Spring is the peak time for grass-associated laminitis in most parts of the world. You can effectively treat or, better yet, prevent it but only if you understand the mechanism.
Photo courtesy of Rebecca Scott
A fat pony is the pasture-child for grass-associated laminitis
First, what it’s not.
There is zero evidence to support the idea that naturally occurring spring pasture laminitis is related to fructan and hind gut fermentation. In fact, all research points to it being caused by high sugar/starch and insulin resistance. Therefore, products like the antibiotic Founderguard or hind gut buffering agents will not be effective.
Animals at risk are ponies, minis, donkeys, full size horses of breeds prone to insulin resistance and pregnant mares. There may be a history of prior episodes of spring grass laminitis in the individual or their relatives.
Although there is a desperate need for well designed studies to look at this in horses, a factor in addition to sugar/starch levels in rapidly growing grasses is their magnesium content. In all species studied, low magnesium status worsens insulin resistance while replacing it results in improvement.
Grasses with magnesium less than 0.2% and potassium 3% or higher can cause magnesium-related problems in ruminants. This is most likely to occur in rapidly growing grasses and made worse by fertilizers containing potassium. If animals cannot be removed from pasture, supplement with 8 to 10 grams of magnesium/day for an average size horse. However, there is no guarantee this will actually be protective.
Limiting grazing time is not always an effective preventative, at least in part because horses given restricted grazing time have been shown to consume grass at 3 times the normal grazing rate. As owners of affected animals can tell you, it does not take a long grazing time for susceptible equines to eat enough to cause laminitis.
The best prevention is to avoid access to spring grass completely. You can still turn out for 2 to 4 hour intervals but with a completely sealed muzzle. Feed only hays known to have a combined sugar (ESC) and starch level of less than 10%. Have minerals analyzed and properly balanced.
If you are dealing with an active case, the above measures still need to be implemented immediately. The key to stopping the process is eliminating the cause. If unsure whether your hay is safe, soak it for 1/2 hour before feeding. A supplement that specifically targets only magnesium, phosphorus, copper, zinc, selenium and iodine will cover the most frequently found mineral deficiencies until a hay analysis can be obtained. Chromium is useful for hays grown on alkaline soils.
Radiographs and a trim to make sure the hoof wall is tightly aligned to the internal structures is very important in both comfort and preventing any further damage.
Pain control is always understandably a major concern but important to realize you can’t control pain without removing the cause (above). NSAIDs like flunixin, phenylbutazone or firocoxib are reasonable for a few days but actually are not very effective for pain relief because features of other types of laminitis such as inflammation, enzyme activation and endotoxemia do not apply to grass induced laminitis.
Once the correct diet and trim are in place, very good results have been obtained by supporting circulation to the feet with Jiaogulan, L-arginine and L-citrulline to fuel production of the vasodilator, nitric oxide.
Preventing spring grass laminitis is certainly preferable to treating it but effective measures are available if you are faced with this challenge.
Eleanor Kellon, VMD