What Foods & Plants are Poisonous to Horses?

If you’re an equestrian, then you know that owning a horse isn’t like having a pet . . . it’s more like having a companion whose well-being, comfort and joy are very important to you. Making sure that the foods you give your horse aren’t harmful to it should be one of your most important priorities.

There are plenty of horse treats available on the market for spoiling your horse, and most human foods are safe to feed horses in small amounts. But a small number of foods and plants are dangerous for horses, and some are downright poisonous and could make your horse very sick (or even kill them) if eaten in large amounts.

Here’s a list of different foods and plants that can be harmful, dangerous or poisonous to a horse if they eat them. While your horses aren’t likely to accidentally come across these very often, any foods that cause colic in horses (or lead to death) should be something that an equestrian should be at least familiar with.

A List of Human Foods & Plants That Are Harmful or Poisonous to Horses

1. Caffeine

While tiny amounts of caffeine probably won’t hurt your horse, you should still avoid giving him any foods that have caffeine in it. It’s rare, but it could potentially cause irregular heartbeat problems to arise.

2. Avocado

Avocados can be poisonous to horses if they eat them. Both the meat of the vegetable, the skin and the leaves of it can be harmful for horses.

3. Fruits with Stones (or Pits)

Any kind of a fruit that has a “stone” in it (or pit), like whole peaches, avocados, and cherries, can be dangerous for a horse, because they could choke on the pit.

4. Cauliflower, Cabbage, Broccoli

If your horse consumes any of these three things in excess, then it can lead to very bad gas and colic problems that could hurt them. Better to avoid these three vegetables!

5. Bran Products

Feeding your horse bran can possible cause some digestive problems and diarrhea.

6. Potatoes

It’s best to avoid giving potatoes to your horse (although we know some horse owners who occasionally feed them the potato chips as a snack). This big problem arises if the potatoes are moldy or too “green,” because it can make your horse get toxicosis (or choke on a tough, unripe potato).

7. Rhubarb

If your horse eats rhubarb, it can be a very bad thing. Rhubarb is known to make horses very sick, and cause injuries to their urinary tract and digestive systems. This can result in kidney failure. One of the reasons why rhubarb is so poisonous to horses is that it contains calcium oxalates, which horses don’t tolerate well.

8. Meat Products

Yes, we have seen some horses take a bit of a cheeseburger, hotdog or chicken nugget and be just fine. And on farms, horses can sometimes be seen bending down and eating a baby chick (gross and sad, yes, but a reality nonetheless).

Still, meat products should not be offered to horses, who are naturally herbivores and not carnivores. The digestive system of a horse is simply not evolved to have any kind of meat processed through it.

9. Bread, Rolls, Donuts, Etc.

While bread products are not poisonous to horses, they can get stuck in their throats and possible cause them to choke and die, which is a hazard. It’s best to just not feed a horse any kind of bread!

10. Dairy Products

Just like humans, horses can also be lactose intolerant. Milk isn’t outright “poisonous” to horses, but there’s always the possibility that it could cause digestion issues. Like other animals, horses shouldn’t drink milk once they are grown up. It might be nutritious and important for babies, but not for adults.

11. Chocolate

Chocolate can be poisonous to dogs, and horses also should not eat chocolate. Not only does chocolate have caffeine in it (see above), it also contains something called theobromine, which is poisonous to horses in large amounts. It can cause internal bleeding, metabolic derangement, seizures and colic (yeah, every one of those things are situations that you definitely want to avoid).

12. Onions and Garlic

Vegetables like garlic and onions are members of the family of plants called the “allium” family. (The allium family of plants also includes chives, shallots and leeks.) These plants should generally be avoided by horses because they can damage red blood cells and lead to sickness.

13. Tomatoes

Humans might find tomatoes to be tasty and nutritious, but not so for horses. If a horse eats tomatoes, it can cause an increased heart rate, constipation and other dangers.