Toxic element levels in ingredients and commercial pet foods

Serum aluminum in 176 feline patients with application to the diagnostic approach to a tremoring patient with kidney disease receiving aluminum hydroxide therapy

BACKGROUND

Control of circulating phosphorus concentrations in patients with chronic kidney disease is a mainstay of treatment and may include use of aluminum hydroxide as an intestinal phosphate binder. Serious complications of excess aluminum reported in dogs and man include encephalopathy, microcytic anemia, osteomalacia, and regional myopathy at serum concentrations exceeding 100 ng/mL. Reports of aluminum toxicosis are not available for cats receiving aluminum hydroxide and circulating aluminum concentrations are poorly characterized. The aim of this study is to establish therapeutic and toxic serum aluminum concentrations in cats and apply this data to an intoxication case.

RESULTS

Of cats with CKD who received aluminum hydroxide, 9/21 serum samples exceeded aluminum concentrations of 100 ng/mL. After removal of outliers, 18 cats with kidney disease who received aluminum hydroxide had mean serum aluminum concentrations of 69 ng/mL [95% CI: 42-97 ng/mL], which was significantly higher than mean aluminum concentrations in cats not receiving aluminum hydroxide (p = 0.0034). The mean aluminum concentration of 141 feline serum samples not receiving aluminum hydroxide was 29 ng/mL [95% CI: 24-33 ng/mL]. Of the 141 samples, 16 cats presenting for wellness or dental procedures had mean concentrations of 36 ng/mL [95% CI: 15-56 ng/mL]. This data was applied to a case of a 16-year-old spayed female domestic shorthair with IRIS stage 2 chronic kidney disease with a 7-month history of mild hindlimb weakness and intermittent right forelimb myoclonus. The patient received oral aluminum hydroxide, and the serum contained 376 ng/mL of aluminum suggestive of toxicosis. Resolution of clinical signs was noted following a switch to an aluminum-free phosphate binding medication, and, at 5-month follow-up, the serum aluminum concentration was 71 ng/mL.

CONCLUSIONS

Our data suggest that serum aluminum concentrations in cats exceeding 86 ng/mL can result in clinical aluminum toxicosis and is comparable to the 100 ng/mL toxic threshold described in humans. The data provided facilitate the diagnostic assessment of cats receiving aluminum hydroxide supplementation. Veterinarians must recognize the toxic effects of aluminum and pursue diagnostic testing in suspect cases to mitigate invasive and costly workup for aluminum-associated clinical signs or euthanasia due to deterioration of these patients.

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.

Quantitative analysis and health risk assessment of selected heavy metals in pet food samples using ultrasound assisted hydrogen peroxide extraction followed by ICP-OES analysis

There is a lack of information regarding the presence of heavy metals in feed ingredients for animals. Therefore, this study examines 10 feed samples collected from commercial pet food in South African market. The optimal working parameters for ultrasound assisted hydrogen peroxide extraction (UA-HPE) confirmed by multivariate optimization were sonication temperature at 80 °C for 60 min, sample mass of 0.1 g, and H2O2 concentration of 5 mol/L. The UA-HPE results demonstrated high accuracy of (>95%), reproducibility (≤1.9%), low method of detection limits (0.3498 and 0.49 μg/g), and strong linearity as confirmed by regression analysis. The environmental friendliness of the UA-HPE method was assessed using AGREEPrep metric tool that resulted with a score of 0.74. The concentration levels of Cd, Pb and As, ranged between 0.86 and 11.34, 4.50-11.45, and 2.61-12.5 μg/g, respectively greater than the standardized limits, whilst Cr, and Sn were below the limits of detection in all pet food. The health index calculations (HI > 1) revealed that the cat, dog, and horse feed pose health risk for animal consumption. Consequently, this study demonstrated a green, efficient, and cost-effective method for the analysis of animal feed with high accuracy.

A Review of Pet Food Recalls from 2003 Through 2022

This is a review of U.S. Food and Drug Administration (FDA) recalls of products that are for dogs and cats which took place from 2003 through 2022. It includes recalls for pet foods (food, treats, and chews), ingredients, supplements (vitamins and minerals), and drugs. There were 3,691 recalls during this period: 51% were Class I, 35% were Class II, and 14% were Class III. Food items and ingredients accounted for the majority or 68%, drugs for 27%, and supplements (vitamins and minerals) accounted for 5% of these recalls. Recalls that could be associated with dogs only accounted for 42%, with cats only 18%, and with multiple species 40%. The primary reasons for the recalls were biological contamination at 35%, chemical contamination at 32%, and cGMP violations at 8%. Almost 25% of the total recalls in the past 20 years were due to a melamine incident in 2007/2008 (73% of those were Class I). Salmonella recalls for the 20 years accounted for 23% of the total recalls (94 % of those were Class I). Although the recalls for vitamins and minerals accounted for only 5.6% percent of the total, 70% of those were Class I and 30% Class II. Pet food is a complex part of the processed food industry, and the processing of pet food is subject to at least 40 different federal regulations. To avoid recalls and be successful, pet food manufacturers need a robust food safety culture to meet all of these requirements to produce a safe product. In contrast, the melamine contamination (an adulteration event) in 2007/2008 which resulted in animal deaths and recalls is a prime example of the need for an effective and robust supplier approval program in order to avoid fraudulent suppliers in the future.

Lead concentrations in commercial dogfood containing pheasant in the UK

UK and EU regulators are evaluating the potential health benefits of restricting the use of lead ammunition. Little information is available on exposure of pets to ammunition-derived dietary lead from petfood containing meat from wild-shot game animals. We found dogfood including wild-shot pheasant meat to be widely available in the UK. 77% of samples from three raw pheasant dogfood products exceeded the EU maximum residue level (MRL) for lead in animal feed, with mean concentrations approximately 245, 135 and 49 times above the MRL. Concentrations > MRL were also found in a dried food containing pheasant, but not in a processed food, nor in chicken-based products. Lead concentrations in raw pheasant dogfood considerably exceeded those in pheasant meat sold for human consumption, possibly because the dogfood mincing process further fragmented lead particles from shot. Dogs frequently consuming such high-lead food risk adverse health effects; this should be considered within decision-making processes about regulation.

Microspatial distribution of trace elements in feline dental hard tissues: early life exposure to essential and toxic elements

Introduction

Trace elements play a key role in dental tissue development, as dental hard tissues accumulate both essential and toxic trace elements during mineralization. Characterization of the spatial accumulation pattern of trace elements may provide insight into exposure to toxic elements over time and to the nature of disease processes affecting the hard dental tissues. Here, we present the first report of the use of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to map the microspatial distribution of multiple trace elements, essential and toxic, across feline dental hard tissues.

Methods

Eleven teeth were extracted from 8 cats. Nine teeth were from 7 cats diagnosed with idiopathic tooth resorption on intraoral radiographs prior to extraction. Two teeth were included from a cadaver that had no signs of tooth resorption on intraoral radiographs. The normal dental tissue was analyzed from each sample using LA-ICP-MS to map the microspatial distribution of essential and toxic trace elements across feline enamel, dentin, and cementum.

Results

Results showed a higher accumulation of barium and strontium in coronal dentin as compared to root dentin. The timing of the accumulation mirrors nursing timelines seen in teeth from human and non-human primates, consistent with barium and strontium being sourced from maternal milk. Results also showed a higher uptake of lead in the coronal dentin, suggesting this lead exposure was likely passed from mother to offspring.

Discussion

This work characterizes a baseline for elemental distribution in feline teeth linked to early life exposure to toxic elements such as lead and provides a framework for future studies investigating long-term environmental exposures to trace elements, essential and toxic, and their involvement in feline systemic and dental diseases.

Mineral and heavy metal content in dry dog foods with different main animal components

Dog caregivers, mainly for economic reasons and easy availability, choose dry, over the counter diets (OTC). The mineral composition of OTC foods depends primarily on the components used in the production of the pet food. Regardless of the main component of the food, it must meet the recommended minimum mineral content, established by nutritional guidelines. Therefore, the aim of this study was to determine the mineral (Ca, K, Mg, Na, Fe, Mn, Zn, Cu, Mo) and heavy metal content (Pb, Co, Cd, Cr, Ni) using the methods of colorimetry and mass spectrometry, of OTC dry dog foods and to compare with the FEDIAF and AAFCO nutritional guidelines. Dry foods pose no risk to dogs in terms of heavy metal content. The worst results in terms of mineral content were obtained in mixed foods, therefore it is worth considering feeding the dog a mono-protein food. The PCA analysis disproved our hypothesis and revealed that the main animal source did not statistically significantly affect the levels of minerals and their ratios. However, the analysis of contrasts confirms the differentiation of the content of individual minerals between the groups of foods. For the first time, we proved that pet food with a mineral composition similar to the MIN-RL may be characterized by unfavorable mineral ratios.

Nutritional Composition and Untargeted Metabolomics Reveal the Potential of Tetradesmus obliquus, Chlorella vulgaris and Nannochloropsis oceanica as Valuable Nutrient Sources for Dogs

The growing pet population is questioning the sustainability of the pet food system. Although microalgae may constitute a more sustainable food resource, the assessment of their potential for canine diets is almost non-existent. The present study aimed to evaluate the potential of three microalgae species (Tetradesmus obliquus, Chlorella vulgaris and Nannochloropsis oceanica) grown locally in industrial photobioreactors as alternative food resources for dogs. A detailed characterization of their nutritional composition and metabolomic profile was carried out and related to the nutritional requirements of dogs. Overall, the essential amino acid content exceeded the amounts required for dogs at all life stages, except methionine and cysteine. The three microalgae were deficient in linoleic acid, N. oceanica presented a linolenic acid content below requirements and T. obliquus and C. vulgaris were deficient in arachidonic and eicosapentaenoic acids. The fiber was mainly composed of insoluble dietary fiber. The mineral profile varied greatly with the microalgae species, demonstrating their different potential for dog feeding. Untargeted metabolomics highlighted glycolipids, glycerolipids and phospholipids as the most discriminating compounds between microalgae species. Overall, the results support the potential of T. obliquus, C. vulgaris and N. oceanica as valuable macro- and micro-nutrients sources for dog feeding.

Occurrence of Toxic Metals and Metalloids in Muscle and Liver of Italian Heavy Pigs and Potential Health Risk Associated with Dietary Exposure

Muscle and liver tissues from Italian heavy pigs were analyzed to investigate whether the chronic consumption of these products by local consumers could represent a health risk in relation to the contamination by some toxic metals and metalloids (TMMs). The concentrations of Al, As, Cd, Cr, Cu, Fe, Ni, Pb, Sn, U, and Zn were measured with an inductively coupled plasma-mass spectrometer, while Hg analysis was performed by using a mercury analyzer. Fe, Zn, and Cu were the most abundant elements in both tissues, while U was detected only at ultra-trace levels. As, Cd, Cu, Fe, Hg, Pb, U, and Zn showed significantly higher concentrations in livers compared to muscles (p ≤ 0.01), with Cd and Cu being 60- and 9-fold more concentrated in the hepatic tissue. Despite this, concentrations of all TMMs were found to be very low in all the samples to the point that the resulting estimated dietary intakes did not suggest any food safety concern. Indeed, intakes were all below the toxicological health-based guidance values or resulted in low margins of exposure. Nevertheless, in the calculation of the worst-case exposure scenario, the children's estimated intake of Cd, Fe, and Zn through the sole consumption of pig liver contributed to more than 23, 38, and 39% of the tolerable weekly intakes of these elements, while the combined consumption of pig liver and pig muscle to more than 24, 46, and 76%. These findings alert about the probability of exceeding the toxicological guidance values of Cd, Fe, and Zn though the whole diet, suggesting long-term negative health effects for the younger population.