deworming my horse

Question
I'VE HAD MY HORSE ONLY ABOUT A MONTH NOW, HE NEEDS TO BE WORMED, BUT THE ONLY THING IS, HE DOESN'T LIKE IT, SO I BOUGHT HIM THE KIND THAT YOU PUT ON THE FEED,(TO GIVE ME TIME TO WORK WITH HIM UNTIL THE NEXT GO AROUND) THE ONLY  PROBLEM WITH THIS IS, HE GRAZES ALL DAY ON GRASS, SO I DON'T GIVE HIM FEED, UNLESS IT'S JUST A LITTLE BIT, BECAUSE HE SEE'S THE NEW MOTHER JENNET (DONKEY) EATING AND GETS JEALOUS, THAT'S WHAT HE WAS ON WHEN I BOUGHT HIM, HE WAS JUST IN A ROUND AREA, NO GRASS, BUT NOW HE'S ON ALL GRASS, WHICH I DIDN'T KNOW I WASN'T SUPPOSED TO DO SO QUICKLY, BUT OTHERS TOLD ME I COULD, THEN LATER FOUND OUT I SHOULDN'T HAVE, BUT ANYWAY, WILL THIS BE O.K. TO DO JUST TO GET HIM DEWORMED? FOR THIS ONE TIME? SO FAR HE'S DONE FINE WITH THE SUDDEN CHANGE FROM FEED TO GRASS, HE'S A 5 YEARS OLD QH. I DID WRONG THE LAST TIME, SO THIS TIME I WANTED TO ASK SOMEONE THAT REALLY KNOWS. CAN YOU PLEASE HELP ME? HE'S MY BABY AND I DON'T WANT TO HURT HIM.THANK YOU, MELISSA

Answer
I dont think that it will hurt him. But if you see any signs of colic call your vet imdetitally. If you are still worried about it just call your vet out and have your vet give him a check up. But the only thing I think you should worry about is colic. I know this isnt much help and I'm sorry. Good Luck!