Spring is, in general, a very excitable time for horses...temperatures in their comfort zone, something fresh to eat growing, and mares coming into season. You can expect any horse to very fresh during this time before hotter weather settles in.
It can make them founder also if too much is eaten. You need to be careful letting them out on grass for too long. Because for 3-4mnths your horse hasn't eaten that and you will need to gradually wean him/her on it.
As far as making them "mad" "fresh", yeah, but I think a cold snap or a brisk wind can make them feel frisky too. The above is just a warning. Posted via Mobile Device
The first grass of Spring does have an extremely high concentration of sugar, as I recall it is fructose. A lot of horses are susceptible to foundering/laminitis turned out on the new Spring grass because of the sugar concentrate. To prevent grass founder a horse should only be allowed a short time in turn out so as to not be able an eat an overly excessive amount of the new grass. The amount of time on turn out can gradually be increased as the horse's digestive system gets accustomed to the new green grass.
I agree with what PaintHorseMares says also. Spring is an excitable time for our horses.
You shouldnt really have much sprin grass atm Lola were only starting and its bare minimum.
If your horse is out 24-7 then they should make the transition easier as they are nibbling at the grass and the sugar is gradually introduced to there system. Its horse who stay in all winter and go out in the middle of the growth that go loopy.
My ponies just get a bit more umph in them they can be very reluctant to come in though off it.