Canine Hypoparathyroidism Study Guide

Overview and Clinical Importance

Hypoparathyroidism is an uncommon but clinically significant endocrine disorder in dogs characterized by deficient or absent secretion of parathyroid hormone (PTH) from the parathyroid glands. This deficiency results in hypocalcemia (low blood calcium) and hyperphosphatemia (elevated blood phosphorus), leading to potentially life-threatening neuromuscular and cardiovascular complications.

While hypoparathyroidism is relatively rare, it represents an important differential diagnosis for any dog presenting with neuromuscular signs such as tremors, tetany, or seizures. Early recognition and appropriate treatment are essential, as untreated hypocalcemia can be fatal. The condition is highly manageable with lifelong therapy, and affected dogs can achieve a normal quality of life with proper monitoring.

Pathophysiology

Calcium Homeostasis

Calcium plays an essential role in numerous physiological processes including neuromuscular transmission, muscle contraction, blood coagulation, enzyme activation, and bone formation. Approximately 99% of body calcium is stored in bone, with only 1% in soft tissue and blood. Of circulating calcium, about 50% is ionized (free) and biologically active, 40% is bound to proteins (primarily albumin), and 10% is complexed with anions.