Phenylbutazone

Indications

For relief of inflammatory conditions associated with the musculoskeletal system in horses.

Dosage and Administration

HORSES INTRAVENOUSLY : 1 to 2 g per 1,000 lbs of body weight (5 to 10 mL/1,000 lbs) daily. Injection should be given slowly and with care. Limit intravenous administration to a maximum of 5 successive days, which may be followed by oral phenylbutazone dosage forms. GUIDELINES TO SUCCESSFUL THERAPY 1. Use a relatively high dose for the first 48 hours, then reduce gradually to a maintenance dose. Maintain lowest dose capable of producing desired clinical response. 2. Response to phenylbutazone therapy is prompt, usually occurring within 24 hours. If no significant clinical response is evident after 5 days, reevaluate diagnosis and therapeutic approach. 3. In animals, phenylbutazone is largely metabolized in 8 hours. It is recommended that a third of the daily dose be administered at 8 hour intervals. Reduce dosage as symptoms regress. In some cases, treatment may be given only when symptoms appear with no need for continuous medication. If long-term therapy is planned, oral administration is suggested. 4. Many chronic conditions will respond to phenylbutazone therapy, but discontinuance of treatment may result in recurrence of symptoms.

Contraindications

Treated animals should not be slaughtered for food purposes. Parenteral injections should be made intravenously only; do not inject subcutaneously or intramuscularly. Use with caution in patients who have a history of drug allergy.

Precautions

Stop medication at the first sign of gastrointestinal upset, jaundice, or blood dyscrasia. Authenticated cases of agranulocytosis associated with the drug have occurred in man. To guard against this possibility, conduct routine blood counts at weekly intervals of two weeks thereafter. Any significant fall in th total white count, relative decrease in granulocytes, or black or tarry stools, should be regarded as a signal for immediate cessation of therapy and institution of appropriate counter measures. In the treatment of inflammatory conditions associated with infections, specific anti-infective therapy is required. Store in refrigerator between 2 o - 8 o C (36 o - 46 o F)

Other labels for this ingredient

These labels are also stored for the same active ingredient. They are not identical to the one reprinted above, and each is listed by product and set id rather than merged with it.

• PHENYLBUTAZONE 20% INJECTION 200 mg/mL, MWI/VetOne. Set id 1de8a19f-c5e6-4e5a-9c38-36b18c9adab3.
• Phenylbutazone, Covetrus North America. Set id 2ee44546-5bff-4bbe-918b-12da6e516bcc.
• Phenylbutazone 20% Injection 200 mg/mL, Aspen Veterinary Resources, Ltd.. Set id 340d310d-7987-4f9c-ae39-eab2340d8f74.
• EQUI-PHAR PHENYLBUTAZONE 20% INJECTION 200 mg/mL, Vedco, Inc.. Set id 5dd8b3b7-edfb-46f9-a7f2-b87a1ad06b6c.
• VETONE Phenylbutazone Powder, MWI/VetOne. Set id 0e697281-de74-4457-984d-558162f927fb.
• PHENYLBUTE (phenylbutazone) Powder, Clipper Distributing Company LLC. Set id 1924222f-a5b7-4fc9-9d6d-e9277c1fb01b.
• EQUIZONE 50/100 (phenylbutazone) Powder, A&G Pharmaceuticals. Set id 6f7796e9-567c-4ea6-8748-030da333e7bb.

FDA adverse event reports

The FDA Center for Veterinary Medicine publishes the adverse event reports it receives through openFDA. The counts below are the reports naming phenylbutazone as an active ingredient for each species this label names, as returned on 2026-09-16, coded by the VeDDRA reaction term the reporter chose. Reactions are counted per report, so one report can appear under several terms.

These are counts, not rates. Reporting is voluntary, the number of animals treated is not known, and a widely used product accumulates reports for that reason alone. A report records that an event followed a dose; it does not establish that the product caused it. The counts say nothing about how one product compares with another.