The Interesting Thing About Winter Laminitis

You would think that as grass growth slows down, laminitis prone horses and ponies would be less likely to tip over into laminitis.

However this is not the case and autumn/winter grass is just as likely to be problematic for those susceptible horses and ponies as grass in spring.

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For many years we have observed that any time grass is GREEN, whether short or long, it poses a danger for EMS or laminitis prone equines. Even horses with no outward signs may be susceptible. And low grade (sub-clinical – just below the surface) laminitis can easily go unrecognised.

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Here in New Zealand and lower regions of Australia, where winter temperatures are nowhere near as cold as in parts of UK, Northern Europe, Scandinavia, North America and other regions where horses are living in snow and ice for months at a time, plenty of horses succumb to laminitis even though grass growth has slowed right down.

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The healthy equine hoof is well adapted to very cold conditions to ensure it doesn’t freeze when exposed to icy conditions for extended periods. However in the case of our domestic horses, if their metabolism is compromised by EMS, Insulin Resistance or any kind of Insulin Dysregulation, blood supply to the internal structures of the hoof becomes subject to abnormal constriction which can precipitate an episode of laminitis. It is therefore prudent to feed these horses and ponies forage and feed which is least likely to aggravate insulin levels and which will serve the purpose of ultimately reversing the syndrome.

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It is recognised that Lucerne/alfalfa cannot be fed to ‘some’ horses with laminitis but ‘nobody knows why’.
The clues lie in the similarity of its nutrient profile with winter grass. Hence, for the following reasons we don’t recommend feeding it to ANY equine who is prone to or has laminitis despite it’s relatively low sugar content.

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There are two significant common denominators between winter grass and legumes like lucerne/alfalfa or clover. They are simultaneously excessive in both Potassium and Nitrogen/Crude Protein. When one is high the other is inevitably also high.

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Out of nine forage analyses CHH conducted from late Autumn/winter pastures that caused laminitis all were excessive in potassium (2.3-4.1%) and nitrogen/crude protein (16.8-36.3%) and yet all were well below 10% in sugars.

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Both potassium and amino acids are known ‘insulin secretagogues’ (substances which promote secretion of insulin).

Potassium is usually ‘written off’ as not a problem – however as with all aspects of physiology it cannot be separated out and excluded especially when combined with the effect of amino acids (within Crude Protein) on insulin secretion. Studies have shown that horses with EMS had a “9-fold greater insulinemic response to the consumption of a high protein meal compared to controls”. In a nutshell this is because amino acids which are in excess of requirements can be converted to glucose and thereby contribute to excess insulin production.

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Take Home Message:

EMS and laminitis prone individuals, for the purpose of prevention and normalising their errant metabolism, are best fed ‘Low Nutrient Density’ forage, ie grass hay that is LOW in potassium, CP and sugars. Most hays will need to be soaked to achieve low levels of these aspects.

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Then be very mindful about what hardfeeds consist of. To address EMS, in our experience it is best to provide ‘non-calorie’ nutrients ie the minimal quantity of feed that the horses will consume their BROAD SPECTRUM minerals & vitamins. We emphasis the broad spectrum because all minerals (and other nutrients) require the presence of specific co-factors for them to be effective. They do not work on their own, rather as a 'team'!

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CHH have consistently observed the best results since following these principles over the years.

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"Netta" the pony in the video illustrates the point - she became laminitic on winter grass but got no better when taken off that grass and put onto a very high lucerne diet. It was after removing all the lucerne and switching to plain grass hay that she turned the corner and really improved.

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References:

1. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition Asghar Rastegar. Chapter 195 Serum Potassium
 

2. Forage crude protein concentration affects horses’ insulin response - Sara Muhonen Feb 17, 2018
 

3. A high protein meal affects plasma insulin concentrations and amino acid metabolism in horses with equine metabolic syndrome C M M Loos 1, S C Dorsch 1, S E Elzinga 2, T Brewster-Barnes 1, E S Vanzant 1, A A Adams 3, K L Urschel 4