Grass Affection- By Michelle Sefton

Grass Affection- By Michelle Sefton


Grass Affection- By Michelle Sefton

I am writing this article as our autumn weather is a lot like our spring weather this season. With warmth and humidity during the day and cool at night, though still humid. With the added showers of rain it is prime time for the fungal spores to continue growing on the ground and on the grasses. Also with this combination of weather comes high sugar and high potassium levels in the grass, as we have seen most of summer since spring, with our unpredictable weather changes.


Grass affection has been a hot topic since spring and still is. Not only are people experiencing behavioural changes with their horses/ponies that come with the grasses high in fungal spores, high in sugar and high in potassium but also staggers from rye grass and paspalum. Grass affection signs if not addressed with changes in the diet can lead to serious issues such as staggers with the build up of toxins however, staggers can be sudden onset and if the horse/pony is not removed off grass immediately to somewhere safe they can easily lose balance, fall, get injured or worst case scenario end up with such injuries there is only one kind thing we can do for them, have they not passed on already.


Signs of grass affection and grass staggers


  • Skin sensitivity
  • Spooky
  • Head flicking
  • Anxious
  • Nervous
  • Aggression
  • Food sensitivities
  • Out of the normal behaviour on the ground and ridden
  • Biting
  • Rearing
  • Bucking
  • Enlarged glands
  • Ataxia, back end wobbling, this is seen with staggers
  • Loss of coordination and or balance


If you see any of the above behaviours remove your horse/pony off grass immediately and put them in a safe yard, stable or raceway away from any and all grass. The toxins they are showing at this point are what was ingested 24hrs to 7 days prior. It will take a good 10 to 14days for all toxins to work out of their system. They need to stay off grass for 14days then be slowly reintroduced to grass. Bare in mind when doing this, as a guideline, the sugars in the grass is highest between 10am and 2pm. Also horses graze more at night than during the day.


While yarded they will need to have constant access to a fibre source. If feeding hay make sure it is well soaked to remove all the sugars, if you are feeding baylage, remember to slowly introduce it as to not give your horse/pony a protein overload. Have free access to water also. Hard feed twice a day.


With hard feed please ensure you have read and noted what is in every element of your horse/pony hard feed. When grass affection occurs or with staggers it is the excess of potassium and sugar in the grass and toxins from fungal spores with rye grass and paspalum that cause their bodies to become out of balance and toxic, (staggers will show the more neurological signs, where as grass affection causes behavioural changes). If you are feeding high sugar, high potassium diets and are not countering this with more sodium and fibre or hard feed less in sugar, the scales will tip more.


As a preventative measure I always recommend feeding salt daily in feed at 10gm per 100kg bodyweight, this helps balance out the sodium/potassium levels in the grass, so bare in mind what excess potassium and sodium they get in their hard feed and additives that will also need to be balanced out so your horse is on a balanced diet. Salt also encourages water intake which will help flush any toxins out of the system. A horse’s body does not register when they are low in sodium so they will never get all the sodium they need from a salt lick. Also making sure your horse is on a balanced diet with a good vitamin and mineral mix that suits your horse and the grasses he/she is on is paramount, Farmalogic Equine NZ do a great range of vitamin and mineral supplements to cater for what your horse’s/ponies needs are and the type of grass that they are on. I also highly recommend Farmalogic Graizeaid if your horse/pony is well known to be affected by the grasses and toxins in this current climate.


NOTE: DO NOT FEED YOUR HORSE IODIZED SALT OR HIMALAYAN SALT. I recommend Ag Salt from your feed store. Horses can become very unwell with too much iodine and iron in their diet.


It is always good to have your horse on something to help gut health, which helps your horse break down toxins to move through the body and exit, as well as being able to absorb the right nutrients they need for optimal health inside and out and to help gut flora. I recommend Dynavyte Microbiome Support, as a pre and prebiotic. If your horse is showing other grass affection signs or signs of ulcers Dynavyte Egusceed is a great product to add.


If anyone has any questions or queries please feel free to contact me through my Facebook page Celtic Stud NZ. I also run an introduction to nutrition clinic, i also do individual nutrition consults.



Michelle Sefton

Celtic Stud NZ

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