Parathyroidectomy

Persistently elevated blood calcium (hypercalcemia) damages the kidneys, causes bladder stones, and in severe cases leads to lethargy, weakness, and neurological signs. Surgery is recommended when:

• A parathyroid adenoma (benign tumor) has been identified as the cause of elevated calcium and PTH on blood testing
• Ultrasound has localized one or more enlarged glands in the neck
• Medical management with IV fluids or bisphosphonate drugs has been used as a bridge but is not a long-term cure

Unlike some parathyroid tumors in humans, the vast majority of canine cases involve a single benign adenoma — removing it is curative. Carcinoma (malignant parathyroid tumor) is rare but managed surgically when possible.

Parathyroidectomy is performed under general anesthesia. The steps:

• A ventral neck incision (similar to thyroid surgery) provides access to the parathyroid gland region
• All four parathyroid glands are identified and inspected; the enlarged, abnormal gland(s) are removed while the remaining glands are preserved
• Intraoperative PTH measurement — a rapid blood test done during surgery — may be used at referral centers to confirm that PTH drops immediately after removal, verifying the correct gland was excised
• The incision is closed in layers; surgery typically takes one to two hours

Ultrasound-guided minimally invasive ablation (heat or chemical destruction) is an alternative to open surgery for carefully selected patients; your surgeon will discuss whether it applies to your pet's case.

The diagnosis is confirmed through a combination of repeated serum calcium measurements, a PTH assay, and neck ultrasound to identify and localize the enlarged gland. Pre-anesthetic bloodwork assesses kidney function — which may be compromised by chronic hypercalcemia — and guides fluid therapy planning. Severely hypercalcemic patients often receive IV fluids before surgery to protect the kidneys. Withhold food from the evening before the procedure; water is generally permitted until a few hours prior.

The most important post-operative concern is hypocalcemia (low calcium). After the adenoma is removed, PTH levels drop sharply and the remaining, suppressed parathyroid glands may take days to weeks to resume normal function. During this period:

• Blood calcium is monitored closely for 24 to 72 hours in hospital
• Oral calcium supplementation and, in some cases, vitamin D (calcitriol) are started prophylactically
• Owners should watch at home for signs of low calcium — facial twitching, muscle spasms, or unusual weakness — and call immediately if they appear
• Follow-up calcium checks are scheduled at one week, one month, and three months post-operatively
• An Elizabethan collar protects the incision until sutures are removed at 10 to 14 days

Parathyroidectomy carries a high success rate when the correct gland is removed. The principal risks are:

• Post-operative hypocalcemia: the most common complication; usually temporary and manageable with supplementation, but requires diligent monitoring
• Recurrent laryngeal nerve injury: an uncommon risk shared with thyroid surgery that may affect voice or swallowing
• Persistent or recurrent hypercalcemia: may occur if multiple adenomas were present and one was missed, or if a malignant tumor has spread; follow-up calcium checks detect this early

In experienced hands with appropriate post-operative monitoring, the large majority of patients resolve their hypercalcemia and return to a comfortable, normal quality of life.