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Phenylbutazone by VetOne

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Phenylbutazone (for horses)

Trade Names:
ButaTabs E
Butatron® Tablets
Bute Boluses
Equi-Bute™ Paste
Equi-Phar ButePaste
Equi-Phar™ Phenylbutazone Injection 20%
Phenylbutazone 20% Injection
Phenylbutazone Powder
Phenylbutazone Tablets
Phenylbutazone Tablets (1 g)
Phenylbute® Boluses 1 gram
Phenylbute® Injection 20%
Phenylbute® Paste
Phenylbute® Powder
Phenylzone® Paste
Pributazone® Boluses
Pro-Bute™ Injection
VetriBute™ Paste

General Description:

Phenylbutazone is a nonsteroidal anti-inflammatory drug (NSAID) used in horses to control pain and inflammation in the muscles and bones, and to reduce fever. The oral medication should be given with food. The injectable form should only be given I.V. as it will cause pain and/or tissue damage otherwise. Other NSAIDs should be used in dogs and cats as they have fewer toxic side effects than Phenylbutazone.

What is this drug?
• Phenylbutazone is an NSAID (non-steroidal anti-inflammatory); non-narcotic
• Oral Phenylbutazone (powder, paste or tablet) is given by mouth with food and the injectable form should ONLY be given intravenously (I.V.)

Reasons for prescribing:

To treat pain and inflammation in horses, especially good for osteoarthritis
Reduces fever

What horses should not take this medication?
• Horses with anemia, bleeding problems, liver, kidney or heart disease
• Horses who are dehydrated or have gastric ulcers
• Foals and ponies as they are more sensitive to the side effects
• Pregnant or nursing animals
• Do not use in animals intended for use in food
• For ethical reasons, do not use in animals prior to a soundness exam as it may mask lameness
• Horses with known hypersensitivity to NSAIDs


Give the exact amount prescribed and only as often as directed. Missed doses reduce the effectiveness of therapy.
If you have difficulty giving Phenylbutazone as prescribed, consult your veterinarian. The dosage form may be able to be changed or another administration technique could be used that is more acceptable to both you and your horse.
Do not mix any other drugs in the same syringe as Phenylbutazone injection.
Do not allow your horse to become dehydrated while on Phenylbutazone. Ensure your horse has adequate access to clean drinking water.
Ideally, give the medication at the same time daily.

What if dose is missed?

If a dose is missed, give it as soon as you can. If it is time already for the next dose, skip the missed dose and go back to the normal schedule. Do not give two doses at the same time.

What to tell/ask veterinarian before giving medication?

Talk to your veterinarian about:
• When will your horse need to be rechecked
• What tests may need to be performed prior to and during treatment with this drug
• Risks and benefits of using this drug

Tell your veterinarian about:
• If your horse has experienced side-effects on other drugs/products
• If your horse has experienced digestive upset now or ever
• If your horse has experienced liver or kidney disease now or ever
• If your horse has experienced any other medical problems or allergies now or ever
• All medicines and supplements that you are giving your horse or plan to give your horse, including those you can get without a prescription. Your veterinarian may want to check that all of your horse's medicines can be given together.
• If your horse is pregnant or nursing or if you plan to breed your horse

Storage and Warnings:

Oral Phenylbutazone should be stored in a tight, light resistant, childproof container in a cool, dry place at room temperature away from heat and direct sunlight. Injectable Phenylbutazone should be refrigerated.
Keep this and all medication out of reach of children and pets.
Call your physician immediately if you accidentally take this product.

Potential side effects:
• Stomach irritation and vomiting
• May cause mouth or stomach ulcers
• Contact your veterinarian if your horse won’t eat, is depressed, has diarrhea, changes drinking or urination habits, is painful or grinds his teeth
• May cause bone marrow suppression and anemia (pale gums, weakness) and/or low white blood cell numbers which can make your horse more susceptible to infections
• May be detectable in the urine for at least 7 days following administration
• May alter laboratory test results. Inform your veterinarian of drug usage prior to any laboratory testing.
• Allergy symptoms to this medication include: scratching, facial swelling, hives, sudden diarrhea, vomiting, shock, seizures, pale gums, cold limbs, or coma
• It is important to stop therapy and contact your veterinarian immediately if you think your horse has a medical problem or side effect from this product's therapy

Can this drug be given with other drugs?
• Yes, but possible interactions may occur with aspirin, barbiturates, chlorpheniramine, corticosteroids, digoxin, diphenhydramine, diuretics, glipizide, penicillin, phenytoin, other NSAIDs or ulcer-causing medications, rifampin, sulfonamides, valproic acid, warfarin or drugs that may cause liver damage.
• Misoprostol may be useful to prevent stomach ulcers due to Phenylbutazone usage
• If your horse experiences any unusual reactions when taking multiple medications, contact your veterinarian


If you see decreased urine production and/or bloody urine, depression, jaundice, fever, anemia (pale gums and weakness), ulcers and/or colic, or if your horse receives more than the prescribed amount of drug, contact your veterinarian immediately.

What else should I know?

Notify your veterinarian if your animal's condition does not improve or worsens despite this treatment.

As with all prescribed medicines, Phenylbutazone should only be given to the horse for which it was prescribed. It should be given only for the condition for which it was prescribed.

This is just a summary of information about Phenylbutazone. If you have any questions or concerns about Phenylbutazone or for the condition it was prescribed, contact your veterinarian.

(Butazolidin, Phenylbute)

Common Drug Name

Common Brand Names
Butazolidin, Phenylbute
Generic products are available.

Store at room temperature in a tight, light resistant, childproof container. Store injectable between 46-56°, or refrigerate.

Phenylbutazone is a non-steroidal anti­inflammatory drug (NSAID) used to relieve pain and inflammation of muscles and bones in horses.
Because of more toxic side effects of phenylbutazone in dogs and cats, other NSAIDs should be used in these species.

Dose and Administration
Always follow the dosage instructions provided by your veterinarian. If you have difficulty giving the medication, contact your veterinarian.
The oral form should be given with food.
The injectable form should only be given in the vein (intravenously, IV). Do NOT give subcutaneously (under the skin, subQ) or intramuscularly (into the muscle, IM), since it will cause pain and tissue damage. Do not administer intra-arterially (into an artery); it will cause seizures.  
If you miss a dose, give it as soon as you remember. If it is almost time for the next dose, skip the one you missed and go back to the regular schedule. Do not give 2 doses at once.
This medication should only be given to the horse for whom it was prescribed.

Possible Side Effects
May cause stomach irritation and vomiting. May cause ulcers of the mouth or stomach. If your horse stops eating, becomes depressed, has diarrhea, seems in pain, or grinds his teeth, contact your veterinarian.
May cause bone marrow suppression resulting in anemia (with pale gums and weakness) and/or low white blood cell counts with an increased susceptibility to infections.
If your horse changes his drinking or urinating habits, consult your veterinarian immediately.
If your horse experiences an allergic reaction to the medication, signs may include facial swelling, hives, scratching, sudden onset of diarrhea, vomiting, shock, seizures, pale gums, cold limbs, or coma. If you observe any of these signs, contact your veterinarian immediately.

Not for use in animals hypersensitive (allergic) to it or other NSAIDs.
Do not use in animals who are dehydrated or have stomach ulcers; anemia or bleeding disorders; or liver, kidney, or heart disease.
Do not allow your horse to become dehydrated while taking phenylbutazone. Keep plenty of clean drinking water available.
Do not use in foals and ponies; they are more sensitive to its side effects.
Do not use in pregnant or lactating animals (female animals nursing their young).
Do not use in animals that are going to be used for human food.
Phenylbutazone may mask lameness, and it is unethical to use it prior to a soundness exam.
Consult with your veterinarian regarding physical examinations and laboratory testing necessary prior to, and during, treatment with phenylbutazone.

Drug, Food and Test Interactions
Consult your veterinarian before using phenylbutazone with any other medications, including vitamins and supplements, or other NSAIDs, cortico­steroids, aspirin, or other ulcer-causing medications, barbiturates, rifampin, corticosteroids, chlorpheniramine, or diphenhydramine, other drugs that could damage the liver, or with diuretics. (e.g., furosemide, Lasix), since interactions may occur.
Misoprostol may reduce the risk of stomach ulcers resulting from the use of phenylbutazone.
May increase levels or prolong duration of action of penicillin, phenytoin, valproic acid, warfarin, NSAIDs, and sulfonamides. 
With long-term use, may decrease the effectiveness of phenytoin and digoxin.
Phenylbutazone may be detected in the urine for at least 7 days following administration.
Phenylbutazone may alter the result of laboratory tests. Inform your veterinarian that your horse is taking phenylbutazone prior to any lab testing.

Signs of Toxicity/Overdose
May see decreased urine production and blood in the urine; jaundice (yellowing of the skin, gums, and eyes); anemia (pale gums and weakness); colic, and ulcers. 
If you know or suspect your pet has had an overdose, or if you observe any of these signs in your horse, contact your veterinarian immediately.
Keep this and all other medications out of the reach of children and pets.

This information may not cover all possible uses, directions, side effects, precautions, allergic reactions, drug interactions, or withdrawal times.  Always consult your own veterinarian for specific advice concerning the treatment of your pet.


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