There is a silent danger lurking in your pasture

Spring Grass might look super healthy, but it can be a silent killer for horses.

I always look forward to spring.  Usually, by February I’m thinking I just can’t take any more mud and rain.  Here in the Pacific Northwest we usually don’t get a lot of snow and so spring is a promise the muddy slop will soon start to dry, and the tulips will bloom.  As the weather warms, the pastures also start to firm up and turn green.    

I’m pretty sure our horses are just as happy to get out of the dry lots to get a taste of that lush green spring grass.  But spring grass has been tied to increased risk of laminitis, also known as founder. One theory is that rapidly growing grass is packed with fructan (a form of stored sugar) and ingesting too much of that sugar causes the hindgut to experience an overgrowth of bacteria.  That bacteria then releases endotoxins that enter the bloodstream and cause inflammation in the hoof capsule resulting in laminitis.  

Laminitis, sometimes called founder, is the inflammation of the laminae within the horse’s hoof.  The laminae attach the hoof wall to the coffin bone.  Inflammation damages this delicate structure and the hoof wall can detach from the coffin bone.  In severe cases, the coffin bone rotates right through the sole of the horse’s hoof.  The resulting infections and severe lameness can mean the death of an otherwise healthy horse. 

The above graphic shows the three developing stages of Laminitis severity. Sourced via: http://www.valleyveterinarygroup.com/equine/laminitis/index.html (2013)

 In recent years, some have suggested that it’s not actually the sugar content of the grass that is the culprit, but the magnesium content.  Just as spring grass has been accused of causing laminitis in horses due to high sugar contents, it’s also blamed for horses becoming spooky and hyper.  The thought was that lush grass had a high energy content and was the culprit of these symptoms.  But these symptoms of ultra-awareness and spookiness, along with laminitis may be a magnesium deficiency.  This theory has little research behind it and so us horse owners are left wondering what the danger really is.  Is it high sugar intake or is it an imbalance in magnesium?

The good news is that Magnesium does help prevent laminitis in horses when on spring grass.  I’ve personally used a magnesium supplement for years and noticed that my horses no longer get the stretched out white line in the toe I’d often seen during spring at trim time.  This makes Magnesium my number 1 recommendation as a supplement for any horse with access to spring grass. 

Magnesium Oxide is a common supplement for horses and is easily found anywhere you find horse supplements.  A study conducted at Ohio State University identified that horses need approximately 13 milligrams of Magnesium per kilogram of body weight.  But, it’s important to note that horses only use about 70% of the magnesium available and magnesium is lost in large quantities when a horse sweats. 

Product recommendation: If you are thinking of feeding Magnesium to your horses, there are a ton of options out there. Recently I’ve been using Uckele Magnesium Oxide. This is a very low-cost option but it’s a dusty powder. I recommend wetting grain/feed with water so the horses don’t breathe it in or leave it at the bottom of the feed bucket.

If you are looking for an easier pelleted for, I recommend Med Vet Magnesium 5000. I used this for years when I just had one or two horses on Magnesium. It’s easy to feed and you won’t have power all over everything.