Expert Horse Advice

Feeding Sulfur to Horses

Dear HH:

I read the book Natural Horse Care by Pat Coleby and she gives a mixture of 50 lb Dolomite, 8 lb copper sulfate, 8 lb yellow dusting sulfur and 8 lb of seaweed meal as a free choice supplement on the range.  I then read your short blip on feeding sulfur for parasite control. I am having trouble finding sulfur to buy.

The one feed store that carries yellow dusting sulfur is telling me not to feed it to my animals, as their sales person is also saying that. I have read the Material Safety Data Sheets on all these chemicals but, is the small amount of sulfur that the animal would be ingesting just fine? Can you tell me if it is in fact yellow dusting sulfur that you are recommending being fed at 1 tsp per day?


Dear Heather:
Cysteine, Cystine, methionine and sulfur are components necessary in forming skin, hair, hooves, and other proteins.   Sulfur is an amino acid.  For equine use, seek only FEED GRADE organic in either the amino acid form, or supplied in MSM.  (Note: Free choice is your best option. MSM is more of a top dressing.)  To my knowledge there are no reports of symptoms of excess organic sulfur.

An excellent means to feed sulfur to your horse is "free choice" such as S-Mix (sold by, 1-800-373-5971).  S-Mix supplies 55% feed grade sulfur along with salt, which acts as a buffer.  Supply a variety of supplements free choice along with the S-Mix to allow your horse an opportunity to balance his/her needs naturally. 

Certified organic must be 100% organic.
Agricultural organic must be 95% organic (remaining 5% = vitamins/minerals).
Made with organic must be 70% organic.
Under the NOP (National Organic Program) organic must be 55%.

Dusting Sulfur is inorganic sulfur.  Generally it contains less than 0.15% sulfur, and is NOT FEED GRADE.  It is sold by farm/ranch ag retailers and in nurseries for the purpose of raising the acid level in soil to benefit plant growth.  Ag retailers also sell sulfur in blocks for ruminant animals.  Such animals chew cud and have a 4-chambered stomach.  In contrast, horses have a GI tract like a pig.  They have a small simple stomach and a small intestine, which lead to large sacs where bacterial fermentation takes place.  Additionally the horse?s stomach is very small compared to its size.  Neither the inorganic dusting powder nor the sulfated salt blocks are suitable for equine consumption!

There have been reports of over consumption of inorganic sulfur in horses.  With over 300g of inorganic sulfur fed, symptoms included lethargy, followed by colic and a yellow nasal discharge.  Yellowed eyes (jaundice) and labored breathing also followed.  Sadly, the sulfur toxicity was fatal for 2 horses.

Remember- never feed anything to your horse that is not FEED GRADE.  Rely on quality companies such as ABC (and other fine companies) to research ingredients for equine consumption.  When in doubt ASK before taking a risk.  Your horse's health depends on it!

Shari Frederick
Healthy Horse Hints


Category: Ask the Expert

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Opinions expressed herein are those of the experts consulted and do not necessarily represent the opinions of the editors and publishers. The information in this publication is for educational purposes only. It is not intended to medically prescribe or diagnose in any way. ~ Holistic Horse Inc.