Fludrocortisone: veterinary dose and monograph

At a glance

Drug class

Veterinary drug

Also known as

Florinef, Fludrocortisone acetate

Species with doses

Dogs, Cats and Ferrets

General dose range

0.01–0.02 mg/kg PO q12–24h — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Maintenance therapy of primary hypoadrenocorticism (Addison's disease)
• Mineralocorticoid replacement to normalise sodium and potassium
• Selected cases of hyperkalaemia/hyponatraemia from aldosterone deficiency

Fludrocortisone dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Addison's maintenance: Papich 5e: 10 µg/kg/day PO, increasing up to 30 µg/kg/day by electrolytes. Plumb’s p.534: 0.01 mg/kg PO twice daily (Panciera; Scott-Moncrieff); 0.01–0.02 mg/kg/day adjusted in 0.05–0.1 mg steps — most dogs end up on 0.02–0.03 mg/kg/day (Kintzer 2004). Recheck Na/K every 1–2 weeks until stable, then every 3–4 months. About half need prednisone as well.

Cats

• Addison's maintenance (rare): Plumb’s p.534: 0.02 mg/kg PO once daily with prednisolone 1.25 mg per cat (Scott-Moncrieff 2010); 0.1 mg per cat once daily with prednisolone 0.2 mg/kg (Caney 2009). Papich 5e: 0.1–0.3 mg per cat q24h. Dose to electrolytes.

Ferrets

• Hypoadrenocorticism (post-adrenalectomy): Plumb’s p.534 (Johnson 2006): 0.05–0.1 mg/kg PO q24h or divided q12h if Addisonian signs persist on prednisone.

Contraindications

Congestive heart failure, hypertension, significant renal impairment with sodium-retention concerns, and oedematous states (mineralocorticoid sodium/water retention). Systemic fungal infection (glucocorticoid component). Use caution where potassium is already low. Known hypersensitivity.

Species-specific warnings

Dogs: During stress, illness or surgery, increase glucocorticoid cover — fludrocortisone alone may not supply enough glucocorticoid for stress demands.

Adverse effects

• Polyuria/polydipsia (common — partly mineralocorticoid, partly glucocorticoid)
• Hypertension, sodium/water retention, oedema
• Hypokalaemia at higher doses
• Glucocorticoid effects (panting, weight gain) from its intrinsic glucocorticoid activity

Drug interactions

• Potassium-wasting diuretics (furosemide, thiazides): additive hypokalaemia
• NSAIDs: increased sodium retention/GI risk
• Insulin/oral hypoglycaemics: glucocorticoid effect may raise glucose
• Drugs lowering potassium: monitor closely

Pregnancy and lactation

Used when essential to maintain an Addisonian dam; corticosteroid exposure warrants caution but untreated hypoadrenocorticism is life-threatening — continue replacement and monitor.

Monitoring

• Serum sodium and potassium (Na:K ratio) — the key efficacy markers; recheck after dose changes and periodically
• Blood pressure
• Body weight, PU/PD, signs of glucocorticoid excess
• Renal values

Toxicity and overdose

Overdose/excess produces mineralocorticoid effects — hypertension, sodium/water retention with oedema, hypokalaemia and possible weakness/arrhythmia — plus glucocorticoid excess (PU/PD, iatrogenic Cushingoid signs). Under-dosing risks an Addisonian crisis (the more dangerous direction).

Management: No specific antidote. Reduce/withhold dose; correct electrolytes (treat hypokalaemia, manage hypertension/oedema); supportive care. For glucocorticoid excess, taper. Recheck Na/K and adjust the maintenance dose.

Clinical pearls

• Titrate fludrocortisone to the electrolytes (Na:K ratio), not to a fixed dose — many dogs creep upward in dose requirement over the first year
• Its built-in glucocorticoid activity means some Addisonians need little/no extra prednisolone — but add low-dose glucocorticoid and always increase steroid cover during stress/illness
• DOCP injection is the alternative mineralocorticoid; fludrocortisone suits owners who prefer daily tablets and dogs needing combined gluco/mineralocorticoid effect
• PU/PD is common — distinguish acceptable drug effect from over-dosing by checking electrolytes and blood pressure
• Never abruptly stop in an Addisonian — risk of life-threatening crisis

Mechanism of action

Binds the mineralocorticoid (aldosterone) receptor in the distal nephron, driving sodium (and water) reabsorption and potassium/hydrogen-ion excretion — correcting the hyponatraemia and hyperkalaemia of aldosterone deficiency. Its fluorination greatly amplifies mineralocorticoid potency; it also retains meaningful glucocorticoid activity at the receptor.

Formulations and products

• 0.1 mg tablet (Florinef)
• Florinef — 0.1 mg tablet, Tablet (human-label)

Storage

Tablets: 15–25 °C, dry, protected from light.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

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• Fomepizole (4-MP)

Frequently asked questions