Phenylbutazone Injectable 20% is a synthetic, non-hormonal, anti-inflammatory, antipyretic compound useful in the relief of inflammatory conditions associated with the musculoskeletal system in horses. 200mg/mL. Intravenous dosage not for subcutaneous or intramuscular use: Horses: 1 to 2g per 1,000lb body weight 5 to 10mL/1,000lb daily. Not for use in horses intended for food.