Dr Duncan HoustonWritten and reviewed by a practising veterinarian · Last updated 19 August 2026

Diabetic Crisis Calculator — DKA vs HHS

Classify the crisis, then work through osmolality, corrected sodium, free water deficit, the fluid plan, safe correction rates, potassium and insulin — for dogs and cats.

Patient & admission values

Start with the patient and the admission bloods

Enter pretreatment values where possible. Missing values stay unknown and are never silently treated as normal.

Species

Units

Switches weight, glucose and urea/BUN conventions. Osmolality remains mOsm/kg and fluid volumes remain mL.

Body weight (kg)

Estimated dehydration (%)

5% subtle · 8% obvious · 10–12% severe.

Diabetes mellitus context

Use “known / supported” for established DM or compatible persistent hyperglycaemia with glucosuria and/or increased fructosamine. Stress hyperglycaemia alone does not confirm DM.

Blood glucose

Sodium — Na⁺ (mmol/L)

Potassium — K⁺ (mmol/L)

Chloride — Cl⁻ (mmol/L)

Optional. Used for the anion gap.

Urea (mmol/L)

Optional. Affects total osmolality, not tonicity.

Measured serum osmolality (mOsm/kg)

Optional comparison value. Classification always uses calculated effective osmolality: 2 × measured Na + glucose.

Venous pH

Bicarbonate — HCO₃⁻ (mmol/L)

Interpret with pH and the anion gap.

Ketones — source

Blood β-hydroxybutyrate (mmol/L)

Urine ketones (dipstick)

Dipsticks detect acetoacetate rather than BHB and may under-read early DKA. Confirm with blood BHB when possible.

SGLT2 inhibitor exposure in this cat

Bexagliflozin, velagliflozin or another SGLT2 inhibitor raises concern for euglycaemic DKA even below 250 mg/dL.

View current classification

Correction targets

Set the correction targets

Set the sodium goal and deficit-replacement interval used by the fluid estimates.

Target sodium (mmol/L)

Correct deficit over

Use a slower interval for hypertonicity or marked hypernatraemia.

Insulin protocol setup

Choose the insulin protocol

These dose tables use regular (soluble/neutral) insulin. Do not substitute another product into the calculations.

Delivery protocol

Insulin added to bag (U/kg)

0.9% NaCl carrier volume (mL)

Standard 250 mL. Pump rates recompute if changed.

Classification

Classification and treatment plan

Everything below recalculates as you type. There is nothing to submit.

For qualified veterinary use only. This calculator is decision support, not a substitute for clinical judgement, serial monitoring, or up-to-date references. Formulae assume adult patients and can behave unexpectedly at extreme values. Always re-check electrolytes, glucose and neurological status frequently, and adjust to the individual patient.

How this tool works

Method and clinical references

Method: effective osmolality = 2 × measured Na + glucose; total calculated osmolality = 2 × measured Na + glucose + urea (SI). The HHS flag uses effective osmolality >320 mOsm/kg and glucose >600 mg/dL. Corrected Na uses +1.6 mmol/L per 100 mg/dL glucose above 100 for the primary estimate; +2.4 is shown only as a secondary human-derived estimate. Anion gap = (Na + K) − (Cl + HCO₃). Formula choice and analyser intervals matter.

Clinical references: ALIVE 2026 companion-animal DKA consensus · iCatCare 2025 feline diabetes consensus · AAHA 2026 feline DKA guidance · Merck Veterinary Manual · 2024 canine sodium-correction study · canine BHB study · feline BHB study. Last clinically reviewed 19 August 2026.

About the author

Dr Duncan Houston · BVSc, Veterinarian

Emergency careGeneral practiceMobile vet careFounder, ASK A VET™

Dr Duncan Houston is an Australian veterinarian with experience in emergency, general-practice and mobile veterinary care. He is the founder of ASK A VET™. This guide is educational and is not a substitute for hands-on veterinary care.