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Ingredient file // Vitamin or mineral

Magnesium Oxide

A practical magnesium source, without special benefits

Magnesium oxide is a concentrated mineral powder added to balance a dog's diet. It contributes magnesium, but its place on a label cannot tell you the finished food's magnesium level or whether it will calm an anxious dog.

Role in the food Supporting nutrient
What it is
A concentrated magnesium mineral made by heating magnesium carbonate and blended into animal food.
Made from
Mined magnesium carbonate ore
Main job
Balances dietary magnesium
Typical amount
Typical amount unpublished; one dog study used 0.1%
Watch for
Dogs on a prescribed struvite diet
Not the same as
Magnesium sulfate

Straight answer

Is Magnesium Oxide safe for dogs?

Judge the finished food, not this powder

Magnesium oxide near the other minerals usually signals recipe balancing. Its list position cannot tell you the finished food's magnesium level. Check the nutritional adequacy statement for your dog's life stage. If your dog has a diagnosed urinary condition, follow the prescribed diet and ask about its total magnesium.

Why it is in the food
Balances dietary magnesium

Our read // In our catalog

In 1 of every 16 foods we track

Share of foods that list it

6%

195 of the 3,204 foods with an ingredient list on file, from 9 brands. 141 dry dog food, 47 wet dog food, 5 freeze-dried dog food.

Each square is 1% of the catalog

Where it sits on the label

Median position 25. In the top five of 0 foods, so it is usually a minor ingredient.

Top five List position, heaviest first

Above the salt

2%

Usually listed after the salt, which caps it at roughly 1% of the recipe in 98% of foods.

Price per lb

Foods with it $3.67
All foods $3.25

Median of the cheapest bag price across 125 priced foods, 13% above the catalog. The price is the food's, not the ingredient's.

Who leans on it

49%

of the foods that list it are from Royal Canin. 9 brands use it in total.

What it is

How it is made

Mineral processors mine magnesite for industrial and feed uses. They crush and wash the ore, then heat it so carbon dioxide leaves the magnesium carbonate and magnesium oxide remains.6,7

  1. 01 // Source Magnesite ore Mined magnesite supplies the magnesium carbonate used to make magnesium oxide.
  2. 02 // Process Crushed and washed The ore is crushed, separated and washed before kiln firing.
  3. 03 // Process Heated in kiln Heat breaks down magnesium carbonate, releasing carbon dioxide and leaving magnesium oxide.
  4. 04 // Output Graded mineral The material is graded and packed for blending with other feed ingredients.

What is in it

Composition, dry matter

51

% magnesium

About half this mineral powder is elemental magnesium, so a small recipe addition can change the finished food's magnesium total.

Magnesium 482-543 g/kg4
Ash 96.9-100%4
Crude protein 0%4
Crude fat 0%4

The dry-matter magnesium range covers only 3 reported samples. The zero protein and fat entries each rely on 1 observation, and mineral content varies between suppliers.4,6,7

Why it is in the bag

A small dose of a required mineral

  1. Main nutrition
  2. Supporting nutrient
  3. Does a job
  4. Mostly filler

Magnesium is a required nutrient, and AAFCO sets a minimum for dog food. This powder is about half magnesium, so a little does real work: one dog study added it at 0.1% of the diet, roughly 0.5 g of magnesium per kg of food. It sits low on labels because so little is needed, not because it pads the bag. Other ingredients also carry magnesium, so its share likely varies by recipe.1,4,5,11

  1. 01

    Meets a mineral target

    AAFCO sets a magnesium minimum for dog food. Formulators count the magnesium already present in other ingredients and add a mineral source if the recipe needs more.5

  2. 02

    Fits mineral premixes

    Its high magnesium concentration adds little bulk to a recipe. Feed-grade suppliers sell magnesium oxide for blending with other minerals before those ingredients enter a food.4,7

  3. 03

    Keeps mineral cost down

    Alabama Cooperative Extension describes magnesium oxide as an inexpensive magnesium source for cattle feed. That supports the cost rationale, though it does not publish dog-food prices.8

How much In 5 experimental dog diets, researchers added 1 g of magnesium oxide per kg of food, or 0.1% as fed.1

Our read // The claims

What the evidence supports

Strong: controlled studies in dogs agree. Some: small or mixed dog data. Thin: mechanism or lab work only. None: nothing, or the evidence points the other way.

  1. Brands say

    Magnesium oxide supplies magnesium dogs need

    Evidence

    1. Strong
    2. Some
    3. Thin
    4. None

    The feed table averages 514 g of magnesium per kg of dry ingredient, and AAFCO specifies a dietary magnesium minimum. A dog study included oxide at 1 g/kg of food. Adequacy still depends on the whole recipe.1,4,5

  2. Critics say

    Oxide is less absorbable than magnesium citrate

    Evidence

    1. Strong
    2. Some
    3. Thin
    4. None

    In a randomized crossover trial of 20 men, citrate produced greater urinary magnesium excretion than oxide after a single dose. A citrate maker funded the trial. It did not test dogs eating finished food.3

  3. Brands say

    Magnesium oxide calms anxious dogs

    Outruns the evidence

    Evidence

    1. Strong
    2. Some
    3. Thin
    4. None

    A marketed calming tablet combines oxide with magnesium hydroxide, chamomile and amino acids. Its product page provides no controlled dog trial isolating oxide. The available human crossover trial measured absorption, not behavior.3,10

  4. Owners say

    Magnesium oxide causes bladder stones

    Outruns the evidence

    Evidence

    1. Strong
    2. Some
    3. Thin
    4. None

    The ACVIM expert consensus identifies infection-induced struvite as the common canine form and prioritizes treating urinary infection. It reserves low-magnesium therapeutic foods for specific cases. An oxide listing alone does not show stone risk.2

Straight answers

What owners ask

  1. Q01

    Is it just filler?

    No

    It supplies magnesium, a required nutrient, without useful protein or fat. Its place near the end of an ingredient list is consistent with the small amount needed to adjust a mineral recipe.4,5,11

  2. Q02

    Does it cause bladder stones?

    Not by itself

    Most canine struvite stones involve urinary infection. Therapeutic diets address total minerals and urine acidity alongside infection treatment. An ordinary ingredient list cannot tell you the food's total magnesium or your dog's stone risk.2,11

  3. Q03

    Is the oxide form useless?

    No

    The human comparison found less magnesium uptake from oxide than citrate, not zero uptake. It did not measure dogs eating kibble, so it cannot quantify how much magnesium a dog absorbs from this ingredient.3

  4. Q04

    Should I add more magnesium?

    Usually no

    Check that your dog's food has a nutritional adequacy statement for its life stage. Extra magnesium changes the mineral intake, and large supplement ingestions can cause illness. Ask about the finished food's total magnesium for a specific medical need.9,11

Who uses it

Brands, best sellers and the company it keeps

Top brands, by foods that list it

  1. Royal Canin 96 / 160
  2. Horizon 26 / 27
  3. Hill's 20 / 116
  4. Eukanuba 20 / 35
  5. NutriSource 20 / 91
  6. K9 Natural 5 / 8
  7. Artemis 3 / 11
  8. Bil-Jac 3 / 32
  9. Pedigree 2 / 42

Foods that list it / all the brand's recipes we track.

Amazon best sellers that list it

  1. #29 Royal Canin Small Adult Dry Dog Food
  2. #80 Royal Canin Yorkshire Terrier Adult Dry Dog Food
  3. #100 Royal Canin French Bulldog Adult Dry Dog Food

Rank on Amazon's dog food best seller list, checked October 2026.

Usually listed with, share of the foods that list it

  1. Chicken Fat 59%
  2. Natural Flavor 49%
  3. Brewers Rice 48%
  4. Dried Plain Beet Pulp 47%
  5. Chicken By-Product Meal 39%
  6. Wheat Gluten 37%
  7. Chicken 37%
  8. Corn 36%
  9. Fish Oil 31%
  10. Powdered Cellulose 22%
  11. Vegetable Oil 21%
  12. Carrots 20%

On the shelf

Foods that list Magnesium Oxide

195 foods in our catalog list it. These 60 list it highest on the label.

K9 Natural Chicken Feast Grain-Free Freeze-Dried Dog FoodK9 NaturalK9 Natural Chicken Feast Grain-Free Freeze-Dried Dog FoodFreeze-Dried // No. 13 on the labelNutriSource Grain-Free Large Breed Puppy Dry Dog FoodNutriSourceNutriSource Grain-Free Large Breed Puppy Dry Dog FoodDry // No. 15 on the labelBil-Jac Pate Platters Pâté Platters with Chicken & Vegetables Grain-Free Wet Dog FoodBil-JacBil-Jac Pate Platters Pâté Platters with Chicken & Vegetables Grain-Free Wet Dog FoodWet // No. 16 on the labelRoyal Canin Medium Dental Care Dry Dog FoodRoyal CaninRoyal Canin Medium Dental Care Dry Dog FoodDry // No. 16 on the labelNutriSource Small Bites Adult Chicken & Rice Recipe Dry Dog FoodNutriSourceNutriSource Small Bites Adult Chicken & Rice Recipe Dry Dog FoodDry // No. 16 on the labelHill’s Science Diet Adult Small & Mini Chicken & Barley Entrée Wet Dog FoodHill'sHill’s Science Diet Adult Small & Mini Chicken & Barley Entrée Wet Dog FoodWet // No. 17 on the labelK9 Natural Beef & Hoki Feast Grain-Free Freeze-Dried Dog FoodK9 NaturalK9 Natural Beef & Hoki Feast Grain-Free Freeze-Dried Dog FoodFreeze-Dried // No. 17 on the labelRoyal Canin Veterinary Hydrolyzed Protein PS Grain-Free Dry Dog FoodRoyal CaninRoyal Canin Veterinary Hydrolyzed Protein PS Grain-Free Dry Dog FoodDry // No. 17 on the labelRoyal Canin Small Dental Care Dry Dog FoodRoyal CaninRoyal Canin Small Dental Care Dry Dog FoodDry // No. 17 on the labelBil-Jac Chunky Stew with Chicken & Vegetables Grain-Free Wet Dog FoodBil-JacBil-Jac Chunky Stew with Chicken & Vegetables Grain-Free Wet Dog FoodWet // No. 18 on the labelRoyal Canin Small Indoor Senior Dry Dog FoodRoyal CaninRoyal Canin Small Indoor Senior Dry Dog FoodDry // No. 18 on the labelHill’s Prescription Diet d/d Salmon Skin Care Wet Dog FoodHill'sHill’s Prescription Diet d/d Salmon Skin Care Wet Dog FoodWet // No. 19 on the label
Show 48 more
NutriSource PureVita Grain-Free Salmon & Peas Entree Dry Dog FoodNutriSourceNutriSource PureVita Grain-Free Salmon & Peas Entree Dry Dog FoodDry // No. 17 on the labelNutriSource Grain-Free Large Breed Chicken & Pea Recipe Dry Dog FoodNutriSourceNutriSource Grain-Free Large Breed Chicken & Pea Recipe Dry Dog FoodDry // No. 17 on the labelNutriSource Large Breed Beef & Rice Recipe Dry Dog FoodNutriSourceNutriSource Large Breed Beef & Rice Recipe Dry Dog FoodDry // No. 17 on the labelNutriSource Grain-Free Small and Medium Breed Puppy Dry Dog FoodNutriSourceNutriSource Grain-Free Small and Medium Breed Puppy Dry Dog FoodDry // No. 17 on the labelK9 Natural Lamb Feast Grain-Free Freeze-Dried Dog FoodK9 NaturalK9 Natural Lamb Feast Grain-Free Freeze-Dried Dog FoodFreeze-Dried // No. 18 on the labelK9 Natural Lamb & Venison Feast Grain-Free Freeze-Dried Dog FoodK9 NaturalK9 Natural Lamb & Venison Feast Grain-Free Freeze-Dried Dog FoodFreeze-Dried // No. 18 on the labelNutriSource Grain-Free Chicken & Pea Recipe Dry Dog FoodNutriSourceNutriSource Grain-Free Chicken & Pea Recipe Dry Dog FoodDry // No. 18 on the labelNutriSource Grain-Free Small Bites Seafood Select Recipe Dry Dog FoodNutriSourceNutriSource Grain-Free Small Bites Seafood Select Recipe Dry Dog FoodDry // No. 18 on the labelNutriSource Grain-Free Lamb Meal & Peas Recipe Dry Dog FoodNutriSourceNutriSource Grain-Free Lamb Meal & Peas Recipe Dry Dog FoodDry // No. 18 on the labelNutriSource Super Performance Dry Dog FoodNutriSourceNutriSource Super Performance Dry Dog FoodDry // No. 18 on the labelNutriSource Grain-Free Seafood Select Recipe Dry Dog FoodNutriSourceNutriSource Grain-Free Seafood Select Recipe Dry Dog FoodDry // No. 18 on the labelNutriSource Grain-Free Small Bites Chicken & Pea Recipe Dry Dog FoodNutriSourceNutriSource Grain-Free Small Bites Chicken & Pea Recipe Dry Dog FoodDry // No. 18 on the labelNutriSource Beef & Rice Recipe Dry Dog FoodNutriSourceNutriSource Beef & Rice Recipe Dry Dog FoodDry // No. 18 on the labelNutriSource Large Breed Puppy Dry Dog FoodNutriSourceNutriSource Large Breed Puppy Dry Dog FoodDry // No. 18 on the labelK9 Natural Lamb & King Salmon Feast Grain-Free Freeze-Dried Dog FoodK9 NaturalK9 Natural Lamb & King Salmon Feast Grain-Free Freeze-Dried Dog FoodFreeze-Dried // No. 19 on the labelEukanuba Puppy Mixed Grill Chicken & Beef Dinner in Gravy Wet Dog FoodEukanubaEukanuba Puppy Mixed Grill Chicken & Beef Dinner in Gravy Wet Dog FoodWet // No. 19 on the labelEukanuba Puppy Small Breed Dry Dog FoodEukanubaEukanuba Puppy Small Breed Dry Dog FoodDry // No. 19 on the labelEukanuba Adult Beef & Vegetable Stew Wet Dog FoodEukanubaEukanuba Adult Beef & Vegetable Stew Wet Dog FoodWet // No. 20 on the labelEukanuba Adult Mixed Grill Chicken & Beef Dinner in Gravy Wet Dog FoodEukanubaEukanuba Adult Mixed Grill Chicken & Beef Dinner in Gravy Wet Dog FoodWet // No. 20 on the labelBil-Jac Harvest Feast with Turkey & Sweet Potatoes in Gravy Grain-Free Wet Dog FoodBil-JacBil-Jac Harvest Feast with Turkey & Sweet Potatoes in Gravy Grain-Free Wet Dog FoodWet // No. 20 on the labelHill’s Prescription Diet d/d Skin/Food Sensitivities Potato & Salmon Formula Grain-Free Dry Dog FoodHill'sHill’s Prescription Diet d/d Skin/Food Sensitivities Potato & Salmon Formula Grain-Free Dry Dog FoodDry // No. 20 on the labelHill’s Prescription Diet d/d Skin/Food Sensitivities Potato & Venison Formula Grain-Free Dry Dog FoodHill'sHill’s Prescription Diet d/d Skin/Food Sensitivities Potato & Venison Formula Grain-Free Dry Dog FoodDry // No. 20 on the labelNutriSource Grain-Free Senior Recipe Dry Dog FoodNutriSourceNutriSource Grain-Free Senior Recipe Dry Dog FoodDry // No. 20 on the labelNutriSource Grain-Free Weight Management Dry Dog FoodNutriSourceNutriSource Grain-Free Weight Management Dry Dog FoodDry // No. 20 on the labelNutriSource Weight Management Dry Dog FoodNutriSourceNutriSource Weight Management Dry Dog FoodDry // No. 20 on the labelNutriSource Large Breed Chicken & Rice Recipe Dry Dog FoodNutriSourceNutriSource Large Breed Chicken & Rice Recipe Dry Dog FoodDry // No. 20 on the labelEukanuba Puppy Dry Dog FoodEukanubaEukanuba Puppy Dry Dog FoodDry // No. 20 on the labelEukanuba Puppy Medium Breed Dry Dog FoodEukanubaEukanuba Puppy Medium Breed Dry Dog FoodDry // No. 20 on the labelEukanuba Adult Medium Breed Dry Dog FoodEukanubaEukanuba Adult Medium Breed Dry Dog FoodDry // No. 20 on the labelEukanuba Adult Small Bites Dry Dog FoodEukanubaEukanuba Adult Small Bites Dry Dog FoodDry // No. 20 on the labelArtemis Osopure Grain Free Chicken Formula Wet Dog FoodArtemisArtemis Osopure Grain Free Chicken Formula Wet Dog FoodWet // No. 21 on the labelArtemis Osopure Grain Free Lamb Formula Wet Dog FoodArtemisArtemis Osopure Grain Free Lamb Formula Wet Dog FoodWet // No. 21 on the labelRoyal Canin Veterinary Canine Renal Support Early Consult Dry Dog FoodRoyal CaninRoyal Canin Veterinary Canine Renal Support Early Consult Dry Dog FoodDry // No. 21 on the labelArtemis Osopure Grain Free Turkey & Salmon Wet Dog FoodArtemisArtemis Osopure Grain Free Turkey & Salmon Wet Dog FoodWet // No. 21 on the labelEukanuba Adult with Lamb & Rice Wet Dog FoodEukanubaEukanuba Adult with Lamb & Rice Wet Dog FoodWet // No. 21 on the labelRoyal Canin Size Health Nutrition Puppy Loaf in Sauce Wet Dog FoodRoyal CaninRoyal Canin Size Health Nutrition Puppy Loaf in Sauce Wet Dog FoodWet // No. 21 on the labelRoyal Canin Canine Care Nutrition Beauty Adult Loaf in Sauce Wet Dog FoodRoyal CaninRoyal Canin Canine Care Nutrition Beauty Adult Loaf in Sauce Wet Dog FoodWet // No. 21 on the labelRoyal Canin Veterinary Hydrolyzed Protein HP Dry Dog FoodRoyal CaninRoyal Canin Veterinary Hydrolyzed Protein HP Dry Dog FoodDry // No. 21 on the labelRoyal Canin Veterinary Satiety + Hydrolyzed Protein Dry Dog FoodRoyal CaninRoyal Canin Veterinary Satiety + Hydrolyzed Protein Dry Dog FoodDry // No. 21 on the labelRoyal Canin Small Adult 8+ Dry Dog FoodRoyal CaninRoyal Canin Small Adult 8+ Dry Dog FoodDry // No. 21 on the labelNutriSource Grain-Free Small Bites High Plains Select Recipe Dry Dog FoodNutriSourceNutriSource Grain-Free Small Bites High Plains Select Recipe Dry Dog FoodDry // No. 21 on the labelEukanuba Senior Medium Breed Dry Dog FoodEukanubaEukanuba Senior Medium Breed Dry Dog FoodDry // No. 21 on the labelEukanuba Senior Dry Dog FoodEukanubaEukanuba Senior Dry Dog FoodDry // No. 21 on the labelEukanuba Adult Dry Dog FoodEukanubaEukanuba Adult Dry Dog FoodDry // No. 21 on the labelRoyal Canin Comfort Care Loaf in Sauce Wet Dog FoodRoyal CaninRoyal Canin Comfort Care Loaf in Sauce Wet Dog FoodWet // No. 22 on the labelHill’s Adult Sensitive Stomach & Skin Chicken & Rice Stew Wet Dog FoodHill'sHill’s Adult Sensitive Stomach & Skin Chicken & Rice Stew Wet Dog FoodWet // No. 22 on the labelRoyal Canin Shih Tzu Loaf In Sauce Wet Dog FoodRoyal CaninRoyal Canin Shih Tzu Loaf In Sauce Wet Dog FoodWet // No. 22 on the labelRoyal Canin Veterinary Hydrolyzed Protein Moderate Calorie Dry Dog FoodRoyal CaninRoyal Canin Veterinary Hydrolyzed Protein Moderate Calorie Dry Dog FoodDry // No. 22 on the label

Sources

What we read

Checked September 1, 2026.

  1. 1 Protein digestibility evaluations of meat and fish substrates using laboratory, avian, and ileally cannulated dog assays Journal of Animal Science, 2010 // Journal
  2. 2 ACVIM Small Animal Consensus Recommendations on the Treatment and Prevention of Uroliths in Dogs and Cats Journal of Veterinary Internal Medicine, 2016 // Journal
  3. 3 Higher bioavailability of magnesium citrate as compared to magnesium oxide shown by evaluation of urinary excretion and serum levels after single-dose administration in a randomized cross-over study BMC Nutrition, 2017 // Journal
  4. 4 Magnesium oxide INRA CIRAD AFZ Feed Tables, n.d. // Database
  5. 5 AAFCO Dog and Cat Food Nutrient Profiles AAFCO, 2014 // Regulator
  6. 6 Feed material specification: Calcined magnesium oxide, CCM 85 SMZ Jelšava, 2022 // Industry
  7. 7 MAGOX Feed Grade Product Data Premier Magnesia, 2015 // Industry
  8. 8 Bioavailability of Mineral Supplements in Beef Cattle Nutrition Alabama Cooperative Extension System, 2021 // University
  9. 9 Toxicoses in Animals From Human Multivitamins and Supplements Merck Veterinary Manual, 2025 // Book
  10. 10 MagiCalm for Dogs Healthspan, n.d. // Industry
  11. 11 Reading Labels AAFCO, n.d. // Regulator
An ingredient on its own tells you very little. What matters is how much of it there is and where it sits in the list. That is why we weigh the top five rather than reacting to any single name further down. Back to the wiki

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