Brewers Rice in dog and cat food

Is it OK for dogs and cats?

Dogs

Brewers rice is small pieces of milled rice, and the cited studies do not support the worry that it is an indigestible 'filler': in a feeding study, dogs digested a brewers rice diet better than corn, sorghum, pea or lentil diets, though it gave larger glucose and insulin responses in the first 30 minutes after meals than sorghum, pea or lentil diets. One small study found more arsenic in the hair of dogs fed rice-based diets; it measured exposure, not illness.

Cats

Adult cats that are not nursing kittens do not need carbohydrate in their diet, but cats digest properly cooked starch well: in a cat study, starch in a brewers rice kibble was 98.6% digested, more than in sorghum, lentil or pea diets. The authors suggested that starch affects blood glucose and insulin less in cats than in dogs.

How settled this is: A popular concern the sources do not support

What brewers rice is

Brewers rice is made up of broken fragments of milled rice kernels. US grain standards define milled rice as kernels with the hulls and at least the outer bran layers removed. They define broken kernels as pieces less than three-quarters of a whole kernel. 'Brewers milled rice' is the class that is mostly broken pieces, with no more than 25% whole kernels. Its pieces do not meet the size requirements for the 'second head' and 'screenings' classes. Like other classes of milled rice, it has its own quality grades. The EU feed catalogue calls similar material 'broken rice': pieces of rice kernel shorter than three-quarters of a whole kernel, which may have been parboiled.

Why it is in pet food

Brewers rice is used as a starch source, and starch supplies energy. Dogs and cats digest properly cooked starch from grains with more than 90% efficiency. Studies of extruded (kibble) diets compared brewers rice with cassava flour, corn, sorghum, peas and lentils as the main starch source. Brewers rice diets were among the most digestible for both dogs and cats.

What it does in the food

Brewers rice is mainly starch; the EU catalogue lists starch as the nutrient to declare for broken rice. Carbohydrate is not an essential nutrient for adult, non-breeding dogs and cats, because the body can make glucose from amino acids and fat. Dogs usually use glucose from dietary carbohydrate. Carbohydrate can become conditionally essential for dogs during growth, pregnancy and lactation, and for cats during lactation. Cats normally make glucose continuously from protein and fat, and are adapted to a moderate intake of complex carbohydrates. Milling removes the bran layers. Rice bran is a separate feed material, used as a fibre source.

Safety and limits

The cited sources set no limit specific to brewers rice. Dogs and cats digested brewers rice diets very well in feeding studies. Rice can contain inorganic arsenic. One small study in Staffordshire bull terriers with atopic dermatitis compared seven dogs eating dry foods with rice as the first or second ingredient with nine dogs that ate no rice, most of them raw-fed. The rice-fed dogs had higher inorganic arsenic levels in their hair. The study measured exposure, not illness, and did not look at brewers rice specifically. The authors suggested that long-term rice-based feeding is a possible source of chronic arsenic exposure in dogs.

What depends on the amount and the recipe

Processing matters: starch must be properly cooked, as in kibble extrusion, to be well digested. So does the rest of the recipe. Brewers rice is mainly starch, so in a complete food the protein, fat, vitamins and minerals come from other ingredients. Merck notes that diets built from only a few foods are often inadequate; for example, an exclusive hamburger-and-rice diet can cause calcium deficiency in dogs and cats. Blood-glucose response differs between starch sources. Researchers studying dogs suggest starch choice could help shape that response, but say more studies are needed. Based on one small study, eating a rice-based diet for long periods may matter for arsenic exposure.

Not the same as

• Brown rice — Rice with only the hull removed, so it keeps its bran layers; brewers rice is milled, with the bran removed.
• Rice bran — The outer layers of the rice kernel plus part of the germ, removed during milling; used as a fibre source.
• Rice protein — A protein fraction made during rice starch production by wet milling and separation; not the starchy kernel pieces.
• Brewers dried yeast — Despite the similar name, this is dried yeast (such as Saccharomyces), not rice.
• Brewers grains — Leftovers from brewing, made of malted and unmalted cereals; not milled rice pieces.

Sources

1. 7 CFR Part 868, Subpart E: United States Standards for Milled Rice (sections 868.301, 868.302, 868.313; eCFR text as of 1 Oct 2026) — U.S. Electronic Code of Federal Regulations (eCFR), 2026. Defines milled rice (hulls and at least outer bran layers removed), broken kernels (less than three-fourths of a whole kernel), brown rice (hulls removed), the 'brewers milled rice' class (no more than 25% whole kernels and not meeting the second-head or screenings kernel-size requirements) and its grade requirements.
2. Commission Regulation (EU) 2022/1104 amending Regulation (EU) No 68/2013 on the Catalogue of feed materials — Official Journal of the European Union (Publications Office of the EU), 2022. Entries 1.6.1 broken rice (kernel pieces shorter than three-quarters of a whole kernel, may be parboiled; starch to be declared), 1.6.6 husked rice, 1.6.10 rice bran, 1.6.20 rice protein, 1.12.12 brewers' grains, 12.1.5 inactivated yeasts [brewers' yeast].
3. Carciofi AC et al. Effects of six carbohydrate sources on dog diet digestibility and post-prandial glucose and insulin response. J Anim Physiol Anim Nutr 2008;92:326-336 (PubMed record) — Journal of Animal Physiology and Animal Nutrition (Wiley); abstract via PubMed/NCBI, 2008. In 36 dogs fed extruded diets, brewer's rice and cassava diets had the greatest digestibility, ahead of corn and sorghum, with peas and lentils lowest; starch digestibility was over 98% in all diets; brewer's rice, corn and cassava gave greater immediate (first 30 min) post-meal glucose and insulin responses, sorghum, lentil and pea greater later responses; more studies are needed on modulating glycaemic response.
4. de-Oliveira LD et al. Effects of six carbohydrate sources on diet digestibility and postprandial glucose and insulin responses in cats. J Anim Sci 2008;86:2237-2246 (PubMed record) — Journal of Animal Science; abstract via PubMed/NCBI, 2008. In 36 cats, the brewers rice diet had greater DM, OM and energy digestibility than sorghum, corn, lentil and pea diets, and 98.6% starch digestibility (greater than sorghum, lentil and pea); cats digest starch efficiently when properly processed into kibble; the data suggest starch affects postprandial glucose and insulin less in cats than in dogs and humans.
5. Nutritional Requirements of Small Animals (Merck Veterinary Manual; full review Nov 2023) — Merck Veterinary Manual (Merck & Co., Inc.), 2023. Carbohydrates are not essential for adult non-reproducing dogs and cats; conditionally essential in growth, gestation and lactation (dogs) and lactation (cats); cats are in continuous gluconeogenesis and adapted to moderate complex carbohydrate; cooked starch digested with >90% efficiency; rice bran as a fibre source; diets from a limited number of foods are often inadequate, e.g. an exclusive hamburger-and-rice diet can induce calcium deficiency.
6. Rosendahl S et al. Hair arsenic level in rice-based diet-fed Staffordshire bull terriers. Vet Rec 2020;186:e15 — Veterinary Record (BVA/BMJ), via PubMed Central, 2020. Atopic Staffordshire bull terriers: hair inorganic arsenic was higher in seven dogs eating 80% or more of a dry food with rice as first or second ingredient than in nine dogs eating no rice (mostly raw-fed); the authors suggest long-term rice-based feeding is a risk for chronic inorganic arsenic exposure.

Checked against these sources on 2026-10-15. Definitions are in our own words. This is a reading aid, not veterinary advice: a vet who knows your animal comes first.