Dexamethasone

Potent glucocorticoid for systemic anti-inflammatory and immunosuppressive therapy; allergic reactions, shock, immune-mediated diseases, airway inflammation in horses and small animals. Potent fluorinated long-acting glucocorticoid. Mechanism: binds glucocorticoid receptors → transactivation/transrepression → inhibits NF-κB, AP-1; induces annexin-1 (inhibits phospholipase A2) → profound reduction in prostaglandin, leukotriene, and cytokine synthesis. ~25× more potent than cortisol. Negligible mineralocorticoid activity due to 9α-fluoro and 16α-methyl substitutions. Long half-life. Key information Potent corticosteroid. Immunosuppressive — increased infection risk. May induce laminitis in horses — use lowest effective dose. May precipitate parturition in mares. Prohibited in competition — know withdrawal times. Adrenal suppression with prolonged use.

Injectable: IV (dilute; Administer IV slowly; rapid infusion may cause adverse reactions.), IM, or intra-articular (aseptic technique). Oral: Administer orally. May be given with food to improve compliance and reduce GI upset. Administer with food to reduce GI adverse effects. Topical (ophthalmic/otic): apply as directed. IV doses for shock/anti-inflammatory: administer as single bolus over 2–5 min. Store at room temperature; protect from light. If a dose is missed Give the missed dose as soon as you remember. If the next dose is due within a few hours, skip the missed dose and resume the regular schedule. Never give a double dose.

HPA axis suppression (most potent of common corticosteroids). PU/PD/polyphagia. Muscle wasting, cachexia. Immunosuppression — increased susceptibility to infections. Laminitis (horses — risk with single large doses). GI: gastric ulceration. Delayed wound healing. Behavioral: excitability, mood changes. Iatrogenic Cushing's syndrome with repeated dosing. Osteoporosis with prolonged use.

For animals Most potent common corticosteroid — high laminitis risk in horses with single large or repeated doses, especially in insulin-dysregulated patients (EMS, PPID, obese horses). Avoid in pregnant animals. Avoid live vaccines. Monitor for GI ulceration; use with caution in animals with GI disease. Do not use concurrently with other NSAIDs or corticosteroids. Do not administer to horses with active laminitis. Adrenal suppression — taper on discontinuation if used > 1 week. For people handling this medication Wear gloves when handling. Wash hands thoroughly with soap and water after handling. Corticosteroid — avoid prolonged skin contact. Keep out of reach of children. Pregnant women and women of childbearing age should avoid contact. Wear gloves when handling injectable or topical forms. Adrenal suppression possible with chronic human exposure.

Contact your veterinarian. A single accidental extra dose of a corticosteroid is usually not a medical emergency, but signs to watch for include extreme lethargy, vomiting, increased thirst/urination, and muscle weakness. Contact your vet before giving the next dose.