Bute For Horses, Its Uses, and Its Side Effects

Last Updated on December 8, 2021 by Urska

Can I borrow some bute for horses? This is a commonly heard phrase both at horse shows and at horse barns, particularly show barns.  Bute is as common in the horse world as flowers are in a garden. 

The bute is basically the equine equivalent to Ibuprofen (Advil, Tylenol, etc.) for people.  Bute can help your horse’s aches and pains, fevers, and sore muscles. But, Bute can also be detrimental if not administered properly.

Overuse of bute can cause serious side effects, and it is just as important to be aware of these side effects as it is to be aware of the drug’s benefits.  In this article, I’ll be discussing what bute is, how it works, what it is effective in curing, and what side effects of overuse can be.

What is Bute for Horses?

The Ontario Ministry of Agriculture, Food, and Rural Affairs defines bute as the following:

“Phenylbutazone (Bute) is an analgesic (relieves pain) and anti-inflammatory medication, commonly used for the treatment of lameness in horses. It belongs to a group of medications known as non-steroidal anti-inflammatory drugs (NSAIDS). Phenylbutazone is available in many preparations for horses, including 1-gram tablets, oral paste syringes (containing 6 grams or 12 grams/syringe), an injectable (200 mg/ml in 100-ml vials) and oral powder.”

It is a powder or paste administered to a horse to relieve multiple different categories of pain and discomfort.  But, because of its dangerous side effects, Bute must be prescribed by your vet in order for you to purchase it; it is not a medicine that can be bought “over the counter.”

Bute can be an extremely helpful tool for increasing a horse’s comfort through times of injury or sickness, but it also has detrimental side effects.  

Because bute is so common in the equine industry today,  is important for horse owners to understand when it is appropriate to use bute, and when bute can become a problem for their horses.

What Is Bute For Horses Used For?

Like Ibuprofen, Bute “blocks” a horse’s pain and brings down any inflammation or swelling.  It also acts to lower a horse’s temperature if a horse has a fever.  Because of these characteristics, Bute is the top pick for treating many different conditions in horses. 

Bute is used to treating muscular discomfort in horses, whether this simply be sore muscles from a hard day of work, or musculoskeletal disorders such as arthritis, laminitis, navicular, or degenerative joint disease.

It is also used to treat infections in flesh injuries that can occur from bites, kicks, or unfortunate rolls or run-ins with the fence or a tree.  Bute acts to not only reduce infection, but also to reduce swelling, and therefore pain in affected areas.  

What is Bute Powder for Horses used for?

How Does Bute for Horses Work?

After Bute has been administered either via syringe or via powder, the majority of the drug remains in a horse’s blood.  Damaged or injured areas of a horse’s body automatically have increased blood flow, as the horse’s body is naturally trying to fix the problem.

Because of this, there are also higher quantities of bute being transported to these areas. Bute them blocks chemicals called prostaglandins, which can cause pain.  

While this makes the horse more comfortable, prostaglandins also have important internal functions, which is why it is important to use Bute in low doses, to let the prostaglandins do their jobs. 

The blood eventually flows the bute into a horse’s liver, where it is processed and excreted from the horse’s body within 24 hours of consumption.

In terms of medications, this is a relatively long time for a drug to stay in a horse’s system after administration, and it is a rather long processing time.  This is why it is important not to overuse bute and thereby overwhelm a horse’s liver.

Common Side Effects of Bute

Prostaglandins not only cause pain, but also have an important job of regulating blood flow to a horse’s kidneys, stomach, and gastrointestinal tract.  When these prostaglandins are blocked by the use of bute, they can’t complete these jobs.

Lack of blood flow to the stomach and intestinal tract can increase risk and even cause horses to develop kidney damage or ulcers in their GI tract.  Especially if your horse is prone to either one of these conditions, it is vital to take special care when administering bute to your horse.


For example, my Thoroughbred has been prone to GI ulcers his entire life.  He is on a daily supplement to support GI health, and he gets an ulcer-reducing paste every time his stress levels may increase.  These instances include travel, lack of available turnout, and weather changes.

But, he is also a performance show horse.  After a long day of show, I want to make sure his muscles and joints stay relaxed and comfortable.  Bute is a perfect way to do this, but I have to be extremely careful with the dosage I use. I also need to consider how many days I choose to use it. If not, he runs the risk of his GI ulcers coming back in full strength.


Bute can be a performance horse owner’s best friend! Bute can be a senior horse owner’s best friend! But it can also be both of these horse’s enemies.  It is an extremely useful tool, but it must be used with caution and with the proper knowledge of its side effects.

Thankfully, Bute can only be obtained by a vet prescription.  Because of this, vets will prescribe an exact dosage for your horse. There is no question as to what is an appropriate amount and what is not; your vet will define this for you and your horse.

I hope this article helped you better understand what bute is, what it does, and what its side effects can be if used improperly.  If so, please share this article, and share with us your experiences (good and bad!) with using bute!


For how long can you safely give bute to a horse?

Bute is a medication given to horses as a painkiller and anti-inflammatory. In the olden days, it was one of the most commonly used medications for horses. Today, it has been replaced by other more effective drugs with fewer side-effects.
In general, you should not give bute to a horse for more than three days unless you have been professionally trained to do so or you are under strict veterinary supervision.
The dosage of bute can be varied, depending on the size of the horse, weight and age. The dosage is usually 0.35-0.5 mg per kilogram of weight for a one-time dose or a daily dose of up to 1 mg/kg body weight per day.

Does bute calm a horse down?

The effects of bute depend on the dosage given, as well as the horse's weight. In general, bute will have a calming effect on a horse because of its muscle relaxant properties.
In general, bute will have a calming effect on a horse because of its muscle relaxant properties. This is why it's the most common drug given to horses who are injured or in pain. Bute can also help control pain and inflammation, as well as reduce the risk of infection.
The calming effect from bute will allow for better rest and sleep which in turn promotes healing from injuries sustained by the horse or from other negative stimuli sources such as environmental stressors or illness.

How quickly does bute work?

Bute can be administered as an oral drench, as a slow-release injectable, or as a drench through the skin of the neck or upper back. Most often is injected into horses as a painkiller and it works very quickly. It can be injected into the horse's muscle or vein. As soon as the injection is given, the horse usually starts showing signs of improvement within minutes and can return to normal within 20-30 minutes after injection.
The effects of bute last for four to six hours after administration, with some effects persisting up to 12 hours after administration. The most common sign that bute is taking the effect is sedation. Sedation is typically seen within 30 minutes after ingestion and lasts about 12 hours.

Can bute cause colic?

The risk of taking bute is that it can cause side effects. The most common side effect that occurs in the intestines is stomach ulcers that can lead to development of colic. This happens because after bute is ingested, it becomes the active ingredient in the animal's stomach lining. So over time, the stomach lining can become irritated or even ulcerated due to constant contact with bute.
The most common symptom of stomac ulcers and colic is abdominal pain. Other symptoms may include nausea, vomiting, loss of appetite, diarrhea, weight loss, fever, and impaired range of motion.
Other possible side effects that can occur with bute are liver damage, kidney damage, and abnormal heart rhythms. The chance of these side effects occurring is reduced if the horse is not given bute for a long periods of time.
So, which horses are more likely to react well with bute? Horses that are generally healthy without any underlying conditions will usually tolerate this drug pretty well.