Mineral and heavy metal content in dry dog foods

Overview

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Key numbers

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License:   This work is licensed under a Creative Commons Attribution 4.0 International License.
Version of Record: A version of this preprint was published at Scienti c Reports on April 13th, 2023. See
1 Department of Monogastric Animal Sciences, Division of Animal Nutrition and Food, West Pomeranian University
of Technology in Szczecin, Klemensa Janickiego 29, 71-270 Szczecin, Poland
2 Department of Agroecology and Crop Production, University of Agriculture in Krakow, Mickiewicza 21, 31-120
3 Department of Agroengineering, West Pomeranian University of Technology in Szczecin, Juliusza Słowackiego 17,
The number of dogs in households is increasing year by year1 . Dog caregivers, mainly for economic reasons and due to the
and their excess or deficiency can impair animals’ health2, 3 . Regardless of the main component of the food, it must meet
which depends mainly on the component, its source, but also on the production process of the pet food4 . Thus, the mineral
content of dog food needs to be frequently monitored5 . Long-term use of the same diet results in correlations between the
blood Pb levels, and blood Pb levels decline as the dog ages6 . According to the literature data, fish are particularly exposed to
the presence of heavy metals7 . What is important, fish and fish wastes are used to produce pet food8 . Pet foods containing
but free-range meat can be also contaminated with heavy metals. Beef is a valuable source of iron, and lamb – of copper9 .
excess of a given mineral. There are nutritional guidelines in the world that are recommended in Europe10 and those that are
recommended in the America11 . Although they refer to the same product as pet food, they differ in the acceptable minimum
components and to compare mineral adequacy with the FEDIAF10 and AAFCO11 nutritional guidelines for healthy adult dogs.
For this purpose, an analysis of 15 minerals was undertaken, including macrominerals, trace elements and heavy metals.
Macrominerals Among the analyzed dog foods there were 13 foods with fish (F) as the main animal component, 6 with poultry
(P), 6 with lamb (L), 6 with beef (B), 6 with at least two animal components (MIX) and a group of 4 other foods (O), one
(MAX-LL) for trace elements. For calcium (Ca), both FEDIAF and AAFCO give a recommended MIN-RL - 0.5 and MAX-RL
– 2.5 g / 100 g DM of dog food. Our research shows that the calcium level in 68 percent (F2, F3, F4, F7, F8, F9, F10, F11, F12,
F13, P1, P2, P3, P4, P6, L1, B1, B2, B3, B4, B5, B6, M1, M2, M4, M5, O1, O2, O3) of foods was below the MIN-RL (Table 1)
The highest statistically significant average level of calcium was obtained for the group of foods with lamb (0.62 g / 100 g DM)
(Table 2). It was the only food group where nearly all of the foods (except L1) met the MIN-RL of calcium. The groups of
(P) and other foods (O). Disturbingly low calcium content was found in M4 food (0.06 g / 100 g DM) and the highest – in
AAFCO give the same MIN-RL and MAX-RL (0.4 and 1.6 g / 100 g DM, respectively). Statistically significantly the highest
mean content of phosphorus was obtained in the F8 food (1.95 g / 100 g DM), and its lowest level was found in the B1 food
(0.66 g / 100 g DM). Statistically significantly the highest mean content of phosphorus was obtained in the group of foods
with lamb (1.36 g / 100 g DM), while the lowest – in the group of foods with beef (1.07 g / 100 g DM). All groups differed
analyzed foods had phosphorus content below the MIN-RL, while 6 dog foods exceeded the MAX-RL (F8, F9, F13, L2, M6,
O1), respectively by 21.25, 7.5, 0.63, 0.63, 5.00 and 9.38 percent. The minimum recommended level for potassium established
one pet food (L1) did not meet the MIN-RL, while for AAFCO it would be 7 percent of analyzed pet foods (P6, L1, M3). In
the case of potassium (K), the highest level was statistically significantly highest in the group of other foods (0.97 g / 100 g
DM), while the lowest – in the group of foods with lamb (0.74 g / 100 g DM). All groups differed statistically significantly in
analyzed met the recommended minimum levels by both FEDIAF and AAFCO – 0.07 and 0.06 g / 100 g DM for magnesium,
and 0.1 and 0.8 g / 100 g DM for sodium. In the case of sodium, significant differences between the groups were found for all
Trace elements and heavy metals FEDIAF provides both the MIN-RL (3.60 g / 100 g DM) and the MAX-LL (68.18 mg /
100 g DM) of iron (Fe), while AAFCO only recommends the minimum level (4.0 mg / 100 g DM) (Table 3). All analyzed
found in the F6 food (33.86 mg / 100 g DM), while the lowest was determined also in food with fish (in the F8 food - 4.82 mg /
100 g DM). Statistically the highest amounts of iron were found in the group of mixed foods (23.67 mg / 100 g DM) (Table 4),
while the lowest – in the group of other foods (11.93 mg / 100 g DM). All groups of foods differed statistically significantly in
minimum recommended (8.0 mg / 100 g of DM). The lowest level of zinc was found in the O2 food (3.04 mg / 100 g DM). The

Methods (brief)

(Pb, Co, Cd, Cr, Ni) using the methods of colorimetry and mass spectrometry, of OTC dry dog foods and to compare with the
21°C) until analyzes. Bags were opened on the same day. From each bag, a representative sample was collected for laboratory
analyzes48 . Samples of foods were ground in a laboratory mill type KNIFETEC 1095 (Foss Tecator, Höganäs, Sweden), placed
Chemical analyzes To determine the dry matter, the samples were dried at 105°C until constant weight according to
sample, determined spectrophotometrically, from P2O5 to total phosphorus, was calculated according to the chemical equivalent
1. Gerber, N. et al. Variability of selected trace elements of different meat cuts determined by icp-ms and drc-icpms. Animal
1. Gregório, B. J. et al. Flow-based dynamic approach to assess bioaccessible zinc in dry dog food samples. Molecules 25,
1. ISO. Iso method 6498:2012, animal feeding stuffs – guidelines for sample preparation. Int. Organ. for Standardization,

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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