Sodium Nitroprusside: veterinary dose and monograph

At a glance

Drug class

Cardiovascular

Also known as

SNP, Nipride, Sodium nitroprusside

Species with doses

Dogs and Cats

Routes

IV

Last reviewed

1 October 2026

Indications

• Hypertensive emergency / crisis — rapid, titratable blood-pressure reduction
• Acute fulminant congestive heart failure / cardiogenic pulmonary oedema (afterload + preload reduction)
• Controlled hypotension during certain procedures (specialist)

Sodium Nitroprusside 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

• Hypertensive crisis / acute CHF (CRI): Papich 5e: 1–5 µg/kg/min, maximum 10; start at 2 and increase by 1 µg/kg/min until the target pressure is reached. Plumb’s p.897: hypertensive crisis start 1–2 µg/kg/min, titrate every 3–5 min and lower BP by 25% over 4 h; fulminant pulmonary oedema usually 2–5 µg/kg/min (upper limit 8–10) for 12–48 h, often with dobutamine. Keep systolic >90 mmHg; continuous BP monitoring. Protect the solution from light; cyanide toxicity with infusions >3 days.

Cats

• Hypertensive crisis / acute CHF (CRI): Plumb’s p.897: start 0.5 µg/kg/min, increasing every 3–5 min to the target (Proulx); pulmonary oedema usually 1–2 µg/kg/min with an upper limit of 2 (Lichtenberger). Papich 5e (dogs and cats): 1–5 µg/kg/min, maximum 10. Cats are more sensitive to oxidative damage — keep total dose minimal; dedicated line, never flush; continuous monitoring.

Contraindications

Without continuous blood-pressure monitoring / ICU setting. Hypovolaemia, severe hypotension, and compensatory hypertension (e.g. raised ICP, AV shunts). Significant hepatic/renal impairment (cyanide/thiocyanate accumulation). Prolonged/high-dose infusion (cyanide toxicity). Known hypersensitivity.

Species-specific warnings

Cats: Use lower infusion rates and meticulous continuous BP monitoring; cats are sensitive to hypotension.

Adverse effects

• Profound hypotension, reflex tachycardia
• Cyanide / thiocyanate toxicity with prolonged/high-dose use (metabolic acidosis, tachypnoea, mentation change)
• Rebound hypertension if stopped abruptly after prolonged use
• Nausea; methaemoglobinaemia (rare)

Drug interactions

• Other vasodilators/antihypertensives (incl. PDE5 inhibitors): additive, potentially severe hypotension
• Drugs depleting thiosulphate: increased cyanide toxicity risk
• Negative inotropes/anaesthetics: additive hypotension

Pregnancy and lactation

Reserve for life-threatening maternal hypertension/CHF; cyanide can cross the placenta — minimise dose/duration.

Monitoring

• CONTINUOUS blood pressure (ideally invasive/arterial) and heart rate — titrate to target
• Infusion rate/duration and cumulative dose (cyanide risk) — limit high-dose/prolonged use
• Acid–base/lactate (cyanide surveillance); mentation
• Light protection of the infusion; taper to avoid rebound hypertension

Toxicity and overdose

Two dose-/duration-dependent hazards: (1) profound hypotension (titration-related), and (2) CYANIDE/thiocyanate toxicity — metabolic (lactic) acidosis, tachypnoea, altered mentation, and cardiovascular collapse — especially with high doses (>~10 mcg/kg/min), prolonged infusion (>24–48 h), or hepatic/renal impairment. Methaemoglobinaemia is a rare additional effect.

Management: STOP the infusion (hypotension reverses within minutes). For suspected CYANIDE toxicity: sodium thiosulphate (and hydroxocobalamin) ± sodium nitrite per cyanide-antidote protocols, plus supportive care and correction of acidosis. Support blood pressure (fluids/vasopressor) and ventilation; monitor lactate/acid–base.

Clinical pearls

• The most titratable vasodilator — instantaneous on/off makes it ideal for hypertensive crises and fulminant CHF, but it DEMANDS continuous BP monitoring (ICU)
• Balanced arterial + venous dilation reduces both afterload and preload
• Mind CYANIDE: keep doses ≤~10 mcg/kg/min, limit duration, and watch for metabolic acidosis — have thiosulphate available
• Protect from light (it degrades), dilute fresh, and taper to avoid rebound hypertension

Mechanism of action

Nitroprusside spontaneously releases nitric oxide in the bloodstream, activating guanylate cyclase in vascular smooth muscle and raising cyclic GMP, which relaxes BOTH arterial (afterload) and venous (preload) smooth muscle — producing rapid, balanced vasodilation. Its metabolism releases cyanide ions (detoxified to thiocyanate by the liver, requiring thiosulphate/B12 cofactors and renal excretion), which accumulate and become toxic with prolonged or high-dose infusion or organ impairment.

Formulations and products

• Injection 50 mg vial (reconstitute, dilute for CRI)
• Sodium Nitroprusside (Nipride) — 50 mg vial (reconstitute), Injection (CRI, light-protected) (human-label)

Storage

Vial: protect from LIGHT (degrades rapidly); reconstitute and dilute fresh, wrap the bag/line in opaque cover, and discard if discoloured (blue/dark). Use within ~24 h.

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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Frequently asked questions