Can Horses Eat Onions?
I think my favorite smell in the whole world is onions and garlic, sautéing in butter.
The other day, I was cooking up a sweet onion and probably nine cloves of garlic as a base for a sauce.
My mind drifted away to riding my horse, which I hadn’t been able to do for a few days.
The glorious smell coming up from the saucepan filled my nostrils, and the question hit me: are onions an appropriate snack for my horse?
The answer to this question is, no, horses cannot eat onions. Onions and other members of the Allium genus, like leeks and scallions, are toxic to horses. Even those little wild onions that grow everywhere can potentially make your horse very ill.
In this article, we will explore why horses cannot eat onions or other alliums, what plants fall under the allium umbrella, and signs of allium toxicosis in horses.
As horse owners, we should all be as vigilant as possible in keeping our horses safe and healthy.
Let’s get into it!
Why are onions bad for horses?
Onions and other plants of the Allium genus are toxic to horses because of the sulfides they contain, particularly n-propyl disulfide.
Here’s what can happen when horses consume these sulfides: the sulfides damage red blood cells, and the damaged red blood cells form into “Heinz bodies”.
When the horse’s body removes these Heinz bodies from circulation in the bloodstream, a condition called Heinz hemolytic anemia occurs.
Some of the symptoms of anemia in horses are:
Increased heart rate
Staggering
Dark or bloody urine
Abortion in female horses
What are some signs of onion toxicosis in horses?
Anemia can be a sign of onion toxicosis in horses, but some other possible dangerous symptoms your horse could experience after eating onions or other alliums are:
Malodorous, onion-scented breath
Weak pulse
Problems with mucus membranes
What do you do if your horse eats onions?
If you suspect (or know for a fact) that your horse has eaten onions, you should take them to your veterinarian.
Your vet will do blood work on your horse to figure out exactly what’s going on.
They may even want to run other tests to rule out any other problems or discover any comorbidities.
Then you’re going to need to figure out where they got the onion from, especially if you have other horses who could be at risk of the same toxicosis.
The most likely scenarios are wild onions on your horse’s grazing land or your horse getting into kitchen scraps containing bits of onion or onion skins.
After you find the source, you need to mitigate risks for your horse.
Pull any wild onions you see growing and make sure that your horse doesn’t have access to any scraps of onion or onion skin/peel.
Can horses eat wild onions?
No, horses cannot eat wild onions.
If you have any of these growing where your horse grazes, try to pull up as many as possible to minimize the risk of your horse getting sick.
Horses do not instinctively know which foods are toxic to them, so do not assume a hungry horse will skip over a patch of fresh wild onions.
Plus, if you pull up the wild onions from your field, you can use them in your cooking.
They have a distinctive smell and taste, but I’ve found them to be nice diced up fine in a soup.
Can horses eat leeks?
No, horses cannot eat leeks.
Can horses eat scallions?
No, horses cannot eat scallions.
Can horses eat shallots?
No, horses cannot eat shallots.
Can horses eat sweet onions?
No, horses cannot eat sweet onions.
Can horses eat green/spring onions?
No, horses cannot eat green or spring onions.
Can horses eat onion skin?
No, horses cannot eat onion skin. While it contains less of the toxic compounds, n-propyl disulfide, and other sulfides, than the bulb of the onion, onion skin is still dangerous to your horse.
Can horses eat any type of onion?
No, horses cannot eat any type of onion.
All types of onions are bad for horses: red onions, yellow onions, white onions, pearl onions, Vidalia onions.
If it’s got “onion” in the name, your horse cannot eat it without possibly life-threatening consequences.
Can horses eat garlic?
This one is a little more complicated, as horses can have small amounts of garlic as a supplement.
The active compound in garlic is called allicin.
Allicin (garlic) can help horses with many ailments; helping their respiratory systems function better, boosting their immune systems, and keeping away aggravating flies (and obviously, any local vampires as well).
Garlic also has a ton of the minerals sulfur and selenium in it.
Arguably, the best way to give your horse a dose of this healthy allicin is with garlic oil.
Garlic oil is highly concentrated and only a small amount is needed.
A bit of garlic oil is often mixed in when honey is given to horses as a treat, and most horses enjoy the taste.
Giving your horse fresh garlic won’t afford them the benefits you’re hoping for unless you crush or cut the garlic beforehand.
Garlic doesn’t release, or activate, allicin until it is “assaulted” in some way.
Horses are sometimes given dried garlic, but that isn’t the best method, as too high of a temperature destroys allicin.
Be careful how much garlic you are supplementing your horse’s diet with.
If you give your horse too much garlic, it can cause the same toxicosis as onions and other alliums, possibly resulting in Heinz hemolytic anemia.
You don’t want to feed your horse more than an ounce or two of garlic per day, depending on their size.
After reading all this, you can probably identify most members of the allium family.
Now, there are hundreds of different types of onions, so this list is not by any means exhaustive, but allium plants have a similar look and smell, so you should be able to classify any you come across.
Keep these plants away from your horses as best you can and take your horse to see your veterinarian as soon as possible if they have ingested any onions or more than a small amount of garlic.