Crystalloid bolus in canine hypovolaemic shock
5-year-old 32 kg German Shepherd with haemorrhagic diarrhoea and vomiting since yesterday. No history of heart disease. Pale mucous membranes, CRT 3 s, weak pulses and cold extremities.
| Parameter | Result | Reference |
|---|---|---|
| Heart rate | 175 bpm | 70–120 |
| Systolic pressure (Doppler) | 75 mmHg | 110–160 |
| Lactate | 5.1 mmol/L | < 2.5 |
What is the most appropriate initial fluid plan?
chevron_right Show answer and explanation
A. Give the full shock dose (90 mL/kg) at once in the first hour
This approximates the dog's blood volume, not a target. Giving it without reassessment increases the risk of overload, interstitial oedema and dilution of clotting factors.
B. Fluids at 2–3 times the maintenance rate and review in 4 hours
That is a rehydration rate, not a resuscitation rate. A dog with signs of hypoperfusion needs intravascular volume restored within minutes.
C. Isotonic crystalloid bolus of 10–20 mL/kg over 15–20 minutes, reassess and repeat according to response
Correct. For 32 kg that is about 320–640 mL of a balanced crystalloid. After each bolus, heart rate, pulse, mucous membranes, CRT, blood pressure and lactate are reassessed to decide whether to repeat.
D. Synthetic colloid at 20 mL/kg as first choice because it stays longer in the vessels
Synthetic colloids have not shown advantages over crystalloids and are associated with kidney injury and coagulation disorders. They are not first choice.
lightbulb Key takeaway
Resuscitate with boluses: 10–20 mL/kg in dogs and 5–10 mL/kg in cats over 15–20 minutes, reassessing after each. Targets are clinical (perfusion), not a fixed volume.
References: AAHA Fluid Therapy Guidelines for Dogs and Cats (2024)
Test yourself with 10 random questions
Emergency and critical care · 100 questions, a different test every time
Related questions
Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.