A Welsh Terrier bitch presented for acute onset and progression of weakness, tetany, and muscle trembling. The bitch had whelped 5 weeks earlier. Initial assessment revealed depression, tetany, muscle trembling, tachypnea, tachycardia, hyperthermia, ventricular premature complexes, hypotension, acidemia, hypocalcemia, and vaginal discharge. Intravenous fluids and calcium gluconate were administered shortly after presentation. This treatment resulted in rapid improvement and resolution of clinical signs. Marked hypocalcemia was confirmed with blood gas analysis and supported a definitive diagnosis of puerperal tetany.