Calculating the correct fluid rate is critical in feline veterinary medicine. Unlike dogs, cats have a smaller blood volume relative to their body weight and are significantly more prone to fluid overload, which can lead to pulmonary edema or congestive heart failure. This calculator uses the standard components of fluid therapy: Maintenance, Rehydration (Deficit), and Ongoing Losses.
1. Maintenance Fluid Rate
Maintenance fluids are required to support basic physiological functions like respiration, metabolism, and urine production. While older formulas often used 60ml/kg/day, modern feline guidelines suggest a more conservative approach for indoor, inactive cats to prevent over-hydration.
Formula used: 50 ml/kg/day (Approximation for adult cats).
Note: For kittens or extremely active cats, requirements may be higher.
2. Dehydration Deficit
This component replaces fluid that has already been lost from the body tissues. It is calculated based on the estimated percentage of dehydration assessed during the physical exam.
Formula: Body Weight (kg) × % Dehydration × 10 = Deficit in Liters (converted to ml in this tool).
Example: A 4kg cat with 5% dehydration has a deficit of 4 × 5 × 10 = 200 ml.
3. Ongoing Losses
If the patient is continuing to lose fluids through vomiting, diarrhea, or excessive urination (polyuria), these anticipated losses must be added to the fluid plan to prevent the cat from falling behind again.
Calculating the Hourly Rate
The final flow rate (ml/hr) is determined by summing the daily maintenance needs, the deficit (usually replaced over 12-24 hours), and the anticipated ongoing losses, then dividing by the number of hours in the plan.
Warning: Always monitor respiratory rate and heart rate closely when administering IV fluids to cats. If signs of fluid overload occur (increased respiratory rate/effort, chemosis), stop fluids immediately and reassess.