Hypertonic saline in canine haemorrhagic shock
5-year-old 60 kg Newfoundland bleeding from a deep limb wound, now under compression. Pale mucous membranes, CRT 3 s and weak pulses. So far only a narrow-gauge peripheral catheter is in place.
Which statement about hypertonic saline is correct?
chevron_right Show answer and explanation
A. Its volume-expanding effect lasts several hours, so no further fluids are needed
The sodium redistributes into the interstitium within 30–60 minutes and the effect wears off. It must always be followed by isotonic crystalloids or blood products.
B. About 3–5 mL/kg is given over 5–10 minutes; it draws water from the interstitium and rapidly expands volume
Correct. A small volume achieves rapid expansion, useful in large dogs or when replacement is slow. It is followed by isotonic crystalloids to replace the mobilised interstitial water.
C. It is the best option in severely dehydrated or hypernatraemic patients
It is contraindicated in both: it needs interstitial water to mobilise and would worsen hypernatraemia.
D. It can be given as a direct bolus in under a minute without risk
Too rapid administration can cause bradycardia, transient hypotension and arrhythmias. It is given over 5–10 minutes.
lightbulb Key takeaway
Hypertonic saline "buys time": it expands volume with little fluid, but its effect is brief and depends on interstitial water. Avoid it in dehydration and hypernatraemia and always follow with isotonic crystalloids.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.