Rice is one of the most commonly used ingredients in commercial kibble. Rice plants take up inorganic arsenic relatively easily from the soil and irrigation water. A small pilot study from the University of Helsinki investigated for the first time whether this is measurable in the hair of dogs on a rice-based diet.
Wolfork contains no rice or grains
Exclusively unprocessed animal ingredients
What is inorganic arsenic and where does it come from?
Arsenic is a metalloid that occurs naturally in soil and water. There are two main forms: organic arsenic, present in fish and seafood and considered non-toxic, and inorganic arsenic, the toxic form. Rice plants take up inorganic arsenic relatively easily from the soil and irrigation water, making rice and rice products a known source of inorganic arsenic in the diet.
In humans, recommendations already exist to limit rice consumption, particularly for young children. Inorganic arsenic has been classified by EFSA as a non-threshold carcinogen, meaning that in principle any exposure is relevant. However, disease or cancer outcomes were not investigated in this study.
For dogs, little research is yet available on chronic exposure to inorganic arsenic through food. Dogs typically eat the same food, every day, for years. This makes the question of long-term exposure through fixed ingredients more relevant than for humans, who eat much more varied diets.
The study: pilot study with sixteen dogs
Rosendahl et al. (2019) compared the inorganic arsenic content in the hair of seven Staffordshire Bull Terriers fed a strongly rice-based kibble diet (rice as the first or second ingredient, at least 80 percent of the diet, for at least one year) with nine dogs that had no rice at all in their diet. The study was part of a larger diet study in Finland.
Hair analysis is a recognised method for measuring long-term exposure to inorganic arsenic. Hair reflects exposure over a longer period, but does not provide direct information about health damage. Organic arsenic from fish does not accumulate in hair and was not a confounding factor in the measurement.
The study included only Staffordshire Bull Terriers with a strongly rice-based diet. The findings cannot be generalised to all kibble, but apply specifically to the rice-rich diet profile studied.
Rosendahl et al., 2019 |
Veterinary Record, DOI: 10.1136/vr.105493 — Pilot study, n=16 Staffordshire Bull Terriers, University of Helsinki. Hair analysis for inorganic arsenic in a strongly rice-based diet versus no rice. |
What the measurement showed
The inorganic arsenic content in hair was significantly higher in dogs on a rice-based diet than in dogs without rice (p = 0.005). Age and sex had no significant influence.
The average level in the rice-diet group was slightly above the level reported by Neiger and Osweiler as a typical background value for non-exposed dogs. No clinical signs of arsenic poisoning were observed in the dogs in this study. The authors state that the toxicological significance of the difference is currently unclear, but consider it a consideration that warrants further research.
Scientifically honest
This is a pilot study with only sixteen Staffordshire Bull Terriers and hair measurements only. The measured values were well below toxicity thresholds and no clinical symptoms of arsenic poisoning were found. Hair analysis reflects long-term exposure but does not provide direct information about health damage. Parallel urine testing and a larger sample are needed for a more reliable risk assessment. The findings apply specifically to very rice-heavy diets and do not apply to all kibble.
What this means as a consideration
The authors state that a diet high in rice may, over the long term, contribute to higher exposure to inorganic arsenic in dogs. This is a cautious conclusion, not an established health risk. They advise variation in dogs' diets to limit the accumulation of specific contaminants.
Wolfork contains no rice. That is the factual statement that is relevant based on this research. No statements can be made, based on this study, about the health effects of the difference in exposure found in this research.
What this means in practice
Dogs on a strongly rice-based kibble diet had significantly higher inorganic arsenic levels in their hair than dogs without rice in this pilot study. No clinical signs of poisoning were observed and the values found were below toxicity thresholds. The study investigated exposure, not disease outcomes. The findings apply specifically to the studied, strongly rice-rich diet and are a consideration that warrants further research.
Wolfork: no rice, no grains, no starch
Exclusively unprocessed animal ingredients
Source
Rosendahl, S., Anturaniemi, J. & Hielm-Björkman, A. (2019). Hair arsenic level in rice-based diet-fed Staffordshire bull terriers. Veterinary Record. DOI: 10.1136/vr.105493
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