Clinical Disorders of Calcium in Horses: Hypercalcemia and Hypocalcemia Flashcards
(T/F) The clinical signs of hypoparathyroidism are due to decreased PTH
False, clinical signs are due to hypocalcemia
(T/F) Hypocalcemia is frequent in critically ill horses and foals
True
Acidosis falsely _____________ Ca2+
elevates
Alkalosis can lead to signs of _____________
hypocalcemia
What type of hypovitaminosis D occurs in septic foals?
Acute hypovitaminosis D
(T/F) Most C-cell adenomas in horses are functional - produce calcitonin
False, they are non-functional - DO NOT produce calcitonin
(mostly an esthetic problem)
List the Hypercalcemic disorders in horses:
- Hyperparathyroidism
- Chronic renal failure
- Cancer-HHM
- Vitamin D intoxication
What blocks electrolyte and water reabsorption inducing diuresis?
High Ca2+
What induces parathyroid cell hyperplasia and increases PTH secretion?
Hypocalcemia and/or hyperphosphatemia
List the 2 forms of Vitamin D intoxication in horses:
- Iatrogenic
- From Toxic Plants
- A paraneoplastic syndrome
- Reported in horses with lymphoma, squamous cell carcinoma (gastric, prepuce), multiple myeloma, ameloblastoma
- ↑↑ PTHrP → interacts with PTH receptors → hypercalcemia
- Clinical signs: Those of primary disease process
- Laboratory: hypercalcemia, hypophosphatemia, high. PTHrP, low PTH
- Radiographs: There could be bone loss
Hypercalcemia of Malignancy-HHM
What is the most common cause of hypercalcemia in horses?
CRF
(T/F) Hypocalcemic disorders tend to be acute, while hypercalcemic conditions tend to be chronic and carry a guarded to poor prognosis
True
What is the plan of action for Hypercalcemia – Chronic Renal Failure?
- Dietary management
- Low Ca2+ diets (e.g. no alfalfa)
- Electrolytes and water access
Why do horses and foals develop hypocalcemia?
- Impaired parathyroid gland dysfunction from cytokines
- Calcium loss in the intestine
- Intracellular sequestration of calcium
- Hypomagnesemia
- Hypovitaminosis D
