Sodium chloride
**Sodium chloride** is a fundamental crystalloid fluid used in veterinary medicine for fluid replacement, electrolyte balance, and as a drug diluent. It is available in hypotonic, isotonic (normal saline), and hypertonic formulations. > **Clinical Pearl:** Hypertonic saline is a potent volume expander used in shock but requires careful monitoring of serum sodium levels and follow-up with isotonic fluids.
Mechanism: Isotonic and hypertonic formulations expand **plasma volume** and replace lost extracellular fluid. Hypotonic formulations provide free water and may promote oedema formation. When used for fluid replacement, NaCl (0.45% and 0.9%) will expand the plasma volume compartment. โ Compared with colloids, 2.5 to 3.0 times as much fluid must be given because the crystalloid is distributed to other fluid compartments.
Dosing by species
- Intravenous fluid replacement (including hypercalcaemia or hyperchloraemic alkalosis) ยท Dose not specified in monograph ยท IV ยท As directed ยท As needed ยท Treatment of choice for hypercalcaemia or hyperchloraemic alkalosis.
- Shock (rapid blood volume expansion) ยท Rate must not exceed 1 ml/kg/min ยท IV ยท As directed ยท Preoperative period or acute crisis ยท Use hypertonic saline. Must monitor serum sodium and follow with isotonic crystalloid.
- Corneal oedema ยท Dose not specified in monograph ยท Topical ยท As directed ยท As needed ยท Use 5% hypertonic ophthalmic ointment.
- Hypoadrenocorticism (long-term management) ยท Dose not specified in monograph ยท PO ยท As directed ยท Long-term ยท Enteric-coated products may have unpredictable efficacy in dogs.
- Intravenous fluid replacement ยท Dose not specified in monograph ยท IV ยท As directed ยท As needed ยท Treatment of choice for hypercalcaemia or hyperchloraemic alkalosis.
- Shock (rapid blood volume expansion) ยท Rate must not exceed 1 ml/kg/min ยท IV ยท As directed ยท Preoperative period or acute crisis ยท Use hypertonic saline. Must monitor serum sodium and follow with isotonic crystalloid.
- Corneal oedema ยท Dose not specified in monograph ยท Topical ยท As directed ยท As needed ยท Use 5% hypertonic ophthalmic ointment.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Dehydrated animals (Hypertonic saline)
- Hypovolaemic animals (Hypotonic solutions)
Adverse effects
- Peripheral oedema
- Hyperchloraemic acidosis (especially in compromised patients)
- Vagally mediated bradycardia (if hypertonic saline is administered >1 ml/kg/min)
- Stinging sensation (ophthalmic ointment)
Monitoring
- Serum sodium concentrations (especially before and after hypertonic saline)
- Acid-base status (monitor for acidosis)
- Heart rate (monitor for bradycardia during rapid hypertonic infusion)
- Hydration status and fluid balance
Overdose
Excessive administration of normal saline can increase the risk of **hyperchloraemic acidosis** and **peripheral oedema**. Administration of hypertonic saline at fluid rates >1 ml/kg/min can cause a **vagally mediated bradycardia**.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.