Clinical decision support
Blood gas analyzer
Interpret acid-base disorders, calculate anion gap with albumin correction, assess compensation, and estimate osmolality from blood gas and electrolyte values.
Safety checks
- Reference ranges: Dog pH 7.35–7.45, Cat pH 7.31–7.41. pCO₂ dog 35–45, cat 29–42 mmHg. HCO₃⁻ dog 22–26, cat 17–23 mEq/L.
- Albumin correction: Anion gap is adjusted for hypoalbuminemia using the formula: AG + (2.5 × [3.5 − albumin]).
- Delta ratio: Values <1 suggest concurrent non-anion gap metabolic acidosis; >2 suggests concurrent metabolic alkalosis.
- What still needs checking: Patient hydration status, lactate, electrolyte trends, and clinical picture before fluid or bicarbonate therapy.
Basis and limits
- Primary disorder: pH < 7.35 = acidemia; > 7.45 = alkalemia. Low HCO₃⁻ with low pH = metabolic acidosis. High pCO₂ with low pH = respiratory acidosis. High HCO₃⁻ with high pH = metabolic alkalosis. Low pCO₂ with high pH = respiratory alkalosis.
- Compensation (Winter's formula): Expected pCO₂ = (1.5 × HCO₃⁻) + 8 ± 2. For metabolic alkalosis: expected pCO₂ = (0.7 × HCO₃⁻) + 20 ± 1.5.
- Respiratory compensation: Acute: HCO₃⁻ changes ~0.15 mEq/L per 1 mmHg pCO₂ change. Chronic: ~0.35 mEq/L per 1 mmHg.
- Anion gap: Na − (Cl + HCO₃). Normal dog ~12–24, cat ~13–27. Albumin-corrected AG adds 2.5 mEq/L per 1 g/dL albumin below 3.5.
- Osmolality: 2(Na) + glucose/18 + BUN/2.8. Normal ~290–310 mOsm/kg. Osmolar gap > 15 suggests unmeasured osmoles (toxins, mannitol).
Formula audit trail
Calculation steps will appear here for verification.
Last reviewed: May 2026
Sources: Merck Veterinary Manual; DiBartola's Fluid, Electrolyte, and Acid-Base Disorders