Pseudo-Addisonian Crisis With Hyponatremia and Hyperkalaemia in a Late Pregnant Bitch

A 3-year-old pregnant Golden Retriever bitch was presented 52 days after ovulation for nausea, hyporexia, regurgitation, polyuria, and polydipsia. Reproductive ultrasound demonstrated several viable foetuses, and the bitch was treated conservatively. Two days later, the bitch was hospitalized due to continued hyporexia, vomiting, abdominal distention, and an acute onset of haematochezia. Blood work showed regenerative mild anaemia and neutrophilia with a left shift, metabolic acidosis, hypocalcaemia, hyponatremia, hypochloraemia, hyperkalaemia, and Na:K ratio of 24:1, raising the suspicion of an Addisonian crisis. Baseline serum cortisol on the following day was slightly above the reference interval. Due to the patient's clinical decline, dexamethasone was given, and 48 h later, on day 57 post-ovulation, a caesarean section was performed. Eleven puppies were delivered alive with Apgar scores of 8-9/10.

The bitch decompensated immediately after surgery and was hospitalized for 4 additional days with aggressive supportive care. An ACTH stimulation test 2 days after the surgery did not support Addison's disease. Despite high initial Apgar scores, only one puppy survived, and the remaining 10 puppies progressively faded. Necropsy of eight puppies confirmed pulmonary immaturity with lung development at the canalicular stage.

Clinical symptoms and laboratory derangements mimicking an Addisonian crisis should be a differential in pregnant bitches requiring intensive management. The long-term survival of newborn puppies depends on final lung maturation, which cannot be reliably induced by preterm maternal glucocorticoid administration.