for adult dogs. Some nutritional inadequacies were observed including some minerals, Ca:P ratio, and omega-6:omega-3 fatty acid ratio, although three products (26.2%) satisfied the AAFCO standard except selenium. Overall, the data suggest a need for accurate nutritional adequacy statement for consumers based on proper methods to validate the formula.

The Impact of Fetal Programming in Ewe Nutrition with Chromium Propionate or Calcium Salts of Palm Oil on the Meat Quality and Bone of the Progeny

This study aimed to evaluate the inclusion of chromium propionate or calcium salts of palm oil in ewes' diet during the final third of gestation and lactation on progeny performance, carcass characteristics, non-carcass components, and bone density. Forty-three ewe, Santa Inês and Dorper breed, three ± one-year-old, and body weight 57 ± 10 kg were used. The experimental design was in casual blocks in three treatments, CTL treatment (n = 15) with starch from corn; CR (n = 15) diet CTL plus chromium propionate; PF (n = 13) diet CTL plus calcium salts of palm oil. After weaning, 23 male lambs from these ewes were confined in individual stalls, with the same diet for 60 days, slaughtered. The data were analyzed using the SAS program, PROC GLM, and compared the means using Tukey's test at 5% probability. The maternal diet did not alter the dry matter intake, feeding efficiency, and average daily weight gain. Therefore, weights (weaning and slaughter) and carcass yield were higher for CR and PF groups than for CTL (P < 0.05). The treatment did not influence the loin eye area and fat thickness (P > 0.05). The spleen and the respiratory tract were smaller for PF and larger for CTL (P < 0.05). Leg weight was higher for CR. The perimeter and depth of the shank for the CR and PF lambs were higher, indicating an effect of maternal nutrition in this commercial cut. The CR group had a smaller epiphysis measurement and femur length than the CTL group. We concluded that the fetal programming effect in ewes fed with Cr propionate and Ca salts of palm oil benefited the progeny by increasing their body weight, better carcass yield, and a higher proportion of prime cuts.

Domestic dogs as sentinels of children lead exposure: Multi-pathway identification and source apportionment based on isotope technique

Environmental lead exposure poses risks to children' health, thus exposure sources and pathways identification remain important concern and research scope. Due to sharing the same environment, domestic animals, especially dogs, have been used as useful sentinels to identify human lead exposure. However, more evidence is needed on whether domestic dogs could be used to identify the lead exposure pathways and sources of children. Thus, this study investigated the dietary habits, behaviors, and household environment of children and dogs in a typical coal-fired area in China. The lead levels and lead isotope ratios (Acronym: LIRs, expressed as ²⁰⁸Pb/²⁰⁶Pb and ²⁰⁷Pb/²⁰⁶Pb) in dogs' and children's blood, as well as in environmental media (food, PM_2.5, indoor/outdoor dust, drinking water and soil) were measured to explore the predominant lead pollution sources and exposure pathways of children. The results showed that the LIRs of children's blood (²⁰⁸Pb/²⁰⁶Pb = 2.0703 ± 0.0076, ²⁰⁷Pb/²⁰⁶Pb = 0.8501 ± 0.0052) were similar to those of dogs' blood (²⁰⁸Pb/²⁰⁶Pb = 2.0696 ± 0.0085, ²⁰⁷Pb/²⁰⁶Pb = 0.8499 ± 0.0052), as well as similar to the LIRs of environmental media, i.e. children's food (²⁰⁸Pb/²⁰⁶Pb = 2.0731 ± 0.0057, ²⁰⁷Pb/²⁰⁶Pb = 0.8491 ± 0.0036) and coal (²⁰⁸Pb/²⁰⁶Pb = 2.0683 ± 0.017, ²⁰⁷Pb/²⁰⁶Pb = 0.8515 ± 0.01). Children and dogs had similar lead exposure pathways, but the contributions of each exposure pathway were different, i.e., 83.1% vs. 76.9% for children and dogs via food ingestion, 1.4% vs. 5.6% via particulate matter exposure, and 15.5% vs. 17.5% via household dust exposure, respectively. The contribution of food via ingestion to lead exposure remains dominant, and coal combustion is a main lead exposure source for children and domestic dogs.

Relationships between the Content of Micro- and Macroelements in Animal Samples and Diseases of Different Etiologies

Many of the micro- and macro-elements (MMEs) required by the body are found in environmental objects in concentrations different from their original concentration that can lead to dangerous animal diseases ("microelementoses"). The aim was to study the features of MME (accumulating in wild and exotic animals) in connection with particular diseases. The work using 67 mammal species from four Russian zoological institutions was completed in 2022. Studies of 820 cleaned and defatted samples (hair, fur, etc.) after "wet-acid-ashing" on an electric stove and in a muffle furnace were performed using a Kvant-2A atomic absorption spectrometer. The content of zinc, copper, iron, cadmium, lead, and arsenic was assessed. The level of MME accumulation in the animal body contributes not only to the MME status and the development of various concomitant diseases, but the condition itself can occur by intake of a number of micronutrients and/or drugs. Particular correlations between the accumulation of Zn and skin, oncological diseases, Cu-musculoskeletal, cardiovascular diseases, Fe-oncological diseases, Pb-metabolic, nervous, oncological diseases, and Cd-cardiovascular diseases were established. Therefore, monitoring of the MME status of the organism must be carried out regularly (optimally once every 6 months).

Zinc Concentration in Blood Serum of Healthy Dogs

The objective of this study was to establish a reference interval for serum zinc in dogs and to determine the factors that affected it. We collected samples from 197 clinically healthy animals of various breeds and ages and obtained information about their sex, neuter status, age, breed, diet, lifestyle, weight, and body condition score. Serum zinc concentration was measured by a colorimetric method using a clinical chemistry analyzer. We established the reference interval for serum zinc as 4.9-19.7 µmol/L. When assessing the relationship of zinc with various biochemical parameters, we found significant correlation with albumin and triacylglycerols. The only observed factor that significantly influenced serum concentration was sex. Female dogs had higher levels (median 11.0 µmol/L) than males (median 8.9 µmol/L). The difference between intact females and intact males was also significant (medians 11.6 and 9.0 µmol/L respectively), but it was only numerical for neutered animals (median of neutered females 10.7 µmol/L and of neutered males 8.7 µmol/L). Despite the general belief that homemade food for dogs contains a lower amount of zinc than a commercial one, diet did not influence zinc serum levels significantly. There was also no impact of age, breed, lifestyle, weight, or body condition score on serum zinc concentration.

Home-cooked diets cost more than commercially prepared dry kibble diets for dogs with chronic enteropathies

OBJECTIVE

Nutrition plays a fundamental role in the management of canine chronic enteropathies (CCEs). Dog owners may elect to feed home-cooked diets (HCDs) rather than veterinary commercially prepared diets (CPDs) because of perceived lower costs. There is a paucity of data comparing costs of these options. We hypothesize there will be differences in costs between complete and balanced HCDs and nutritionally comparable CPDs.

SAMPLE

6 Home-cooked diets.

PROCEDURES

Six HCD recipes (2 highly digestible, 2 limited antigen, 2 low-fat) were formulated by 2 board-certified veterinary nutritionists to mimic the nutritional and ingredient profiles of veterinary CPDs for management of CCEs. The cost (in US$ on a per 100 kilocalorie [kcal] basis) of each recipe was determined via collection of ingredient prices from 3 grocery stores combined with supplement prices from online retailers. Prices of CPDs were obtained from a national online retailer. Maintenance energy requirements of 1.6 X (70 X BWkg0.75), where BWkg represents body weight in kilograms, were calculated for 3 dog sizes (5, 20, and 40 kg), and costs of feeding maintenance energy requirements with HCDs versus dry and canned CPDs were compared with a Kruskal-Wallis test and post hoc testing.

RESULTS

The median costs of all dry and canned CPDs and HCDs were $0.29 (range, $0.18 to $0.46), $1.01 (range, $0.77 to $1.20), and $0.55 (range, $0.35 to $1.14), respectively. Feeding complete and balanced HCDs cost more than feeding dry CPDs (P < .001), but not canned CPDs (P > .99).

CLINICAL RELEVANCE

Dry CPDs cost the least for nutritional management of CCEs. There is a wide range of costs for both CPDs and HCDs.

Influence of a Polyherbal Choline Source in Dogs: Body Weight Changes, Blood Metabolites, and Gene Expression

Choline chloride is used to provide choline in dog foods; however, in other domestic species, it has been replaced with a polyherbal containing phosphatidylcholine. A polyherbal containing Achyrantes aspera, Trachyspermum ammi, Citrullus colocynthis, Andrographis paniculata, and Azadirachta indica was evaluated in adult dogs through body weight changes, subcutaneous fat thickness, blood metabolites, and gene expression. Forty dogs (4.6 ± 1.6 years old) who were individually housed in concrete kennels were randomly assigned to the following treatments: unsupplemented diet (377 mg choline/kg), choline chloride (3850 mg/kg equivalent to 2000 mg choline/kg diet), and polyherbal (200, 400, and 800 mg/kg) for 60 days. Blood samples were collected on day 59 for biochemistry, biometry, and gene expression analysis through microarray assays. Intake, final body weight, and weight changes were similar for the two choline sources. Feed intake variation among dogs (p = 0.01) and dorsal fat (p = 0.03) showed a quadratic response to herbal choline. Dogs that received the polyherbal diet had reduced blood cholesterol levels (Quadratic, p = 0.02). The gene ontology analysis indicated that 15 biological processes were modified (p ≤ 0.05) with implications for preventing cardiovascular and metabolic diseases, cancer prevention, inflammatory and immune response, and behavior and cognitive process. According to these results that were observed in a 60 day trial, the polyherbal form could replace choline chloride in dog diets at a concentration of 400 mg/kg.

Comparison of canine owner profile according to food choice: an online preliminary survey in France

Background

Nowadays, more people are treating dogs as family members. This reflects their increased attention towards their nutrition, with renewed interest for non-conventional diets such as Biologically Appropriate Raw Food/ Bones and Raw Food in United States (BARF) or homemade. In previous studies, owners feeding their dog non-conventional diets reported lower levels of trust in veterinary advice. The aim of the study was to identify differences in lifestyle between owners feeding dogs non-conventional diets and those feeding conventional diets (i.e., dry/wet pet food) to give further insight for improving communication between veterinarians and owners.

Results

A total of 426 surveys were usable. Fifteen percent of the participants lived in the metropole of Paris and had more than one dog (mean 1.72 dogs). Thirty-eight percent of the survey respondents stated that their dogs were fed exclusively with non-conventional diets, while 55% declared using conventional diets alone (not considering treats). The study canine population was for the most part neutered (63%) and purebred (68%). Amongst owners feeding conventional diets exclusively, 47% determined how much food to feed by consulting the feeding guidelines on the packaging, and only 28% said that the amount of food was prescribed by their veterinarian or veterinary nurse. Out of the participants feeding non-conventional diets, 65% declared that the information for formulating the recipes was gathered on the internet or in non-veterinary books. When compared with owners feeding exclusively conventional diets, those feeding non-conventional diets were living more frequently outside the metropole of Paris, had fewer children (0.23 ± 0.57 vs 0.37 ± 0.78; p = 0.03) and had more frequently other animals. They also dewormed less often their pets, walked their dog more each day (91 vs 78%; p < 0.001) and without leash for more than 6 h per week (46 vs 31%; p = 0.003).

Conclusions

This survey described differences in the habits of owners feeding dogs non-conventional diets in comparison with those feeding conventional diets. Data suggest that owners using non-conventional diets may be more attentive to the ethological needs of their dog which could be a starting point for practitioners for achieving better client-veterinarian communication.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03258-9.

Evaluation of the nutrients supplied by veterinary diets commercialized in Brazil for obese dogs undergoing a weight loss program

During a weight loss program, energy restriction is performed, which can result in nutrient intake below the minimum recommendations if a proper diet is not offered. A common recommendation for dogs undergoing energy restriction is to use a veterinary diet formulated for the management of obesity to potentially reduce the likelihood of nutritional deficiencies. The objective of this study was to perform bromatological and essential mineral analysis in veterinary diets for the management of canine obesity available in the Brazilian market and to analyse whether these diets provide the recommended amount of nutrients per kg of metabolic body weight (kg BW^0.75 ) for animals undergoing energy restriction. Samples of all veterinary diets for the management of canine obesity available in the Brazilian pet food market were analysed (n = 8). The nutrient supply per kg BW^0.75 was calculated and compared with the NRC recommended allowance and FEDIAF recommendations by descriptive statistics. For this purpose, the weight loss energy requirement equations of 70 kcal/target body weight^0.75 and 63 kcal/target body weight^0.75 were used, in which target body weight corresponds to 10%-40% of the initial body weight according to the body condition score. The manufacturers' intake recommendations were also evaluated and compared to the NRC and FEDIAF recommendations. Almost all of the diets (n = 7/8) had at least one nutrient below the NRC and FEDIAF recommendations when target weight of minus 10%, 20% or 30% was considered, and all diets had at least one nutrient deficiency when the target weight was minus 40%. When the energy intake was restricted a further 10%, all diets had at least one nutrient below recommendations at the minus 30% target weight. The nutrients for which the recommendations were not met were as follows: calcium, magnesium, potassium, selenium, sodium, protein and fat. When compared to the manufacturers' recommendations, nutrient deficiencies were observed in all of the diets when compared to the NRC and in 7/8 when compared to FEDIAF, and all diets had at least one deficiency when compared to both NRC and FEDIAF after an extra 10% calorie restriction. It was concluded that the majority of veterinary diets formulated for weight loss/obesity management in Brazil did not meet all the recommendations of the analysed nutrients, which reinforces that diets for weight loss should be used according to veterinary prescription and should ideally be prescribed by nutrition specialists that can better understand the limitations of the diet's composition.

Dietary management of chronic enteropathy in dogs

Chronic idiopathic enteropathy is a clinical condition defined by the exclusion of infectious, metabolic or neoplastic causes of gastrointestinal signs and is categorised by a response to treatment including management with diet change, immunosuppressant medication or interventions that directly target the microbiome (e.g. antibiotics, faecal transplantation or probiotics). Animals that fail these therapies are categorised as non-responsive or refractory chronic idiopathic enteropathy. This specific categorisation implies that nutritional intervention is only needed for a subset of patients with enteropathy. However, often dogs with chronic idiopathic enteropathy are malnourished, have nutrient malabsorption or have gastrointestinal inflammation that occurs as a result of a breakdown in tolerance to luminal antigens including microorganism or dietary components. Thus, all dogs with chronic idiopathic enteropathy benefit from a nutritional assessment and targeted nutritional intervention. Among dogs presenting for chronic idiopathic enteropathy, the response rate to diet alone is roughly 50% in the referral population giving the impression that the overall response could be even higher especially when more than one nutritional intervention is attempted and strict adherence is maintained. The objectives of this review article are to outline the nutritional approach to a dog with chronic idiopathic enteropathy, including the nutritional assessment, and to highlight areas for nutritional intervention.

Influence of number of ingredients, use of supplement and vegetarian or vegan preparation on the composition of homemade diets for dogs and cats

Background

Homemade diets are a worldwide trend, and many recipes are currently available on websites but may not be considered balanced. This study aimed to evaluate if the number of ingredients, supplement, or vegetarian/vegan-only ingredients included in a recipe influence the nutrient content of homemade diets for dogs and cats. Chemical analyses were performed on 75 diets for dogs and 25 for cats prepared according to websites’ recipes, and minerals were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES).

Results

Canine diets that met fat requirements had more ingredients than those below recommendations. None of the cat diets met iron requirements, and feline diets that met requirements of manganese had fewer ingredients and those that supplied requirements of protein and sodium had more ingredients than the diets below recommendations (p < 0.05). Non-supplemented canine and feline diets had calcium and calcium:phosphorus ratio below recommendations (p < 0.05). Non-supplemented feline diets had lower sodium and iron, and zinc levels were below recommendation in diets for both species. Diets with animal products for dogs had higher levels of protein and zinc, although zinc was deficient in both groups, and there were higher amounts of crude fiber, magnesium, and manganese in vegetarian/vegan diets (p < 0.05). Diets with animal products for cats had higher levels of protein (p = 0.003), but there was a higher amount of crude fiber (p = 0.014) in vegetarian/vegan diets.

Conclusion

The number of ingredients and vegetarian/vegan preparation did not guarantee nutritional adequacy of diets, and the presence of supplement did not ensure a balanced diet.

Diet and dog characteristics affect major and trace elements in hair and blood of healthy dogs

Obtaining correct amounts of essential elements, and avoiding toxic metals are key factors in dog health. Through analyzing major and trace elements in hair and blood of 50 healthy companion dogs using ICP-MS, we study their associations with dog characteristics and diet, hypothesizing that eating the same diet long-term results in strong correlations between hair and blood element concentrations, and that dog characteristics and diet affect element status. The correlation between hair and blood was significant for Hg (R = 0.601, p = 0.000) and Pb (R = 0.384, p = 0.010). The following associations were significant (p < 0.05): Dark hair had higher Ca and Mg compared to light hair. Females had higher hair Zn, blood Mn, and blood As compared to males. Blood Mn and Se increased, while blood Pb decreased with age. Raw diet fed dogs had higher hair Zn and Se compared to dry or mixed diet fed dogs, and lower blood Mn compared to dry diet fed dogs. Dry and mixed diet fed dogs had higher blood Cd compared to raw diet fed dogs. Mixed diet fed dogs had higher hair Ca and Mg compared to raw or dry diet fed dogs, and higher hair Pb compared to dry diet fed dogs. Wild game consumption was associated with higher blood Pb, and rice consumption with higher blood As. In conclusion, hair provides an alternative for assessing Hg and Pb exposure, and major and trace elements status is affected by hair color, sex, age, and diet.

Toxic element levels in ingredients and commercial pet foods

Nowadays, there is a growing concern about contamination of toxic metals (TM) in pet food due to the great potential for health risks of these elements. TM concentrations in commercial pet foods (n = 100) as well as in ingredients used in their composition (n = 100) were analyzed and compared to the Food and Drug Administration (FDA) maximum tolerable level (MTL), and the TM concentrations found in the different sources of carbohydrate, protein, and fat were compared. The TM concentrations were determined by inductively coupled plasma with optical emission spectrometry (ICP-OES). Concentrations above the MTL for aluminum, mercury, lead, uranium, and vanadium were observed in both dog and cat foods, and the percentage of dog foods that exceeded the MTL of these TM were: 31.9%; 100%; 80.55%; 95.83%; and 75%, respectively, and in cat foods: 10.71%; 100%; 32.14%; 85.71%; 28.57%, respectively. The MTL values of these TMs and the mean values in dog foods (mg/kg dry matter basis) (MTL [mean ± standard deviation]) were: aluminum: 200 (269.17 ± 393.74); mercury: 0.27 (2.51 ± 1.31); lead: 10 (12.55 ± 4.30); uranium: 10 (76.82 ± 28.09); vanadium: 1 (1.35 ± 0.69), while in cat foods were: aluminum: 200 (135.51 ± 143.95); mercury: 0.27 (3.47 ± 4.31); lead: 10 (9.13 ± 5.42); uranium: 10 (49.83 ± 29.18); vanadium: 1 (0.81 ± 0.77). Dry foods presented higher concentrations of most TM (P < 0.05) than wet foods (P < 0.05). Among the carbohydrate sources, there were the highest levels of all TM except cobalt, mercury, and nickel in wheat bran (P < 0.05), while among the protein sources, in general, animal by-products had higher TM concentrations than plant-based ingredients. Pork fat had higher concentrations of arsenic, mercury, and antimony than fish oil and poultry fat. It was concluded that the pet foods evaluated in this study presented high concentrations of the following TM: aluminum, mercury, lead, uranium, and vanadium.

Using a next-generation sequencing approach to DNA metabarcoding for identification of adulteration and potential sources of mercury in commercial cat and dog foods

Studies have demonstrated that some commercial pet (i.e., cat and dog) food products contain high concentrations of mercury (Hg), and some products have Hg concentrations that are higher than expected based on the ingredients included in the package ingredient list. Additionally, concentrations of methylmercury, a particularly toxic form of Hg commonly associated with fish-based ingredients, are largely unstudied despite the widespread use of such ingredients in pet food products. This study aimed to quantify total Hg and methylmercury in a variety of commercial pet food products (n = 127), and use genetic tools to determine if specific ingredients contributed to high Hg concentrations in the final product. Results indicate that total Hg concentrations were above suggested maximum tolerable limits in three of the tested pet food products, and that methylmercury concentrations were at safe levels in all tested products. Next-generation amplicon sequencing using ten barcode primers was conducted to target distinct taxa and to determine if one primer set outperformed the others in amplifying the often heavily degraded DNA found in pet food products. The 16sUniF_16sUniR primer set generated a relatively higher number of reads across the broadest set of taxa, although several of the primer sets were useful in identifying common animal- and plant-based ingredients in commercial pet food products. Combined with the Hg results, it was demonstrated that pet food product ingredients are consistent among and between product lots. However, these results also revealed that adulteration is prevalent in pet food products.

Computer-aided ration calculation (Diet Check Munich© ) versus blood profile in raw fed privately owned dogs

Many dog owners create nutritionally imbalanced raw meat-based diets (RMBD) with information from the Internet and pseudo-scientific books, some even use pre-prepared frozen raw feed from online shops, local butchers or other providers. The risk of nutritional imbalances is therefore present. Blood profiles for dogs fed RMBD are promoted by laboratories as a simple tool for the owner to check the nutritional supply situation. Veterinarian nutrition specialists seem to be consulted less frequently and, in most cases, when blood analyses show deviations from reference ranges. The aim of the present study was to evaluate whether a RMBD blood profile reflects possible malnutrition according to a computer-aided ration check and to assess its clinical relevance. Using standardized questionnaires, the average daily rations of 104 dogs, 83 of which were fed raw diets versus 21 commercially fed dogs, were analysed using Diet Check Munich©, based on the National Research Council values. Afterwards, the SYNLAB.vet GmbH 'Barfer-Profil' test including calcium, phosphate, calcium/phosphate ratio, vitamin A, vitamin D, copper, zinc and iodine with additional parameters taurine, urea, uric acid and creatinine was carried out. No significant correlation between nutrient supply and associated blood parameters could be detected. Diet calculation revealed significantly more nutritional imbalances in the RMBD group than in the control group. Low plasma taurine could be detected only in the RMBD group. After participating, 30% of the dog owners (RMBD group) decided to adjust their dogs' diets at the nutrition consultation of the Clinic for Small Animal Internal Medicine of the LMU Munich. Based on these results, for most parameters a RMBD blood profile is not an appropriate tool to monitor a dog's nutrition and computer-aided ration calculation remains the gold standard for detecting nutritional imbalances.

Clinical health markers in dogs fed raw meat-based or commercial extruded kibble diets

The interest and demand for healthy and less processed foods for human consumption have been mirrored in the pet industry, with an explosion of alternative diets available. Several nontraditional feeding methodologies including raw meat-based diets (RMBDs) are believed by many dog owners to be superior to traditional extruded commercial dog foods. Despite the strong opinions, limited data are available comparing objective health measures among healthy dogs fed using different methods of diet preparation. Therefore, we compared health markers in client-owned dogs fed an RMBD to markers in dogs fed a high-quality extruded kibble. We hypothesized that healthy adult dogs fed RMBD would show differences in biochemical and hematological parameters and improved clinical health scores (e.g., dental, external ear canal, and integument scores) compared with dogs fed a kibble diet. A cross-sectional observational study was performed comparing hematology, serum biochemistry, urinalysis management history, and clinical health scores in healthy client-owned dogs reported as fed RMBD (n = 28) or kibble (n = 27) for >1 yr. Dental, external ear canal, and integument health scores were assigned by a single veterinary evaluator blinded to feed group, using a scale where 0 was normal and 3 was most severely affected. Spearman correlation coefficient (rs) was calculated to assess the strength and direction of the relationship of biochemical outcomes with age and body condition score (BCS), while analysis of variance was used to determine if biochemical analytes differed by breed or gender. Biochemical data were analyzed using multiple linear regression models, adjusting for the covariates gender, breed, age, and BCS. A composite clinical health score, (CCS) = 9 - (dental score + otitis score + integument score), was compared between feeding groups using Mann-Whitney test. Serum alkaline phosphatase activity (P < 0.001) and globulin concentration (P < 0.001) were lower, while lymphocyte count (P < 0.05) was higher in dogs fed RMBD. No differences were found in urinalysis between diet groups. Dogs fed RMBD showed a slight improvement in CCS compared with kibble-fed dogs (CCS: P = 0.03). Owner management significantly differed with a greater likelihood of management interventions including dietary supplements and sporting activities in the RMBD group. Further work is needed to specifically determine the impact of diet processing and nutrient content on canine health.

Nutritional Evaluation and Risk Assessment of the Exposure to Essential and Toxic Elements in Dogs and Cats through the Consumption of Pelleted Dry Food: How Important Is the Quality of the Feed?

Dry feed for pets lacks specific legislation regarding maximum residue limits for inorganic elements. The aim of the present study was to determine the content of 43 inorganic elements in dog and cat feed, studying whether there were differences according to the supposed quality of the food and performing the risk assessment for health. Thirty-one and thirty packages of pelleted dry food for cats and dogs, respectively, were analyzed. After acidic microwave-assisted digestion, elements were detected and quantified by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). In general, we did not observe important differences in the content of elements according to the supposed quality of the brand. Among trace elements, selenium and manganese are above the dietary reference value. Arsenic and mercury showed the highest acute hazard indexes, which make them risk factors for the health of dogs and cats. Aluminum, uranium, antimony and vanadium contents were above the toxic reference value and showed the highest acute hazard indexes. It is necessary to improve the legislation regarding the food safety of pets, for their health and to protect the rights of consumers.

Vitamin-mineral supplements do not guarantee the minimum recommendations and may imply risks of mercury poisoning in dogs and cats

Given the importance of using the vitamin-mineral supplements to guarantee the minimum nutritional recommendations for pets in homemade foods, and hypothesizing that these products may contribute to toxic metals contamination, the present study aimed to determine the concentrations of essential minerals and toxic metals in vitamin-mineral supplements available in the Brazilian market and calculate if the amount recommended by the manufacturer guarantees the minimum recommendations of NRC (2006) and FEDIAF (2020), as well as calculating the amount of toxic metals that animals would consume, according to the amounts recommended by the manufacturer. Seven vitamin-mineral supplements were analyzed. The determination of essential minerals and toxic metals was performed using ICP-OES. Comparisons were made with the minimum recommendations for essential minerals, and with the maximum tolerated levels of toxic metals established by the FDA (2011), descriptively. Most of the vitamin-mineral supplements, in the quantities recommended by the manufacturers, do not guarantee the minimum recommendations of NCR (2006) and FEDIAF (2020) for the following elements: calcium, potassium, magnesium, sodium, phosphorus, selenium, and zinc. Only one supplement had detectable selenium concentrations. Three supplements provided more than 0.02mg of mercury/kg of body weight, the safe upper limit used to establish the maximum tolerated level of this element. It is concluded that most vitamin-mineral supplements do not meet the minimum recommendations for most essential minerals and, if formulated by untrained professionals, even with supplementation, homemade foods may still be nutritionally deficient. Furthermore, some vitamin-mineral supplements analyzed may imply risks of mercury poisoning in pets.

Zinc in Dog Nutrition, Health and Disease: A Review

Simple Summary

This work compiles the current state of knowledge regarding zinc requirements of healthy dogs and biomarkers of zinc status. To ensure an adequate zinc status, it is important to know the zinc content of foods and their bioavailability to assess the need and the ideal supplementation strategy regarding levels and sources of additives in complete dog foods. As zinc is required for enzymatic, structural, and regulatory functions in the animal body, its nutritional status has been associated with several pathologies that may be due to, or exacerbated by, a deficit of dietary zinc supply.

Abstract

Zinc is an essential trace element, required for enzymatic, structural, and regulatory functions. As body reserves are scarce, an adequate zinc status relies on proper dietary supply and efficient homeostasis. Several biomarkers have been proposed that enable the detection of poor zinc status, but more sensitive and specific ones are needed to detect marginal deficiencies. The zinc content of commercial dry dog foods has great variability, with a more frequent non-compliance with the maximum authorized limit than with the nutritional requirement. The bioavailability of dietary zinc also plays a crucial role in ensuring an adequate zinc status. Despite controversial results, organic zinc sources have been considered more bioavailable than inorganic sources, albeit the zinc source effect is more evident after a restriction period of dietary zinc. Many disorders have been associated with inadequate zinc status, not being clear whether the occurrence of the disease is the consequence or the cause. This review presents data on zinc requirements and biomarkers for zinc status, that can be applied for the development of supplementation strategies of zinc in complete pet foods. Moreover, it provides an understanding of the role zinc plays in the health of dogs, and how altered zinc status affects diseases in dogs.

Mineral Composition of Cereal and Cereal-Free Dry Dog Foods versus Nutritional Guidelines

The aims of the present work are to estimate the nutritional value and to evaluate and compare the levels of macroelements (Ca, P, K, Na, Mg), microelements (Fe, Zn, Mn, Cu), heavy metals (Co, Cd, Pb, Mo, Cr, Ni), and their ratios in extruded complete foods for adult dogs, their compatibility with nutritional guidelines, as well as food profile similarity. Basic composition was determined according to Association of Official Analytical Chemists (AOAC). Analyses for elements were performed using an atomic absorption spectrometer. All the evaluated dry dog foods met the minimum recommended levels for protein and fat. Eighteen tested dog foods (60%) did not meet at least one recommendation of nutritional guidelines. Four dog foods exceeded the legal limit of Fe and five foods exceeded the legal limit of Zn; in one of them, Zn level was almost twice higher. Dog foods with insect protein exceeded the legal limit for Mn content. Eight dog foods had an inappropriate Ca:P ratio. Heavy metals were below detection limit in all analyzed dog foods. The results seem to show the need for regular feed analyses of the elemental composition in raw materials before introducing supplementation and for the monitoring of the mineral composition of finished pet food.

Homemade versus extruded and wet commercial diets for dogs: Cost comparison

The present study aimed to verify and compare the costs of homemade diets with extruded and wet commercial diets for dogs in maintenance and consuming therapeutic diets (obesity, congestive heart failure, diabetes, hepatic encephalopathy, chronic kidney disease, and food hypersensitivity), which is important information that impacts in the choice of food by the owners. The maintenance energy requirements (MER) were estimated for adult dogs of different sizes (3 kg, 15 kg, 30 kg, and 50 kg) and the daily amounts of food intake were estimated for each type of food. The costs were calculated per day, per 1000 kcal of metabolizable energy of product and per kg of metabolic weight of the animal. Fourteen complete and balanced homemade diets were formulated, and in each proposed group, two diets with different protein sources were used. Under the conditions of the present study, it was possible to conclude that homemade diets were more expensive than dry maintenance diets and dry therapeutic diets, while commercial wet diets were more expensive in all of the scenarios.