Q: It is well known that corn oil is not as good for people as are other cooking oils, but is the same true for our horses? My aging Thoroughbred-cross gelding receives a quarter cup a day. I mix the corn oil with a powdered joint supplement that I add to his senior feed. If I don’t add corn oil as a binder, the granular powder is left at the bottom of the pan. He can also use the added fat. How safe is corn oil for our horses? Liz Blackburn; Montrose, Colorado

A: Corn oil is safe, especially in that amount. Although some studies suggest that because corn oil has a higher ratio of omega-6 fatty acids to omega-3 fatty acids, it may increase the risk of cancer and heart disease in people, other research contradicts these findings.
At any rate, concerns about omega-6 fatty acids are vastly overrated for horses, especially when you consider that they normally get only 3 percent fat in their daily ration. By comparison, the average American consumes a diet composed of more than 10 percent fat, so a person’s total intake is much higher than a horse’s would be.

The quarter cup of corn oil you are giving your horse daily is a very minor addition to his diet. If you are concerned, you could just as easily use soybean oil, also known as vegetable oil. In my experience horses do not like canola oil or those that are higher in omega-3 fatty acids, such as flax or fish oil.

Sarah Ralston, VMD, PhD, DACVN
Rutgers University
New Brunswick, New Jersey