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Source Plus — Dogs And Puppies (More than two decades ago SOURCE president and founder, Susan Domizi was…)

Source Plus

More than two decades ago SOURCE president and founder, Susan Domizi was competing on her eventing

Want to give your dog the same micronutrient edge horse owners have trusted for decades?

Reviewed by Ann Pruitt, InfoHorse.com · Updated April 2026
SOURCE Plus! for dogs seaweed micronutrient supplement 12 oz container
SOURCE Plus! for dogs seaweed micronutrient supplement 12 oz container
Source Plus For Dogs
SOURCE PLUS! Gives Dogs THE Micronutrient Edge...

What Makes Our Company Different?

More than two decades ago SOURCE president and founder, Susan Domizi was competing on her eventing horse, Hull, with hopes of being on the US Equestrian Olympic Team. "My horse [Hull] had hoof problems and couldn't maintain his body weight. He received the finest feeding program and veterinary care available. I suspected a nutrient deficiency and set out to find something to help him." She found a great deal of Norwegian and Japanese research on seaweeds that scientists and agriculturists here had been able to duplicate.

In addition to using information learned while earning a degree from Columbia University in New York, she studied all available data to determine what the American studies had missed. She used this information as a starting point for developing other approaches..

By trying different kinds of seaweeds, different blends, different methods of processing and constantly analyzing the findings she came up with a finely ground, dry mixture that she put in her horse's food. Her horse began to thrive. And that was the first serving of the product that was later to become SOURCE.

SOURCE PLUS! Gives Dogs THE Micronutrient Edge...

Dogs can thank horses for SOURCE PLUS! a nutritional advance that helps dogs cope with the consequences of increasing micronutrient deficiencies in their foods. Horsemen impressed with the results of adding SOURCE micronutrients to their horse's diet, reported similar improvements when they fed it to their dogs.

Now new SOURCE PLU S! formulated just for dogs provides the same all natural, broad-spectrum micronutrients from selected seaweeds plus the added benefits of yeast cultures, brewers yeast, garlic powder, vitamin E, zinc and natural beef flavor.

Depleted agricultural soils mean essential micronutrients are missing in even the finest dog foods. The SOURCE micronutrients are concentrated from seaweeds grown in nutrient-rich ocean waters. Careful selection, harvesting, and low temperature dehydration capture these nutrients at their peak. SOURCE PLUS! concentrates all the ocean's bounty and then adds other important natural ingredients to help young dogs grow strong and healthy and mature dogs feel their best. Dog owners' reports include superior glossy coats, healthy skin condition, successful breedings, and improved temperment and appetites.

What Is In Source Plus For Dogs?

Dehydrated seaweed meals, yeast culture, brewer's yeast, garlic powder, vitamin E, zinc proteinate, natural flavor carefully formulated to help bring optimal health and condition to your dog .

The Source Guarantee

We want every person to have the opportunity to see for themselves the effectiveness of the Source micronutrients found in all of our products. If you are not satisfied with any of the products for any reason, your money will be refunded in full - no strings attached. (Simply enclose proof of purchase.)

Order SOURCE PLUS For Your Dogs-- Today!

Every dog in the world can greatly benefit from the careful selection of ingredients that make up SOURCE PLUS for your dog. Be sure to order today-- also available at Amazon, Valleyvet and many fine dealers!




What Makes Our Company Different?

More than two decades ago SOURCE president and founder, Susan Domizi was competing on her eventing horse, Hull, with hopes of being on the US Equestrian Olympic Team. "My horse [Hull] had hoof problems and couldn't maintain his body weight. He received the finest feeding program and veterinary care available. I suspected a nutrient deficiency and set out to find something to help him." She found a great deal of Norwegian and Japanese research on seaweeds that scie

More than two decades ago SOURCE president and founder, Susan Domizi was competing on her eventing

Get in touch

Visit 4source.com


SOURCE Plus! for dogs seaweed micronutrient supplement 12 oz container
SOURCE Plus! for dogs seaweed micronutrient supplement 12 oz container

What exactly is SOURCE Plus! for dogs?

SOURCE Plus! is a daily micronutrient supplement built on a foundation of dehydrated ocean seaweed meals, then enriched with yeast culture, brewer's yeast, garlic powder, vitamin E, and zinc proteinate. Made by SOURCE micronutrients LLC, the same company that pioneered seaweed-based supplementation for performance horses, it delivers what the company calls broad-spectrum micronutrition rather than a single isolated nutrient. The formula contains no artificial colors, no synthetic flavoring, no preservatives, and no drugs, and is offered with a money-back satisfaction guarantee that carries "NO Time Limit."

SOURCE Plus! for dogs 5 lb bulk micronutrient supplement bucket
SOURCE Plus! for dogs 5 lb bulk micronutrient supplement bucket
Who makes it, and where did SOURCE come from?
SOURCE was founded in December 1975 by Susan Domizi, an analytically trained biochemist who began her horse career as a working student living in a hayloft. Her event horse, Hull, suffered persistent hoof problems and could not hold weight; an imported Irish seaweed product helped, but its quality was inconsistent, so Domizi drew on her science background to research seaweed meal and build a reliable, standardized supplement. She was the first in the horse industry to back her product with a money-back guarantee, and SOURCE today markets formulas for horses, dogs, and people worldwide. The company is a proud, founding member of the National Animal Supplement Council (NASC), audited and certified to display the NASC Quality Seal.

Layered ocean seaweed species used in SOURCE micronutrient blend
Layered ocean seaweed species used in SOURCE micronutrient blend

Why marine plants instead of land-grown ingredients?

SOURCE selects ocean seaweeds because, in the company's words, they contain "the broadest spectrum of micronutrients of any plants on earth in a highly concentrated form." Harvests from North Atlantic waters are scheduled at optimal growth cycles and processed to preserve the naturally occurring micronutrients. The premise behind the whole line is that decades of agricultural soil depletion have left commercial feeds and dog foods increasingly deficient in the trace elements, vitamins, and unidentified growth factors that marine plants concentrate so densely.

NASC Quality Seal certification for SOURCE micronutrients
NASC Quality Seal certification for SOURCE micronutrients

What results do dog owners report?

Owners using SOURCE Plus! report superior glossy coats, healthy skin condition, successful breedings, and improved temperament and appetites. Because micronutrients are involved in virtually every physiological process, the company frames the product as comprehensive nutritional support rather than a narrow coat-only or skin-only fix. The guaranteed analysis reflects that breadth, supplying zinc at 5,600 mg/kg, magnesium at 5,000 mg/kg, iodine at 350 mg/kg, iron at 250 mg/kg, plus naturally occurring potassium, sodium, calcium, copper, manganese, phosphorus, and a minimum 3,250 IU/kg of vitamin E.

How do you feed it, and which dogs is it for?
SOURCE Plus! is a dry meal that you simply stir into one daily feeding. Daily amounts scale by body weight, running from about 1 teaspoon for a 15-lb dog up to 2 tablespoons for dogs of 90 lb and over, so it suits everything from toy breeds to large working and sporting dogs. It is appropriate for breeding dogs, show and performance dogs, and ordinary household pets whose commercial diets may be missing trace micronutrients.

What does it cost and how do you order?

SOURCE Plus! for dogs is sold in a 12 oz. size at $16.47, a 5 lb. size, and a bulk 20 lb. size at $171.92, so an owner can start small and step up to economical bulk once results show. You can order directly through the company store at www.4source.com/shop/ or use the Dealer Locator to find a retailer. Questions about feeding or sizing can go to SOURCE customer service, Monday through Friday, 9am to 5pm ET.

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The Solution Section (FAQ)
How is Source Plus For Dogs different from SOURCE Original (canonical) and other SOURCE FOCUS products?

Per SOURCE, Inc.: distinct products in the SOURCE family.

  • SOURCE Original / Pelleted Original (canonical) — equine broad-spectrum micronutrient supplement
  • FOCUS HF / FOCUS SR / FOCUS WT (Wave 8 applied) — equine specialized formulations (hoof / senior / weight)
  • Source Plus For Dogs (this product) — canine-specific formulation

Same SOURCE micronutrient science; canine vs equine species split.

Where did Source Plus come from?

Per SOURCE: dogs can thank horses for SOURCE PLUS! Per the company: horsemen impressed with the results of adding SOURCE micronutrients to their horse's diet reported similar improvements when they fed it to their dogs. The new SOURCE PLUS! is formulated specifically for dogs.

What's in Source Plus that's specifically for dogs?

Per SOURCE Plus: provides the same broad-spectrum micronutrients from selected seaweeds as the equine SOURCE Original, PLUS canine-specific additions:

  • Yeast cultures
  • Brewers yeast
  • Garlic powder
  • Vitamin E
  • Zinc
  • Natural beef flavor
Why are micronutrients essential for dogs?

Per SOURCE: "Depleted agricultural soils mean essential micronutrients are missing in even the finest dog foods."

Per the company: SOURCE micronutrients are concentrated from seaweeds grown in nutrient-rich ocean waters. Careful selection, harvesting, and low-temperature dehydration capture nutrients at their peak.

Who is Susan Domizi — and what's the SOURCE founding story?

Per SOURCE: founder Susan Domizi was competing on her eventing horse Hull with Olympic Team hopes when Hull's hoof problems and weight maintenance challenges led her to suspect a nutrient deficiency. She found Norwegian and Japanese seaweed research, used her Columbia University degree, and developed the formula that became SOURCE. Source Plus is the canine extension of that work.

How do I order?

Per SOURCE, Inc.: Phone 800-232-2365, email [email protected], website http://www.4source.com. Pricing as quoted is subject to change.

What is SOURCE Plus! for dogs?
SOURCE Plus! is a daily, all-natural micronutrient supplement for dogs built on dehydrated ocean seaweed meals. It adds yeast culture, brewer's yeast, garlic powder, vitamin E, and zinc proteinate to the broad-spectrum seaweed base. It is made by SOURCE micronutrients LLC, the company that pioneered seaweed-based supplementation for horses.
What are the ingredients in SOURCE Plus! for dogs?
The formula contains dehydrated seaweed meals, yeast culture, brewer's yeast, garlic powder, vitamin E, zinc proteinate, and natural flavor. It contains no artificial colors, no synthetic flavoring, no preservatives, no synthetics, and no drugs.
What benefits do dog owners report from SOURCE Plus!?
Owners report superior glossy coats, healthy skin condition, successful breedings, and improved temperament and appetites. Because micronutrients participate in virtually every physiological process, the company positions SOURCE Plus! as comprehensive nutritional support rather than a single-benefit coat or skin product.
How much SOURCE Plus! do I feed my dog?
SOURCE Plus! is fed by body weight, mixed into one daily feeding. Daily amounts range from about 1 teaspoon for a 15-lb dog up to 2 tablespoons for dogs of 90 lb and over. It comes as a dry meal that you simply stir into the food.
Why does SOURCE use seaweed instead of land-grown plants?
SOURCE uses ocean seaweeds because, per the company, they contain the broadest spectrum of micronutrients of any plants on earth in a highly concentrated form. Harvests are scheduled at optimal growth cycles and specially processed to preserve naturally occurring micronutrients. Marine plants also avoid the micronutrient depletion seen in many agricultural soils.
Who founded SOURCE and why?
SOURCE was founded in December 1975 by Susan Domizi, a biochemically trained scientist who started in horses as a working student. Her event horse Hull had persistent hoof problems and couldn't hold weight; an imported Irish seaweed product helped but was inconsistent, so she researched and developed a reliable standardized seaweed supplement. She was the first in the horse industry to offer a money-back guarantee.
What sizes and prices does SOURCE Plus! for dogs come in?
SOURCE Plus! for dogs is offered in a 12 oz. size at $16.47, a 5 lb. size, and a 20 lb. bulk size at $171.92. Starting with the small size and moving to bulk once results appear is an economical approach.
How do I order SOURCE Plus! for dogs?
You can order directly from the company online store at www.4source.com/shop/, or use the SOURCE Dealer Locator to find a retailer near you. For help with sizing or feeding, call SOURCE customer service at 800-232-7365, Monday through Friday, 9am to 5pm ET.
Is SOURCE Plus! safe and quality-tested?
Yes. SOURCE is a founding member of the National Animal Supplement Council (NASC) and is audited and certified to display the NASC Quality Seal. Every component undergoes independent laboratory testing, including pesticide and herbicide residue analysis, heavy metal screening, and microbiological evaluation, with standards the company says exceed human food requirements.
How soon will I see results with SOURCE products?
SOURCE advises that visible benefits are rarely an overnight miracle because deficiencies develop over time. Reduced undigested matter often appears within days or weeks, and coat and condition changes follow as the body rebuilds. The company emphasizes steady, comprehensive nutrition over quick single-nutrient fixes.
Does SOURCE Plus! contain any GMO ingredients?
Original SOURCE and Micro-Max contain no GMO ingredients and never will. However, SOURCE Plus! and FOCUS products contain additional ingredients that may include GMOs, because most U.S. soybeans and field corn are now genetically modified. Owners seeking a strictly non-GMO option may prefer Original SOURCE.
What is the guaranteed analysis of SOURCE Plus! for dogs?
The guaranteed analysis lists zinc at 5,600 mg/kg, magnesium at 5,000 mg/kg, iodine at 350 mg/kg, iron at 250 mg/kg, copper at 5 mg/kg, manganese at 35 mg/kg, vitamin E at a minimum 3,250 IU/kg, potassium at 1.4%, sodium at 1.4%, phosphorus at 0.4%, and calcium at a 0.4% minimum to 0.9% maximum.
Can SOURCE be fed to dogs, cats, and other animals?
Yes. SOURCE Original powder has been used successfully across many species since 1975. The company suggests roughly 1/4 teaspoon of Original per 25 pounds of dog body weight, and 1/8 to 1/4 teaspoon for cats; SOURCE Plus! for dogs is the dog-specific, beef-flavored formulation with additional ingredients.
Is there a satisfaction guarantee?
Yes. SOURCE Plus! is backed by a money-back satisfaction guarantee that the company states has NO TIME LIMIT. Founder Susan Domizi was the first in the horse industry to offer a money-back guarantee, reflecting the company's stated commitment to quality control and respect for its customers.
Why is SOURCE Plus! described as 'broad-spectrum' rather than a hoof or coat product?
SOURCE defines micronutrients as the trace elements, vitamins, and unidentified substances essential to normal growth and development. Rather than mega-dosing one nutrient, SOURCE Plus! supplies a wide spectrum so the body can draw on what it needs across many physiological processes. The company notes it should not be necessary to mega-dose an individual vitamin to foster a normal response.
Does SOURCE Plus! help with skin, coat, and breeding specifically?
Owners frequently report glossy coats and healthy skin, as well as successful breedings and improved appetite and temperament. These outcomes are attributed to restoring micronutrients often missing from commercial diets grown on depleted soils, supporting whole-body condition rather than treating a single symptom.
Where can I learn more about SOURCE and its other products?
The official site at www.4source.com covers the full line, including formulas for horses, dogs, and people, plus an extensive FAQ and an Articles section on biotin, B vitamins, copper, zinc, enzymes, essential fatty acids, and chelated trace minerals. You can also reach the company directly at 800-232-7365 for product guidance.
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