Insulin CRI Calculator (Veterinary)
Estimate the regular-insulin continuous rate infusion (CRI) for diabetic ketoacidosis in dogs and cats, using the standard 250 mL bag method.
How to Use This Calculator
- Select the species — dog (2.2 units/kg/day) or cat (1.1 units/kg/day).
- Enter the patient's weight in kilograms.
- Choose the carrier bag volume (250 mL standard).
- Read the result: units of regular insulin to add to the bag, plus the per-day and per-hour amounts.
The bag is then run on a glucose-based sliding scale (below) with dextrose added as glucose falls. This is an educational reference for veterinary professionals, not for home use.
The Veterinary Insulin CRI Method
For diabetic ketoacidosis in dogs and cats, a low-dose regular insulin CRI is a common protocol. A day's worth of insulin is added to a carrier bag of saline and run alongside fluid therapy, titrated to the glucose response.
This amount is added to a 250 mL bag of 0.9% saline. Example: a 20 kg dog → 20 × 2.2 = 44 units of regular insulin added to 250 mL.
The infusion rate is then adjusted on a sliding scale based on each glucose reading, and dextrose is added to the fluids as blood glucose drops toward normal.
Key Safeguards
- Electrolytes first. Check and replace potassium (and often phosphorus) before and during insulin — insulin shifts them into cells.
- Run insulin line separately and prime/saturate the tubing (regular insulin binds to plastic).
- Lower glucose gradually to avoid cerebral edema; add dextrose as glucose falls.
- Use regular insulin for the CRI — not long-acting products.
Glucose-Based Sliding Scale for the CRI
Once the insulin-saline bag is mixed, the infusion rate is adjusted to each blood-glucose reading, and dextrose is added to the separate fluid line as glucose falls. A widely taught protocol for the 250 mL bag runs roughly:
| Blood glucose (mg/dL) | Insulin-bag rate | Dextrose in fluids |
|---|---|---|
| > 250 | 10 mL/hr | None |
| 200–250 | 7 mL/hr | 2.5% |
| 150–200 | 5 mL/hr | 2.5% |
| 100–150 | 5 mL/hr | 5% |
| < 100 | Stop infusion | 5% |
Representative values only — exact rates depend on the protocol, bag concentration and patient. Aim to lower glucose gradually (about 50 mg/dL/hr) to avoid complications.
Frequently Asked Questions
How much insulin goes in a CRI for a dog or cat?
A common protocol adds regular insulin to a 250 mL saline bag at about 2.2 units/kg/day for dogs and 1.1 units/kg/day for cats, then runs it on a sliding scale to the glucose curve. A 20 kg dog would have about 44 units added to the bag.
Which insulin is used for a veterinary CRI?
Short-acting regular insulin, because it can be titrated minute-to-minute by infusion. Long-acting insulins are not used for a CRI. The IV tubing is usually saturated with the insulin solution first, since regular insulin binds to plastic.
Why monitor potassium during the CRI?
Insulin drives potassium (and phosphorus) into cells, and DKA patients are often already depleted. Without monitoring and replacement, dangerous hypokalemia can develop during treatment.
Can a pet owner give a CRI at home?
No. A veterinary insulin CRI is intensive hospital care requiring IV access, repeated lab monitoring, and a veterinarian. This tool is an educational reference for veterinary professionals only.
How often is blood glucose checked during a CRI?
Typically every 1–2 hours, so the infusion rate and dextrose can be adjusted to the sliding scale. Electrolytes — especially potassium and phosphorus — are usually rechecked every 4–8 hours during DKA treatment.
What is the difference between an insulin CRI and intermittent IM insulin?
A CRI delivers regular insulin continuously through a dedicated line, giving smooth, easily titrated control. The hourly intramuscular protocol (often a small loading dose then ~0.1 units/kg IM hourly) is an alternative when an infusion pump or second line isn't available. Both use short-acting regular insulin and the same gradual-lowering goal.
Sources
- Behrend E, et al. "2018 AAHA Diabetes Management Guidelines for Dogs and Cats." J Am Anim Hosp Assoc. 2018.
- Standard veterinary DKA low-dose regular-insulin CRI protocols.
Last reviewed: June 2025