Spring Grass Fever

It's that time again when the grass is causing hyper-sensitivity, excess energy and tight muscles. I spoke to vet Tim Montgomery from The Vet Centre in Pukekohe to get his advice. He warns that it's not just a behavioural problem but also they are seeing lots of cases of Laminitis, even in hacks.

Tim's advice:

  1. Limit the amount of grass and supplement with hay.
  2. Supplement feed with Calcium, Magnesium and Salt.
  3. If symptoms persist run a blood test to test electrolytes.

Why do they get Spring fever

To put it simply , grass goes into shock as we are having cold nights followed by warm days. It produces high levels of Oligofructose and Potassium and the level of Calcium, Magnesium and Salt drops. Emma Kay has written a brilliant explanation which explains it more in depth and also has a lot of helpful tips.


I have a property that causes lots of unhelpful grass issues and I have my horses constantly on 2 Tb of Salt , the Duwell Toxin binder and 40-60 mls of the liquid Magnesium. If I have something really spooky and "seeing ghosts" i put them on the Compete and Grow which has the Calcium as well.

Signs to looks out for

  1. Contact suddenly gets hard and horses lean
  2. Horse becomes stiff over the back and hind-quarters, can change leads behind
  3. Horses become tense and less able to concentrate
  4. Horses become spooky at things on the ground as it affects their vision
  5. Horses may start stopping at jumps as vision is affected
  6. Horses may start bucking