Are Onions Safe for Horses?

Three large onions with light brown skin and green shoots growing from the top, partially covered in soil in a garden bed

Three large onions with light brown skin and green shoots growing from the top, partially covered in soil in a garden bed

No, onions are toxic to horses and should never be fed to them. As a horse owner, you want to ensure that your horse’s diet is nutritious and safe. Although horses may show interest in human food, not all of it is appropriate for their consumption. In this guide, we will discuss onions and why they should be avoided in your horse’s diet.

What are onions for horses?

A close-up of a cross-section of an onion on a blurred backgroundThe presence of N-Propyl Disulfide in onions can harm the red blood cells and cause Heinz’s Hemolytic Anemia, making onions toxic to horses. Horses should avoid consuming onions or any other plants in the Allium genus as they can cause severe health problems and even fatal outcomes, even in small amounts. Moreover, when eaten in large amounts, Thio-sulphate, a substance present in onions, has been linked to Hemolytic Anemia in horses.

Healthy Alternatives to Onions

Freshly harvested onions with roots on a wooden crateThankfully, there are many healthy alternatives that you can use as treats for your horse. Carrots, green beans, turnips, lettuce, sprouts, fennel, peas, beets, parsnips, pumpkins, apples, grapes, strawberries, bananas, pears, raisins, and melons are all great options. These fruits and vegetables are nutritious and do not contain harmful substances that can harm your horse.

Nutritional value of onions

A pile of yellow onions with papery skin on a wooden surfaceOnions are a commonly used vegetable in human cuisine and are known for their pungent flavor and aroma. They are a good source of soluble fiber, vitamins A and C, and contain Quercetin, a flavonoid with anti-inflammatory properties. Onions are not considered a nutritious vegetable for horses since their digestive system is not well-suited to digest onions, and horses do not require vitamin C. Onions are highly toxic to horses and can cause significant health problems even in small quantities.


As a responsible horse owner, it is essential to be aware of the potential dangers of feeding your horse onions. To ensure the health and well-being of your horse, it is essential to avoid feeding onions to them, even in small quantities. For the health and safety of the horse, you should feed fruits and vegetables instead of onions.


Onions are toxic, with both cattle and sheep being particularly susceptible.
Cattle and cats are the most susceptible to onion poisoning, horses and dogs are intermediate, with sheep and goats being the most resistant. Dog breeds such as Akitas and Shibas are especially sensitive to onion poisoning.
These vegetables are absolutely NOT safe for your horse to eat: avocados, Brussels sprouts, cabbage, onions, regular potatoes, tomatoes, and peppers. Avoid feeding horses these vegetables at all costs!

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