The Effects of Seasonal Change after a Drought

Les Rees

It's been a long time since we had any rain in the Northern Rivers and the land has dried out massively causing trees and shrubs to flower earlier than normal in a last ditch attempt to create seed for the rainy season to nourish them. Most people I talk to are looking forward to the long awaited rain to arrive to activate the renewal of the lifecycle and invigorate our senses and awareness of the wonders within the natural world. However, as with all things this can have as many negatives as positives for our horses.

Having sensitive digestive function, equines are susceptible to developing a range of problems when they have access to rich grasses during high growth periods, especially after having a diet of dried grasses during a drought. Grass reacts very quickly to rain taking advantage of the wet conditions using photosynthesis to convert sunlight into sugars from carbon dioxide in the form of non-structural carbohydrates (NSCs) needed to promote a new growth of rich green shoots. The problem for horses is that their digestive system can't cope with the high levels of NSCs, and like us they are attracted to rich foods which can cause life threatening conditions.

When equines gorge themselves on the lush grass, enzymes in the digestive tract convert starch and sugars into simple sugars to enable the body to absorb them. This causes a surge in blood glucose which initiates the release of insulin into the bloodstream enabling the uptake of glucose into the tissues. Problems occur when fluctuations of glucose and subsequent insulin concentrations overload the balance of the system making it less sensitive resulting in an over-supply of insulin to control the blood glucose levels, and this can be a contributor to insulin resistance.

Furthermore, research has shown that elevated glucose levels can trigger laminitic conditions. Laminitis is an extremely painful condition of the feet where the laminae surrounding the pedal bone in the hoof becomes so weakened that they can no longer hold it in place. In advanced cases the bone rotates causing even more painful pressure within the hoof. Due to the long and painful recovery period, horses are often put down at this stage, so it pays to be aware of the possibilities before it becomes too bad to deal with!

Grasses can also contain high levels of fructose molecules known as fructans which are a non-structural carbohydrate and un-digestible. In order for the horse to absorb them, they have to be fermented by microbial activity in the large intestine and in large quantities can cause a similar response to an overload of NSCs as it also initiates increased insulin levels and therefore another contributor to insulin resistance and possible laminitic activity.

After long periods of drought a sudden flush of new grass can also cause colic. Horses have highly sensitive digestive systems and fructans are not good for the bacteria in the gut. High fructan levels kill the good bacteria and cause acidity levels to rise and the subsequent release of harmful pathogens resulting in colic.

I often wonder how horses have managed to survive in domesticity when I consider the factors involved in keeping them in good condition, given their sensitivity to lush grass and a myriad of other possibilities that can affect their health and wellbeing. We all need to be aware of the consequences of allowing our horses to eat the lush grass that will start to spring any time now. If in doubt, restrict grazing time and assess their diet. There are herbs that can be very helpful for horses. Used as preventatives they can be very useful in protecting them from seasonal disorders as well as being very powerful to promote healing.

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