Feeding Flaxseed

Is this plant safe to feed your horse?

Is this plant safe to feed your horse?

By Dr. Thomas R. Lenz

A horse owner recently sent The American Quarter Horse Journal a column from a horse magazine pointing out potential toxic effects of feeding flaxseed to horses. Because flaxseed is commonly fed as a supplement, I thought it would be a good idea to look into the issue. Here is what I have learned.

The Plant

Flax is a small, blue-flowered plant that grows throughout the United States. The plant contains cyanogenic glycosides that can produce highly toxic hydrogen cyanide (prussic acid) if the plant cells are damaged. This occurs most frequently when a cold snap freezes the plans. Cyanide contained in the damaged leaves affects the animal’s respiratory system and can cause sudden death. Other plants that can produce cyanide after sudden damage to their leaves include sweet peas, sudan grass, Johnson grass, sorghum and white clover.

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Flax produces a tiny seed that is commonly fed to livestock. It has also become popular in human diets because it is thought to lower serum cholesterol, prevent heart disease, lower blood pressure, improve skin quality and stimulate the body’s immune response. Some studies in laboratory animals suggest that it can also aid in the treatment and/or prevention of some forms of cancer.

Because the tiny flaxseed is hard and difficult to chew, most of it goes undigested if it is not processed prior to feeding. Traditionally, flaxseed has been crushed to produce linseed oil and the resultant flaxseed (also called linseed) meal has been used as a protein supplement for livestock.

Similar to most grains, the composition of flax can vary based on variety, environmental factors and methods of analysis. But generally, flaxseed contains 42 percent oil, 20 percent protein and 28 percent dietary fiber. Flaxseed also contains high concentrations of Omega 3 fatty acids, which horses need to maintain good health. Omega 3 fatty acids are not produced by the body and must be obtained through the horse’s diet.

Research conducted at the University of Guelph demonstrated that horses suffering from sweet itch, a common skin disease caused each summer by Culicoides insects (midges), improved dramatically following daily supplementation of their diet with one pound of milled flaxseed. Other benefits of flaxseed supplementation include stimulation of the immune system, relief of arthritis and reduction of pain due to inflammation, an increase in the ability of cells to take up oxygen, improved skin and hair coat and scavenging of free radicals. Because it is high in dietary fiber, it can also help prevent impaction and sand colics.

Whole flaxseed, as opposed to milled flaxseed that has been ground, should be soaked in cold water for two to six hours and then boiled for 10 to 30 minutes to soften it and destroy any prussic acid that might be present. It is then fed, about ¼ cup (measured dry before soaking), as part of a bran mash once or twice a week per horse per feeding. The whole seed keeps well in storage for a long time, but ground flax will deteriorate fairly quickly. Many of the newer horse feeds contain milled flaxseed or linseed meal that will be listed on the label.

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There has been some concern that flaxseed causes hypothyroidism in horses, but I could not find a reliable source that confirmed this fear. Hypothyroidism is poorly understood in the horse. AQHA is funding research to learn more about the disease.

It also appears that although the flax plant can become toxic if severely damaged by an early frost, the seed and oil are relatively safe if fed in small amounts. As discussed earlier, the seed can always be boiled to destroy any toxic prussic acid if you’re concerned about feeding flaxseed.

If you have any questions on flaxseed supplementation, talk to your local university extension equine nutritionist.

For more information on keeping your horse healthy, consult an American Association of Equine Practitioners-member veterinarian in your area. For a list of members, go to www.myhorsematters.com or call (800) GETADVM.

43 thoughts on “Feeding Flaxseed”

  1. Could you tell me how safe Kelp is for horses, I was informed by a trainer that Kelp supplement helps the horses coat, is that really true, what is the pros and cons, also what is the comparison with flaxseed.

    Lisa G.

  2. Thank you for the info on the Flaxseed plant itself. I had no idea it was toxic, and I have alot of it just outside my pasture gate. My horse doesnt seem particulary fond of the plant, and doesnt grab at it like he would grass growing outside the gate. I live in a mountain valley and I am sure the plants near my gate have been in a toxic state. I will know now to keep my horse away from the plants after the first hard freeze. FYI:These plants multiply rapidly and might be hard to get rid of. The plants seem to die after two years of blooming around my place, but are rapidly replaced by the other self seeding plants.

  3. I feed ground flax to all my horses for years now. I give 1 cup in the Am and 1 cup in the PM with their supplements. They all have a beautiful shine. And i believe they have a stronger immune system.

  4. Regarding the feeding of flaxseed. Old time horsemen knew to soak the flaxseed then boil/simmer it. The seed and water was added to make a bran mash along with salt and a half cup of molasses. I still do it that way.

  5. I read somewhere that the seed contains cyanide and should not be fed whole unless cooked or ground, once the seed is broken then the cyanide is released. I always buy whole seed and grind it just before I go out to feed, I keep it in a burr coffee grinder and grind the amount I need for that feeding, it is a convenient way of feeding ground flax.

  6. A.m. & p.m. I feed: 1/4 C whole flax seeds, 1/4 C stabilized rice bran meal, Nutrena’s Safe Choice (about 2 cups)&, now that it’s so cold & we’ve had one case of colic, electrolytes.

    Are the flax seeds, un-ground, doing any good? Are they doing any harm? At the price, if they’re ineffective or dangerous, I’ll quit feeding it asap.


  7. I started both my horses on flaxseed last year before show season. We kept both horses under the same lights . . blankets etc. but the one horse with sensitive skin grew a very thick hair coat! He looked liked he had been outside in the winter under no blankets or lights! As soon as we took him off of it, he started to lose his hair and go back to his slick show coat. The other horse showed no differences at all. Has anyone else experienced this with flaxseed?

  8. I have three Quarter horses, a 4 year old gelding, a 15 year old gelding and a 24 year old mare. All three of my horses get ground flax seed everyday for all the reasons listed (immunue system, digestive, improved skin and coat). Just in case you want an easier way to feed flax seed is to go to http://www.horsetech.com as they sell ground flax seed! It is a little more expensive than buying it whole and grinding it your self but it has a stablizer in it and with three horses I buy it in a 40 lb bag. They also sell it in smaller quanties if you don’t need that much.

  9. The plant is unsafe when it turns RED. All the other grasses that are poisonous … sweet peas, sudan grass, Johnson grass, sorghum and white clover… turn red when they are producing prussic acid. Every farmer who grows those grasses, knows to keep the cows off after the first frost and during periods of drought. Whenever they find a dead cow, it is in the red grass area, not the green area.

  10. My friend where I keep my colt feeds flax seed, soy meal,mineral
    with the mix grain. When I picked my mare up from where she
    was boarded before, she was in poor condition, I brought her to
    my friend’s place and within a week to two months, she improved gained weight her coat was glistening. She had two foals at
    my friend’s from her stallion and the babies were excellent,
    all from the feed, the flax seed. Now my colt that I have left
    from my mare(I have since sold the mare) looks good, even tho
    he gets muddy, I can curry him and he looks beautiful. He is a

  11. Kelp is iodine it is good for alot of things, it is helpful
    suppressing cysts in humans, also epilepsy, I give it to my
    cat and it has helped her. If you want more info on it you can e-mail me at:cowgirlupjani@msn.com.

  12. I feed what appears, compared to the other e-mails, a very small amount of ground flax seed to my horses feed. Does anyone actually know if there is a correct way to determine how much should be top dressed?

  13. I have been grinding flax seed for over a year now. My mare got a horrible case of the hives that would last approx. 7 wks 2 or 3 times within the year. I started her on the flax seed.I never found out what was giving them to her, but this year no hives.

  14. We have been feeding whole flax for the last 30 years to the horses we are working and the one’s we are showing and getting ready for sale’s we feed app one half pound two times per day I agree ground is quite likely more palable but we try to keep our costs down and feeding whole raw flax is two thirds the cost of proosesed flax and is been doing the job for a long time Ken

  15. To Carol who fed her mare Flax seed for hives. How much did you give your mare and how long did it take until you saw improvement in the hives? Did you use ground Flax see and did you use any thing else to the mix? We have a horse that gets bad hives also.

  16. For Pam,

    Ground flax seed is good but I recommend Equi-Derm from Riva’s Remedies in Armstrong, BC, Canada. Her products are amazing, all natural and I have had great results with that one in particular for any skin conditions.

  17. Hello,
    My fourteen mare sprained her hamstring two weeks ago and is now just able to walk slowly around the barn. Someone told me to give her bromelain to reduce swelling. What about flaxseed powder? Does this work also to reduce swelling around the hock? Thank you.

  18. Hello,
    My fourteen year old mare sprained her hamstring two weeks ago and is now just able to walk slowly around the barn. Someone told me to give her bromelain to reduce swelling. What about flaxseed powder? Does this work also to reduce swelling around the hock? Thank you.

  19. I was told the horse would get more benefit out of flaxseed oil vs ground flax seed.anyone know for sure?

  20. Hi… I feed my horses ground flax everyday. They are doing very well with it. I also make horse treats with it. I have a commercial grinder and would gladly grind it and ship it to anyone out there that wants it. Just email me and let me know how much you need and we can discuss the price. maggiero123@gmail.com

  21. I have been feeding my horses whole flax seed for many years and they are doing wonderful. I put about 1/4 cup in water with alfalfa cubes in the morning and then feed them it at night with there grain. (It is very oily by then) All the horses coats are shiny and the they all seem quite healthy. I saw a big difference in the horses after several months when I first started them on it. One note I want to ad is that I have an old dog that comes to the barn with me and he suffers from arthritis. He likes to lick the empty buckets that I keep the flax and alfalfa in after I have feed it to the horses and I must say that after several months of him doing this he is a changed dog. He runs and plays constently now, like he did when he was about 7. ( he is about 15 now)HUGE change in him.

  22. Our family has been using flax seed in our diets here for many years. I think it woulkd be safe to assume that by grinding our organic flax sees and feeding it, any horse would be safe from the toxic effects of prussic acid. Organic flax seed is very econimic to buy. Well worth it in the end.

  23. Good Afternoon,

    Just brought a bag of grounded flaxseed for my horses. After reading the article above do I need to soak the grounded flaxseed before giving it to my girls and secondly, I planned to feed them in small portion. My youngest mare gets to skin irritation were she rub herself against board, tree etc. I was told that the flaxseed will assist with this problem ans well as helping her immune system and coats.

    Thank you for your assistance.

  24. Hello,
    So I am kinda confused, Is feeding whole flax seed alright for horses? My horse has a history of collic so she was put on sandclear at a young age. She hasn’t colliced since but someone told me I should start giving her flax seed. They told me it would also be good for her coat. I just don’t want anything to hurt her as she is already 17 almost 18. I have been doing some research and hears MANY different things said about feeding flax… she is 15.1 but is pretty stocky. She is boarded at a friends barn so I dont want to cause her too much pain feeding this but I wouldn’t mind starting her on it. Also, would feeding flax seed from a grocery store for people be aright? I mean is it the same thing? No feed store around me has flax right now so Im trying to figure out something. And would feeding flax hurt her while she is on sandclear? Could I still give her the sandclear? That is the only other suppliment she has besides a splash of corn oil. Any suggestions?!

  25. Everyone, thanks for your comments on this post. Because of the popularity of the flaxseed/supplement subject, I’m going to ask Dr. Lenz if he’s willing to do a follow-up article to answer all your questions. I’ll let you know when you can expect it!

    Best wishes, and happy riding.

    Jody Reynolds
    AQHA Internet Editor

  26. I was told that feeding flax seed to your horses could cause kidney and liver problems with them, I need to know if this is true because some people tell me that it is not true. Could you please clear this up for me, my friends and I are looking to giving it to them but we want to know if there is any fact in this. Please help us.

  27. My Paint mare had horrible allergic reactions to tick bites. After asking/reading around I decided to add 1/2 cup of ground flax to her morning feed. WOW what an amazing difference! We are dilligent in tick/fly control at our barn, but the occasional bite slips through. My mare doesn’t have any greater reaction to it than any other horse since I added the flax. In the summer I pre-bag her supplements and keep them refrigerated to keep the flax fresh. It works amazingly well!

  28. When flax is ground it is only good for about 15-20 mins. It makes perfect sense to purchase a small coffee grinder and grind as needed. Keep whole seeds in frig for freshness. Read Dr Budwig’s research on the correct use of flax seed and it does help with many aliments. Going to add to horse and dogs diet!

  29. I have decided to start feeding my horses flaxseed. I’ve been researching online and it’s a 50/50 on how to feed it. Half the sites say to feed it whole, not boiled, not soaked (for the reason that the 2 components in cyanide are in it and boiling/soaking them will combine the 2 and make cyanide) and not grinded (loss of nutrients when grinded) and they also say that salyva etc. Will break down the 2 components of cyanide before it gets a chance to become cyanide.

    What are your thoughts?

  30. I havent seen anyone discuss feeding organic flaxseed oil instead of the milled or whole flaxseeds. Is it safe to feed the flaxseed oil and what is the correct dosage for a horse?

  31. I only feed ground whole flaxseed during the summer months. I’ve never soaked it. I start them on it at the beginning of spring to help shed them out because it gets so hot here so fast and it leaves them nice and shiny. I have been doing this for years and have never had any problems. In the 46 years I’ve had horses I have had only 1 mild colic. Knock on wood. Once whole flax is ground it loses 10% of it’s nutritional value. The longer it sits as ground the more it loses. So for those who are buying ground flaxseed you’re wasting your money. get a coffee grinder and grind your own as needed. I use a holistic vet that highly recommends ground flaxseed as part of a horses diet.

  32. I have been feeding ground flaxseed to 4 of my horses for a year now. I buy a 50 lb. bag and grind it using a Black and Decker Coffee grinder I bought at Fry’s market place. You can fill it with a cup of seed and turn it on and let it grind away. I tried feeding whole seed initially. Found that when I did, my stalls were full of birds eating the seeds that the horses didn’t digest. They made a mess of my stalls, spreding the poop everywhere to get to all the seeds. That is when I turned to grinding it. I grind a 5 lb bucket once a week and keep it in the fridge to prevent it from going rancid. I started this per the recommendation of a vet because I have a tall 4 white socked paint gelding that was getting scratches every summer for the last 4 summers. After salves, medications, steroids and endless days of not riding because his legs hurt so bad he was lame, I was willing to try anything. This summer, NO scratches. All of my horses have amzing coats that shine with minimal grooming! Also found that they rub their manes and tails less during the summer now that I have them on the ground flaxseed. I feed a 4 oz. scoop once a day with their ultium and rice bran lunch bucket.

  33. The Facts:
    There are three basic quality standards for flaxseed.
    1. Industrial (used for making paint thinner, etc..)
    2. Feed , O.K. for feeding to “animals”
    3. Human grade , safe for feeding to people

    Not a lot of information about this on the internet, but if you can find the “human grade”, it has a lot lower percentage of the bad chemicals in it, and is thus much safer to feed.

    The OLD traditional reason for feeding flaxseed was for keeping the intestinal tract clean (colic prevention), and for a nice shiny coat. Unfortunately the “old” tradition of soaking and cooking are a little bit too old. (good mainly only for the soluble fiber)
    Flaxseed should not be soaked, contact with water brings together the two elements in flaxseed which produce cianide.
    And should not be cooked, it destroys a large percent of the great vitamins and essential fatty acids.
    FEED IT FRESH GROUND in order to preserve all the vitamins and fatty acids. Only ONE simple rule, feed in small doses and you have no problems.
    Or, if you are still worried, feed flaxseed oil. (only cold-pressed) BEST OIL FOR HORSES, period. (most Omega-3 of any oil -which most horses really need. 🙂

  34. I was told by my farrier to feed our 14-year-old reining mare flax seed oil to help with her coat and hooves. She has foundered in the past, so I was skeptical. After discussing with our vet he agreed that it would be safe for her. We were using it religiously twice a day. She had a very good show season with my 11-year-old son. I’m not sure why, but we haven’t been giving it to her for the past couple of months and she seems to be stiff and sore and the trainer suggested having her hocks injected. We’re starting her back on it right now to see if we see any significant improvement before we have her hocks injected. I would prefer NOT to get started on that if the flax seed oil will do the job. It is much less expensive and I would imagine better for her overall health. Puritan’s Pride sells it online and is always running a special such as buy 1 get 2 free. She goes back into hard training in about 4 weeks. We’ll see if the flax seed oil does the trick. I’ll report back with the results.

  35. The old adage about needing to boil flaxseed appears to not only be outdated, but actually causes what it purported to prevent – actually bringing the toxic elements together. Flaxseed can be fed whole, horsepeople have been doing it for years. You can also buy it already ground and stabilized which gives you a longer shelf life. A 1200 lb. horse should need no more than 1/2 c. PER DAY.

  36. Q: re the last posting from Karen J–what is your background/research for making the statement about not needing to process flaxseed? Also, if fed whole, is there a possibility that pastures can become infested with the plant itself–some references indicate that the seed can pass through the digestive tract intact. Personal experience shows that unprocessed oats will pass through the digestive tract and germinate in manure piles.

  37. Boiling flaxseed is actually dangerous. It is true that there are two chemical components of cyanine in whole flax seed but they are in separate parts of the seed. When you boil the seeds, the water makes the two components come together and actually creates the toxic gas. Boiling also destroys the fatty acids which is why you feed the flax!

    Also, if you are going to grind the dry seeds yourself, you will have to grind them fresh for each feeding because prolonged exposure to oxygen, heat and light degrades the nutrients in the seed. If you purchase commercially ground seed (at a grocery store or feed store) there will be a stabilizer in the ground seed so that it doesn’t lose its potency. Without the stabilizer, ground flax goes rancid very quickly so if you grind it yourself, you will need to feed it right away and thoroughly clean out your grinding materials.

    There is no problem with feeding whole flaxseed. I can’t say anything for what happens when the seeds freeze, but when you feed them at a normal temperature, the outer shell of the seeds actually form a coating in the digestive tract that keeps the gut moving effectively. You will most likely see some seeds in your horse’s manure if you feed whole seeds. Nutrients are still extracted from the seeds even tho some hulls are cast aside.

    Happy feeding!

  38. I have been feeding ground flax seed meal to my horse for years. I buy Bob’s Red Mill brand,(which I know is human grade but it has never caused any problems and my horse likes it and the benefits are visible), they have an organic option as well. But I recently purchased Omega Horseshine which can be purchased at Tractor Supply for a reasonable price and the first ingredient is flaxseed meal and they have a stabilizer in the supplement. I have read countless positive testimonials regarding this product and it offers many benefits for horses. So, if anyone is unsure about feeding flaxseed meal only then maybe you should try the Omega Horseshine, not to mention it was Horse Journal’s product of the year and best in nutrition.

  39. I sure wish people would educate themselves on different feeds and preparations. Flax seed is safest fed whole and not soaked or boiled; and please, folks, please…just because grampas horses didn’t die doesn’t mean they weren’t slowly poisoned. It also doesn’t mean that was the correct way, or how it should still be done. Wheat bran is NOT good for horses, and is actually quite toxic, as is corn. Doesn’t matter if the author of an article writes about how great something is or how to feed it, research it and learn. Ask an expert about the good and the bad, not take the word of some writer just because it’s in an equine mag or journal. That doesn’t make them an educated equine resource, it makes them exactly what they are, a reporter.

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