How much is too much during anesthesia fluid therapy?

Version 1

A new dvm360 clinical article from Lydia Love, DVM, DACVAA, urges veterinarians to rethink how much IV crystalloid they give during routine anesthesia by anchoring decisions to plasma volume, not habit. Love’s rule of thumb is that plasma volume is roughly 45 to 50 mL/kg in dogs and cats, so once an anesthetized patient has received more than about 15 to 20 mL/kg, and especially as the total approaches 30 mL/kg, the team should stop and reassess whether more fluid is actually helping or simply pushing the patient toward overload. That framing aligns with the 2024 AAHA Fluid Therapy Guidelines, which note that older 10 mL/kg/hr anesthesia rates lacked strong evidence and recommend lower starting rates of 5 mL/kg/hr in dogs and 3 to 5 mL/kg/hr in cats, with close monitoring of total administered volume and signs of excess. (aaha.org)

Why it matters: For veterinary professionals, the message is less about a new hard cutoff and more about a shift toward individualized, goal-directed fluid therapy. AAHA advises reevaluating fluid administration if total intra-anesthetic volume surpasses 20 mL/kg, and lists warning signs of overload including chemosis, tissue edema, clear nasal discharge, pulmonary crackles, low SpO2, pleural effusion, and ascites. Broader veterinary anesthesia literature also supports moving away from standardized formulas and toward patient-specific monitoring, noting that fluid therapy alone is often an incomplete fix for anesthetic hypotension and can predispose patients to fluid overload if used reflexively. (aaha.org)

What to watch: Expect more discussion around anesthesia protocols that emphasize lower default fluid rates, dynamic monitoring, and earlier use of anesthetic adjustment or vasoactive support instead of repeated fluid escalation. (aaha.org)