The Values of Potentially Toxic Elements (PTEs) in Prescription

Overview

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Key numbers

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Biological Trace Element Research (2025) 204:277–287
commercial diets for cats and dogs. A total of 84 dry cat diets and 152 dry dog diets were analyzed. Prescription cat diets
were subgrouped into digestive (n = 24) and urinary (n = 20), while prescription dog diets were categorized as digestive
(n = 28), urinary (n = 16), hypoallergenic (n = 20), and joint (n = 12). Additionally, non-prescription diets from various
brands and flavors were included for dogs (n = 76) and cats (n = 40). Chromium (Cr), arsenic (As), boron (B), aluminum
(ICP OES) (Thermo iCAP 6000 series) at appropriate wavelengths. No significant differences were found in mean As, B,
and Co levels between total dog and cat diets (p > 0.05). However, mean Cr and Al levels were significantly higher in dog
diets compared to cat diets (p < 0.001). Among cat diets, no significant differences were observed for Cr, As, B, Al, or Co
(p > 0.05). In non-prescription dog diets, mean Cr was significantly higher than in urinary group (p < 0.001). Mean Al levels
in digestive, joint, and non-prescription groups were higher than in urinary group (p < 0.001). The levels of Cr, As, B, Al,
In recent years, the pet diet industry has been growing and balanced diets (3). A wide range of commercial diets
dog nutrition (1, 2). These products are specifically formu- scription and non-prescription. The elemental composition
lated for ease of use and convenience. It has been proposed of these diets varies significantly (4, 5). European legislation
University, Goztepe, Istanbul 34734, Türkiye
serious health problems in companion animals (7). Among
of Tirana, Kodër Kamëz, 1029 Tirana, Albania
278 B. Bilgiç et al.
both humans and animals (8–10). Arsenic (As), as a metal-
tion states (11). In both animals and humans, natural boron
(B) predominantly exists as boric acid which interacts with A total of 84 dry cat diets and 152 dry dog diets collected
through electron donor–acceptor interactions at intracel- tive (n = 24) and urinary (n = 20)) and non-prescription (n =
lular pH (12). Although boron plays an essential role on 40); commercial dry dog diets were subgrouped as prescrip-
growth performance, bone and embryonic development, tion (digestive (n = 28), urinary (n = 16), hypoallergenic
liver functions, redox balance, inflammatory processes, (n = 20) and joint (n = 12)) and non-prescription (n = 76).
and brain activity, high doses were reported as lethal (13). Non-prescription dry cat diets of various brands and flavors,
animals (14). Cobalt (Co) has been known as an essential clinics, were collected for analysis. All pet diet samples were
micronutrient in the form of vitamin B12 (hydroxocobala- obtained as unopened packages directly from the compa-
immune system (15). flavors, and ingredients manufactured in Italy, France, and
chromium (Cr) (exceeding the upper limit by 22.22% in cat diets formulated for nutritional support in cases of atopic/
foods and 31.25% in dog foods) as defined by the Hygieni- allergic dermatitis, diet-related adverse skin reactions, and
cal Standard for Pet Feed of China (Announcement No. 20, nutritional intolerances were included in the hypoallergenic
1. were surpassed, while concentrations of other toxic group. The diets formulated for joint, bone, cartilage, and
metals (Cd, Hg, As) remained within acceptable limits (16). mobility support were included in the joint group. Similarly,
Al, 31.9%; mercury, 100%; lead, 80.55%; uranium, 95.83%; lyzed pork, poultry, fish, and various vegetable proteins.
and vanadium, 75%. In cat foods, the corresponding val-
ues were as follows: Al, 10.71%; Hg, 100%; Pb, 32.14%; Determination of Element Concentrations
U, 85.71%; and V, 28.57% (17). In contrast, a study con-
ments (PTEs) highlight the significance of not only environ- selected wavelengths were 267.716 nm for Cr, 189.042
mental exposure but also dietary intake levels. This study nm for As, 249.773 nm for B, 167.079 nm for Al, and
aimed to determine the levels of Cr, As, B, Al, and Co in 228.616 nm for Co. To ensure a representative sampling,
The Values of Potentially Toxic Elements (PTEs) in Prescription and Non‑prescription Dry Cat… 279
calculated. The digestion process was performed by add- Cr levels (mean ± SD) were 2.932 ± 2.665 µg/g and 4.422

Methods (brief)

(ICP OES) (Thermo iCAP 6000 series) at appropriate wavelengths. No significant differences were found in mean As, B,
and urinary systems in various chemical forms and oxida- Diet Samples
(B) predominantly exists as boric acid which interacts with A total of 84 dry cat diets and 152 dry dog diets collected
animals (14). Cobalt (Co) has been known as an essential clinics, were collected for analysis. All pet diet samples were
while prolonged exposure, even at low levels, can lead stored under appropriate conditions. Expired samples were
been published in the literature regarding the determination of gastrointestinal diseases, maldigestion, absorptive disor-
samples exceeding the maximum tolerable limits (MTL) set companies with various flavors and ingredients, manufac-
and AAFCO nutritional guidelines, the heavy metal content in all diet samples using an inductively coupled plasma-
(Pb, Co, Cd, Cr, Ni) in dry dog foods did not pose any risk optical emission spectrometer (ICP OES; Thermo iCAP
various prescription and non-prescription dry pet diets for multiple batches of each type of pet diet were collected.
From these batches, three subsamples were prepared for Results
calculated. The digestion process was performed by add- Cr levels (mean ± SD) were 2.932 ± 2.665 µg/g and 4.422
Merck) to the diet samples, followed by thermal decom- µg/g and 2.785 ± 2.165 µg/g; B levels (mean ± SD) were
0.2 g of dried sample was used for each digestion. After differences were observed between the groups in terms of
cooling to room temperature, the samples were vortexed mean As, B, and Co levels (p > 0.05). However, the mean
enization was applied before acid addition, the samples those in cat diets (p < 0.001) (Table 1, Fig. 1).
became homogenous during digestion due to complete Among the prescription cat diets Cr, As, B, Al, and
breakdown of the organic matrix. Following digestion, Co levels (mean ± SD) were measured as 3.277 ± 2.850

Implications

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
3171d06	2026-08-02	major	1 section added
bc84bfc	2026-08-02	major	6 sections added; narrative text revised