feeding my new horse

Question
I just got a 16 y.o. gelding a few days ago.I wormed him and have been feeding him oats and coastal hay. He is beginning to have diarehia. Is there a problem and do i need to change anything?

Answer
Hi Donna,

Thank you for your question and congratulations on your new horse.  The diarrhea that your horse is experiencing could be the result of a few different issues and it make take a few days to figure out the source.

Horses can develop diarrhea from the deworming itself, either the result of the death of a heavy parasite load or from the effect of the anthelmintic drugs on the digestive tract itself.  If the worming is the source of the diarrhea, then it should pass in a few days and the manure return to normal.  

Oats are a cereal grain that are relatively high in starch, to which your horse could react to by developing diarrhea.  Too much cereal grain per feeding could induce the diarrhea, you should never feed more than 1kg per feeding for an average size horse.  Or some horses simply can not tolerate high starch diets, in which case you would need to look for a complete feed that is fat and fiber based, and uses no added starch.

Changes in a horse's diet should be done over a course of 7-10 days, so it is possible that your horse has developed diarrhea in response to a sudden change in diet.  If this is the case, the diarrhea would resolve itself once the horse's digestive tract has adjusted to the change in the ration...in about 7-10 days.

In order to figure out which of these (or other) situations has caused the diarrhea, I would suggest that you remove grain from the diet for the next week or so, feed your hay free choice and allow your horse's digestive tract to settle.  This will allow the recovery from the worming and the adjustment of the digestive tract to your new hay.  Then, once your gelding's manure has returned to normal, you can re-introduce the oats or other grain gradually.  If you start your horse on oats again and the diarrhea re-develops then I would strongly urge you to stay away from cereals and go with a high fat/high fiber alternative.  Remember that horses require significant time to adjust to rations high in fat...so if this becomes part of your ration allow yourself a good 14-21 days to work your horse up to the daily recommended feeding rate.  

I hope this is of some help.

Thanks, Corlena