Severe hypercalcaemia in dogs: emergency treatment
7-year-old Labrador with polyuria, polydipsia, vomiting and weakness; 7% dehydrated. Total calcium 17.2 mg/dL, ionised calcium 2.1 mmol/L and creatinine 2.4 mg/dL. The cause has not yet been found.
What is the most appropriate initial treatment?
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A. Prednisolone immediately, because it is the drug that lowers calcium most
If the cause is lymphoma, corticosteroids can mask the diagnosis (cytology, imaging) and promote chemotherapy resistance. They are reserved until it has been ruled out or confirmed.
B. IV furosemide from the start to increase calciuresis
The dog is dehydrated: a diuretic before rehydration worsens volume status and kidney injury. Furosemide is added once volume is restored.
C. Oral hydrochlorothiazide to protect the kidney
Thiazides reduce renal calcium excretion and worsen hypercalcaemia: they are contraindicated.
D. 0.9% saline to rehydrate and maintain diuresis, furosemide once volume is restored, and a search for the cause before giving corticosteroids
Correct. Saline corrects dehydration and its sodium promotes renal calcium excretion. Meanwhile, look for the cause: rectal exam, lymph nodes, thoracic radiographs, ultrasound and cytology. If it persists, add a bisphosphonate.
lightbulb Key takeaway
Hypercalcaemia with normal or high phosphorus damages the kidney through mineralisation: a calcium × phosphorus product above 70 (in mg/dL) greatly increases the risk. Treat the emergency and look for the cause at the same time.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.