Zinc Deficiency in Horses

“A healthy outside starts from the inside.” ~Robert Urich

It seems we horse owners will go to great lengths to remedy our horse’s hoof problems, and often to no avail.  Oils, creams, supplements–we’ll try it all!   Since I began my quest to learn about equine (and then, human) nutrition several years ago, I’ve learned there is a commonly missed, but fantastically simple answer to many of our problems (equine and human, alike)–nutrition!  If there’s an ongoing symptom on the outside, something’s likely missing on the inside.   In the case of hoof problems–poor hoof quality, brittle, flaking hoof walls, thrush, etc., despite good hoof care–it is most likely due to a zinc deficiency.

According to the National Research Council’s (NRC) nutrient requirements for horses, a mature horse weighing 500 kg (1100 lbs) needs a maintenance amount of 400 mg of zinc per day.  Those amounts would increase as work loads increased for the horse.  Of course zinc is just one of several trace minerals needed by the horse and it’s imporant to ensure that all trace mineral needs are being met.  Copper is another trace that is often deficient in equine diets.  If you supplemented zinc alone, without paying attention to copper or the other traces, your problems would still likely exist.  But for the purpose of this post–I’ll focus on zinc.

I routinely get my hay and pasture analyzed, and every time, they’ve shown to be short on zinc (as well as other important equine minerals.)  Talking with other horse owners who get their forage tested in order to balance their horse’s diet, zinc deficiencies are extremely common.

Added to the common problem of too little zinc is the likelihood of too much iron, another trace mineral, in the diet.  (I know, I said I would focus on zinc–but I can’t mention zinc deficiencies without addressing iron!) Too much iron blocks the absorbtion of zinc and can create a deficiency problem as well.  The NRC recommends an iron: copper: zinc ratio of 4: 1: 3.  The iron levels in my forage are usually so high that I have  to add quite a bit of copper and zinc in order to correct the ratio.   And since iron is in just about anything the horse consumes (water, grass, hay, feeds, most supplements) this is a bigger problem than most people would believe.

Some signs of a zinc deficiency in horses include:

  • poor coat
  • mouth ulcers
  • flaky skin
  • poor hoof quality
  • poor fertility
  • low immunity
  • predisposition to skin infections
  • ongoing thrush

So what to do if your horse does indeed have a zinc deficiency?  Just buy a commercial hoof/ coat supplement and the problem’s fixed, right?  Wrong–well, in many cases!  Most of the commercial hoof and/or coat supplements (as well as some commercial feeds) out there contain a good deal of zinc, but I’ve never found one that had enough to cover my horses’ deficiencies.  And believe me, I’ve looked!  Plus, nearly every one I’ve seen also contains IRON–once again throwing the ratio out-of-whack!  I’m not sure why, but it seems that many of these nutritional supplement companies just don’t get it!

So what is the best way to supplement a diet deficient in zinc, or any other mineral, for that matter?  Simple–just feed the individual minerals themselves–in the correct amounts and ratio, of course.  I order Poly Zinc from a company called Horsetech.  There is also a great supplement available called California Trace that has much higher levels of copper and zinc (and no iron to inhibit absorbtion) than other supplements I’ve seen.  It can be ordered online.  I’ve not used it personally, but heard rave reviews about it.  If you don’t want to mess with getting your forage tested  or feeding individual minerals–it may be the way to go.

When I learned how to balance my horses’ diets and started supplementing the individual minerals–including zinc– a few years ago, I took some before and after photos.  Here are a few.  You can see Bob’s coat darkened and lost the washed-out appearance (and no, he’s not in foal!) and Bo, who had terrible feet, showed considerable improvement as well.

Bob Before

Bob After

Bo Before

Bo After



Hi! My name is Casie Bazay. I'm a mom, a freelance writer, and a certified equine acupressure practitioner.

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5 Responses

  1. Minnie says:

    Hi there – I interesting story … have a mare with two cracked hooves – she has been left to get very fat so I suspect diet has a role to play I have ordered some zinc but was wondering how much I should give her – she is a full TB – 7 yo and approx. 15.2hh – much appreciated!

    • then5925 says:

      Hi Minnie–unfortunately, that’s not an easy question to answer unless you know how much zinc she’s currently getting in her diet. Getting a hay or pasture analysis is the easiest way to find out. Many horse’s diets are deficient in zinc (and copper), but I unless you know how much, you’re really just taking a guess at how much to supplement. The trace minerals also need to be fed in the correct ratios or else you’re really not going to see a difference. If you don’t want to get a forage analysis, the next best thing would be to find a regional analysis and go from there OR buy a good trace mineral supplement like California Trace with balanced minerals and NO iron.


  2. Billy says:

    Do you know of any research concerning zinc/copper deficiency and ongoing thrush? Thanks.

    • Casie says:

      Hi Billy–no, unfortunately I don’t know of any research on this, but it would certainly be interesting to see some. I have heard quite a few personal stories of thrush clearing up with balanced trace minerals though.

  1. January 7, 2013

    […] important factor is diet–so that should be evaluated as well.  A copper and/or zinc deficiency and diets high in carbohydrates (too much grain, alfalfa, rich grass, etc.) are also linked with […]

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