If its Autumn or Spring, the risk is highest but certain grasses, supplements and feeds can affect some horses all year long.
A ‘Grass affected horse’ is one where one or multiple aspects of their diet are adversely affecting their health and behaviour. This usually originates from the forage (grass) but can be further exacerbated by the addition of other potassium rich feeds to their diet.
The fastest way to create a ‘Grass Affected’ horse is to graze them on dairy pasture or other pasture that has been fertilized with potash, super-phosphate, DAP, Urea, NPK etc. This is enough to create a ‘Grass Affected’ horse within a few weeks. In fact we know of horses who have been seriously affected within a few hours on such pasture.
Some people find this out when they go to a show or a trek and have to leave their horse on unsuitable grass overnight; by morning they have a fire breathing, foot stomping, spaced out lunatic, which hopefully they have the sense not to ride!
Others may find this out when they sell their ‘normal’ horse to someone who has unsuitable pasture and they get a call a few weeks later to say the horse ‘must have been sedated’ because he is now not the same horse they bought!
Giving any susceptible horse a hard feed consisting of lucerne, molasses or soy based products, adding a sprinkling of kelp, throwing in a few potassium-rich herbs and relying on a mineral lick for salt (salt deficiency is one of the major causes) and minerals is another sure-fire way to get them into the ‘Grass Affected’ category. Put the two together (‘unsuitable’ grass plus ‘unsuitable’ feed) and you have a horse on rocket fuel that is likely to hurt somebody.
How quickly any individual horse succumbs depends on how their particular system copes with these imbalances. This is why taking the horse off grass temporarily helps so much, because it immediately lowers potassium intake down to a more suitable level and thereby gives their whole system a rest.
There are, of course, many variables contributing to whether your horse becomes ‘Grass Affected’ or not. Be aware. Get familiar with all the signs by downloading and printing off one of the ‘Horse Symptom Checklist’ and ticking the boxes. This will give you the ‘heads up’ so you can make some diet adjustments. An ounce of prevention is worth a ton of cure.
Click here to read our article – Symptom Checklist – What’s Wrong With My Horse?