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Ingredient file // Vitamin or mineral

Magnesium Sulfate

A mineral adjustment, not a health boost

Magnesium sulfate is a mineral salt added to help balance the magnesium in dog food. Magnesium is essential for normal muscle and metabolic function, but this ingredient line cannot tell you how much magnesium the finished food contains.

What it is
A soluble mineral salt that supplies magnesium and sulfate when measured into a dog food recipe.
Made from
Mineral deposits or reacted magnesium oxide
Main job
Adjusts dietary magnesium
Typical amount
Varies by recipe; labels give no amount
Watch for
Do not add Epsom salt yourself
Not the same as
Magnesium oxide

Straight answer

Is Magnesium Sulfate safe for dogs?

Read the nutrition statement, then move on

Magnesium sulfate among the mineral ingredients signals a recipe adjustment. Its place on the list cannot tell you the finished food's magnesium level. Check the nutritional adequacy statement for your dog's life stage. If your dog is on a urinary diet, follow its prescribed plan and assess the complete mineral profile.

Why it is in the food
Adjusts dietary magnesium

Our read // In our catalog

In 1 of every 9 foods we track

Share of foods that list it

11%

365 of the 3,205 foods with an ingredient list on file, from 42 brands. 287 wet dog food, 49 dry dog food, 15 dog food topper.

Each square is 1% of the catalog

Where it sits on the label

Median position 17. In the top five of 0 foods, so it is usually a minor ingredient.

Top five List position, heaviest first

Above the salt

16%

Usually listed after the salt, which caps it at roughly 1% of the recipe in 84% of foods.

Price per lb

Foods with it $3.58
All foods $3.25

Median of the cheapest bag price across 61 priced foods, 10% above the catalog. The price is the food's, not the ingredient's.

Who leans on it

16%

of the foods that list it are from Fromm. 42 brands use it in total.

What it is

How it is made

Producers obtain magnesium sulfate from evaporated seawater deposits or by reacting magnesium oxide with sulfuric acid. They refine the resulting salt into crystals or powder that is measured into animal feed.2,7

  1. 01 // Source Mineral or oxide Kieserite forms in marine salt deposits; magnesium oxide offers another raw material for making the salt.
  2. 02 // Process Dissolved or reacted Producers dissolve kieserite in water or react magnesium oxide with sulfuric acid.
  3. 03 // Process Crystallized and separated Magnesium sulfate crystallizes, then is separated from the remaining liquid, dried and sieved.
  4. 04 // Output Feed grade salt Crystals or powder are supplied for measured additions to animal feed, including pet food.

What is in it

Composition, dry matter

20.2

% magnesium

Magnesium in an anhydrous feed ingredient profile. The number describes the salt itself, not the magnesium concentration of a finished dog food.

Magnesium 20.2%6
Sulfur 26.6%6
Crude protein 0%6
Crude fat 0%6

This profile is for anhydrous magnesium sulfate. Producers also sell hydrated forms, whose water of crystallization changes the magnesium share by weight. An ingredient list does not identify the form used.2,6,8

Why it is in the bag

What the manufacturer gets

  1. 01

    Balances dietary magnesium

    A formulator can add this salt when the recipe's other ingredients do not provide enough magnesium for the finished food's nutrient target.2,3

  2. 02

    Mixes into the recipe

    The salt is sold as crystals or powder and dissolves readily in water. That makes it practical to distribute through a recipe; solubility alone does not show superior absorption in dogs.2

  3. 03

    Available at feed scale

    A supplier sells anhydrous magnesium sulfate specifically for livestock and pet nutrition in bags and bulk. That documents a manufacturing supply route, without showing a price advantage.7

How much The ingredient list gives no amount added; the useful figure is total magnesium in the finished food, measured against its nutrient target.3,8

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

    This salt supplies magnesium dogs need

    Evidence

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

    An anhydrous feed profile lists 20.2% magnesium, and the AAFCO dog food profiles set a 0.06% dry matter minimum. Magnesium sulfate can contribute toward that target; its presence does not reveal the finished food's magnesium level.3,6

  2. Brands say

    Extra magnesium makes dogs stronger and more energetic

    Outruns the evidence

    Evidence

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

    MSD describes lethargy and muscle weakness in magnesium deficient puppies, while AAFCO sets a 0.06% minimum for complete dog food. Those sources describe a requirement and deficiency signs; neither tests a performance boost from extra magnesium sulfate.3,4

  3. Owners say

    Magnesium sulfate in kibble prevents constipation

    Outruns the evidence

    Evidence

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

    MSD lists 5 to 25 g by mouth as an as needed laxative dose for dogs and calls laxative doses generally empirical. Its drug table gives no kibble inclusion amount, so it cannot support a constipation claim for this ingredient line.9

  4. Owners say

    Magnesium sulfate on a label causes bladder stones

    Outruns the evidence

    Evidence

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

    A 10-dog study tested a complete urinary diet alongside antibiotics; it did not isolate magnesium sulfate. UC Davis says canine struvite often accompanies infection and depends on urine conditions. The ingredient name alone does not show stone risk.1,5,8

Straight answers

What owners ask

  1. Q01

    Is it just filler?

    No

    It supplies magnesium, an essential mineral with a target in complete dog food. It supplies no protein or fat, but bulking up the recipe is not its job. Read it as a mineral adjustment.3,6

  2. Q02

    Is this Epsom salt?

    Same compound

    Epsom salt is the hydrated form of magnesium sulfate. The name on a food label does not say which form was used or how much was added. Do not use household Epsom salt to adjust a complete diet.2,4,8

  3. Q03

    Will it loosen my dog's stool?

    Label cannot tell

    Magnesium sulfate has a separate veterinary use as an oral laxative at 5 to 25 g. An ingredient list gives no dose, and the veterinary drug table does not evaluate its effect within a dog food recipe.8,9

  4. Q04

    Should dogs with stones avoid it?

    Not by name

    Stone care depends on the stone type, urine conditions and, for many dogs with struvite, infection. Ask the treating veterinarian about the finished food's mineral profile and prescribed plan instead of screening bags for this one salt.5,8

Who uses it

Brands, best sellers and the company it keeps

Top brands, by foods that list it

  1. Fromm 58 / 67
  2. Nulo 28 / 117
  3. Merrick 23 / 107
  4. Weruva 20 / 50
  5. Koha 19 / 29
  6. Purina 19 / 186
  7. Tiki Dog 14 / 30
  8. Dave's Pet Food 11 / 22
  9. ZIWI 11 / 11
  10. Wellness 11 / 118

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

Plus 32 more brands.

Amazon best sellers that list it

  1. #58 Purina Pro Plan All Ages Sport Performance 30/20 Chicken & Rice Formula Dry Dog Food
  2. #60 Fromm Four-Star Beef Frittata Veg® Recipe Grain-Free 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 56%
  2. Carrots 44%
  3. Chicken Broth 34%
  4. Beef 29%
  5. Sunflower Oil 27%
  6. Pumpkin 22%
  7. Potassium Chloride 22%
  8. Dried Egg Product 22%
  9. Salt 21%
  10. Brown Rice 21%
  11. Potatoes 20%
  12. Guar Gum 20%

On the shelf

Foods that list Magnesium Sulfate

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

Dave’s Pet Food Pouches Dave’s Chicken & Salmon with Brown Rice, Goat Milk Pouch Recipe for Do Wet Dog FoodDave's Pet FoodDave’s Pet Food Pouches Dave’s Chicken & Salmon with Brown Rice, Goat Milk Pouch Recipe for Do Wet Dog FoodWet // No. 8 on the labelFromm Four-Star Diner Specials Slow-Cooked Pulled Pork Entrée in Gravy Wet Dog FoodFrommFromm Four-Star Diner Specials Slow-Cooked Pulled Pork Entrée in Gravy Wet Dog FoodWet // No. 8 on the labelPedigree High Protein Adult Can, Chicken & Turkey Wet Dog FoodPedigreePedigree High Protein Adult Can, Chicken & Turkey Wet Dog FoodWet // No. 8 on the labelDave’s Pet Food Pouches Dave’s Beef & Chicken with Brown Rice, Goat Milk Pouch Recipe Wet Dog FoodDave's Pet FoodDave’s Pet Food Pouches Dave’s Beef & Chicken with Brown Rice, Goat Milk Pouch Recipe Wet Dog FoodWet // No. 9 on the labelZiwi Chicken Grain-Free Wet Dog FoodZIWIZiwi Chicken Grain-Free Wet Dog FoodWet // No. 9 on the labelFromm Four-Star Diner Classics Charlie’s Chicken Pot Pie Pâté Wet Dog FoodFrommFromm Four-Star Diner Classics Charlie’s Chicken Pot Pie Pâté Wet Dog FoodWet // No. 9 on the labelPedigree Choice Cuts IN Gravy Adult Can, Beef Wet Dog FoodPedigreePedigree Choice Cuts IN Gravy Adult Can, Beef Wet Dog FoodWet // No. 9 on the labelPurina Pro Plan Sensitive Skin & Stomach Salmon & Rice Entrée Classic Wet Dog FoodPurinaPurina Pro Plan Sensitive Skin & Stomach Salmon & Rice Entrée Classic Wet Dog FoodWet // No. 9 on the labelBlue Wilderness Wild Meals Chicken & Sweet Potato Wet Dog FoodBlueBlue Wilderness Wild Meals Chicken & Sweet Potato Wet Dog FoodWet // No. 9 on the labelWeruva Dogs in the Kitchen BFF Fun Size Meals Oh So Nice Sirloin Tips & Rice Wet Dog FoodWeruvaWeruva Dogs in the Kitchen BFF Fun Size Meals Oh So Nice Sirloin Tips & Rice Wet Dog FoodWet // No. 10 on the labelWeruva Dogs in the Kitchen BFF Fun Size Meals I’m In Luck With Duck & Rice Wet Dog FoodWeruvaWeruva Dogs in the Kitchen BFF Fun Size Meals I’m In Luck With Duck & Rice Wet Dog FoodWet // No. 10 on the labelIams Adult Chicken Chunks IN Gravy Wet Dog FoodIamsIams Adult Chicken Chunks IN Gravy Wet Dog FoodWet // No. 10 on the label
Show 48 more
Dave’s Pet Food Dave’s Grain-Free Goat Milk, Chicken Dinner Pouch Recipe for Dogs / 10 Wet Dog FoodDave's Pet FoodDave’s Pet Food Dave’s Grain-Free Goat Milk, Chicken Dinner Pouch Recipe for Dogs / 10 Wet Dog FoodWet // No. 10 on the labelFromm Four-Star Pâté Chicken & Rice Pâté Wet Dog FoodFrommFromm Four-Star Pâté Chicken & Rice Pâté Wet Dog FoodWet // No. 10 on the labelFromm Pâté Beef & Barley Pâté Wet Dog FoodFrommFromm Pâté Beef & Barley Pâté Wet Dog FoodWet // No. 10 on the labelFromm Pâté Lamb Pâté Wet Dog FoodFrommFromm Pâté Lamb Pâté Wet Dog FoodWet // No. 10 on the labelFromm Pâté Lamb & Sweet Potato Pâté Wet Dog FoodFrommFromm Pâté Lamb & Sweet Potato Pâté Wet Dog FoodWet // No. 10 on the labelOpen Farm Icelandic Salmon & Capelin Grain-Free Wet Dog FoodOpen FarmOpen Farm Icelandic Salmon & Capelin Grain-Free Wet Dog FoodWet // No. 10 on the labelPedigree High Protein Adult Can, Beef & Lamb Wet Dog FoodPedigreePedigree High Protein Adult Can, Beef & Lamb Wet Dog FoodWet // No. 10 on the labelPedigree Choice Cuts IN Gravy Adult Cans, Country Stew and Chicken & Rice Wet Dog FoodPedigreePedigree Choice Cuts IN Gravy Adult Cans, Country Stew and Chicken & Rice Wet Dog FoodWet // No. 10 on the labelPedigree Choice Cuts IN Gravy Adult Can, Country Stew Wet Dog FoodPedigreePedigree Choice Cuts IN Gravy Adult Can, Country Stew Wet Dog FoodWet // No. 10 on the labelPurina Pro Plan Puppy Starter Chicken Entrée Ultra Soft Mousse Wet Dog FoodPurinaPurina Pro Plan Puppy Starter Chicken Entrée Ultra Soft Mousse Wet Dog FoodWet // No. 10 on the labelBlue Wild Meals High Protein Turkey Chicken Sweet Potato Feast Wet Dog FoodBlueBlue Wild Meals High Protein Turkey Chicken Sweet Potato Feast Wet Dog FoodWet // No. 10 on the labelMerrick Grain Free Limited Ingredient Lamb Wet Dog FoodMerrickMerrick Grain Free Limited Ingredient Lamb Wet Dog FoodWet // No. 10 on the labelPurina Pro Plan Puppy Small Breed Chicken & Brown Rice Entrée Wet Dog FoodPurinaPurina Pro Plan Puppy Small Breed Chicken & Brown Rice Entrée Wet Dog FoodWet // No. 11 on the labelDave’s Pet Food Bland Diet Pouches Dave’s Bland Duck & Pumpkin Pouch Recipe for Dogs / 10 Pack - Pou Wet Dog FoodDave's Pet FoodDave’s Pet Food Bland Diet Pouches Dave’s Bland Duck & Pumpkin Pouch Recipe for Dogs / 10 Pack - Pou Wet Dog FoodWet // No. 11 on the labelZiwi Air-Dried Chicken Dog Food TopperZIWIZiwi Air-Dried Chicken Dog Food TopperTopper // No. 11 on the labelBil-Jac Picky No More Pâté with Chicken & Chicken Liver Wet Dog FoodBil-JacBil-Jac Picky No More Pâté with Chicken & Chicken Liver Wet Dog FoodWet // No. 11 on the labelIams Adult Beef Chunks IN Gravy Wet Dog FoodIamsIams Adult Beef Chunks IN Gravy Wet Dog FoodWet // No. 11 on the labelIams Adult Lamb Chunks IN Gravy Wet Dog FoodIamsIams Adult Lamb Chunks IN Gravy Wet Dog FoodWet // No. 11 on the labelFromm Pâté Chicken & Duck Pâté Wet Dog FoodFrommFromm Pâté Chicken & Duck Pâté Wet Dog FoodWet // No. 11 on the labelFromm Pâté Chicken & Sweet Potato Pâté Wet Dog FoodFrommFromm Pâté Chicken & Sweet Potato Pâté Wet Dog FoodWet // No. 11 on the labelFromm Pâté Salmon & Chicken Pâté Wet Dog FoodFrommFromm Pâté Salmon & Chicken Pâté Wet Dog FoodWet // No. 11 on the labelFromm Classic Adult Turkey & Rice Pâté Wet Dog FoodFrommFromm Classic Adult Turkey & Rice Pâté Wet Dog FoodWet // No. 11 on the labelFromm Four-Star Diner Specials Chicken Canine Bleu Entrée in Gravy Wet Dog FoodFrommFromm Four-Star Diner Specials Chicken Canine Bleu Entrée in Gravy Wet Dog FoodWet // No. 11 on the labelFromm Four-Star Diner Classics Paula’s Chicken & Pumpkin Pâté Wet Dog FoodFrommFromm Four-Star Diner Classics Paula’s Chicken & Pumpkin Pâté Wet Dog FoodWet // No. 11 on the labelFromm Classic Puppy Chicken & Salmon Pâté Wet Dog FoodFrommFromm Classic Puppy Chicken & Salmon Pâté Wet Dog FoodWet // No. 11 on the labelPedigree Small Dog Food with Tender Bites, Steak & Vegetable Wet Dog FoodPedigreePedigree Small Dog Food with Tender Bites, Steak & Vegetable Wet Dog FoodWet // No. 11 on the labelPedigree Choice Cuts IN Gravy Adult Can, Prime Rib, Rice, and Vegetable Wet Dog FoodPedigreePedigree Choice Cuts IN Gravy Adult Can, Prime Rib, Rice, and Vegetable Wet Dog FoodWet // No. 11 on the labelPedigree Choice Cuts IN Gravy Adult Can, Steak & Vegetable Wet Dog FoodPedigreePedigree Choice Cuts IN Gravy Adult Can, Steak & Vegetable Wet Dog FoodWet // No. 11 on the labelMerrick Lil’ Plates Petite Pates Lamb Grain-Free Wet Dog FoodMerrickMerrick Lil’ Plates Petite Pates Lamb Grain-Free Wet Dog FoodWet // No. 11 on the labelCesar Filets in Gravy Wood-Grilled Chicken Wet Dog FoodCesarCesar Filets in Gravy Wood-Grilled Chicken Wet Dog FoodWet // No. 11 on the labelCesar Mini Pouches Filets in Gravy Angus Beef Mini-Pouch Wet Dog FoodCesarCesar Mini Pouches Filets in Gravy Angus Beef Mini-Pouch Wet Dog FoodWet // No. 11 on the labelCesar Mini Pouches Rotisserie Chicken Mini-Pouch Wet Dog FoodCesarCesar Mini Pouches Rotisserie Chicken Mini-Pouch Wet Dog FoodWet // No. 11 on the labelTruDog Elevate Smoky BBQ Stew Grain Free Shredded Chicken Stew w/ Sweet Potat Wet Dog FoodTruDogTruDog Elevate Smoky BBQ Stew Grain Free Shredded Chicken Stew w/ Sweet Potat Wet Dog FoodWet // No. 12 on the labelBIXBI RAWBBLE Grain-Free Wet Dog FoodBIXBIBIXBI RAWBBLE Grain-Free Wet Dog FoodWet // No. 12 on the labelDave’s Pet Food Dave’s Bland Beef & Rice Pouch Recipe for Dogs / 10 Pack - Pouche Wet Dog FoodDave's Pet FoodDave’s Pet Food Dave’s Bland Beef & Rice Pouch Recipe for Dogs / 10 Pack - Pouche Wet Dog FoodWet // No. 12 on the labelZiwi Beef Grain-Free Wet Dog FoodZIWIZiwi Beef Grain-Free Wet Dog FoodWet // No. 12 on the labelKoha Pure Shreds Shredded Chicken Breast Dog Entrée Wet Dog FoodKohaKoha Pure Shreds Shredded Chicken Breast Dog Entrée Wet Dog FoodWet // No. 12 on the labelKoha Pure Shreds Shredded Duck Entrée Wet Dog FoodKohaKoha Pure Shreds Shredded Duck Entrée Wet Dog FoodWet // No. 12 on the labelKoha Pure Shreds Shredded Beef Entrée Wet Dog FoodKohaKoha Pure Shreds Shredded Beef Entrée Wet Dog FoodWet // No. 12 on the labelKoha Duck Entrée : Limited Ingredient Diet Wet Dog FoodKohaKoha Duck Entrée : Limited Ingredient Diet Wet Dog FoodWet // No. 12 on the labelKoha Limited Ingredient Bland Diet Lamb & Rice Recipe Wet Dog FoodKohaKoha Limited Ingredient Bland Diet Lamb & Rice Recipe Wet Dog FoodWet // No. 12 on the labelKoha Limited Ingredient Bland Diet Beef & Rice Recipe Wet Dog FoodKohaKoha Limited Ingredient Bland Diet Beef & Rice Recipe Wet Dog FoodWet // No. 12 on the labelInaba Churu Meal in Gravy Chicken Recipe with Vegetables Grain-Free Wet Dog FoodINABAInaba Churu Meal in Gravy Chicken Recipe with Vegetables Grain-Free Wet Dog FoodWet // No. 12 on the labelInaba Churu Meal Chicken Recipe Grain-Free Dog Food TopperINABAInaba Churu Meal Chicken Recipe Grain-Free Dog Food TopperTopper // No. 12 on the labelInaba Churu Meal Chicken with Beef Recipe Grain-Free Dog Food TopperINABAInaba Churu Meal Chicken with Beef Recipe Grain-Free Dog Food TopperTopper // No. 12 on the labelWellness Core 95% Chicken & Broccoli Grain-Free Wet Dog FoodWellnessWellness Core 95% Chicken & Broccoli Grain-Free Wet Dog FoodWet // No. 12 on the labelFromm Four-Star Pâté Beef & Sweet Potato Pâté Grain-Free Wet Dog FoodFrommFromm Four-Star Pâté Beef & Sweet Potato Pâté Grain-Free Wet Dog FoodWet // No. 12 on the labelHalo Elevate Smoky BBQ Stew Grain Free Shredded Chicken Stew w/ Sweet Potat Wet Dog FoodHaloHalo Elevate Smoky BBQ Stew Grain Free Shredded Chicken Stew w/ Sweet Potat Wet Dog FoodWet // No. 12 on the label

Sources

What we read

Checked October 25, 2026.

  1. 1 Evaluation of a dry therapeutic urinary diet and concurrent administration of antimicrobials for struvite cystolith dissolution in dogs BMC Veterinary Research, 2019 // Journal
  2. 2 Magnesium Sulfate: Chemical and Technical Assessment Joint FAO/WHO Expert Committee on Food Additives, 2007 // Regulator
  3. 3 AAFCO Dog Food Nutrient Profiles Based on Dry Matter AAFCO, 2013 // Regulator
  4. 4 Nutritional Requirements of Small Animals MSD Veterinary Manual, 2024 // Book
  5. 5 Nutritional Management of Uroliths University of California, Davis School of Veterinary Medicine, 2019 // University
  6. 6 Magnesium Sulfate Anhydrous Mad Barn FeedBank, n.d. // Database
  7. 7 KaSa Mag98® K+S Aktiengesellschaft, n.d. // Industry
  8. 8 Reading Labels AAFCO, n.d. // Regulator
  9. 9 Cathartic and Laxative Drugs Used in Monogastric Animals MSD Veterinary Manual, 2024 // Book
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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