Dehydration without hypovolaemia in the cat: how to rehydrate
13-year-old female domestic shorthair with chronic kidney disease, not eating for three days. Dry, tacky mucous membranes, sunken eyes, estimated 8% dehydration. Heart rate 190 bpm, strong pulses, CRT 1.5 s, systolic pressure 140 mmHg and normal lactate.
What is the most appropriate fluid plan?
chevron_right Show answer and explanation
A. Repeated 10 mL/kg boluses until the skin tent disappears
Boluses are for hypovolaemia, not interstitial dehydration. Moreover, skin tent is unreliable in older, thin cats, and chasing it causes overload.
B. Intravenous fluids replacing the deficit over 12–24 hours, plus maintenance and losses, monitoring body weight
Correct. The cat is dehydrated (interstitial deficit) but not hypovolaemic: perfusion, blood pressure and lactate are normal. The deficit is replaced gradually; in a cat with CKD and possible occult heart disease, monitor respiratory rate and weight.
C. Subcutaneous fluids at home as the only treatment
With 8% dehydration and anorexia, subcutaneous absorption is slow and insufficient; subcutaneous fluids are for maintenance in stable CKD.
D. Replace the entire deficit within 2 hours to improve renal function as soon as possible
Such rapid replacement in a normovolaemic cat exceeds redistribution capacity and promotes pulmonary oedema and pleural effusion.
lightbulb Key takeaway
Dehydration (water deficit in the interstitium) and hypovolaemia (volume deficit in the vessels) are not the same. Hypovolaemia is treated with boluses over minutes; dehydration with gradual replacement over 12–24 hours.
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.