Hypocalcemic Tetany in Horses

Nature of Disease: An uncommon condition caused by the acute depletion of serum-ionized calcium.
Primary Causes:
- Lactation: High milk production in mares, often predisposed by grazing on lush pastures.
- Transport: Stress and lack of calcium intake during travel.
- Physical Exertion: Prolonged activity (e.g., endurance rides) leads to calcium loss through sweat.

Secondary Causes:
- Toxins: Blister beetle ingestion.
- Medications: Administration of bisphosphonates.
- Physiological Stress: High corticosteroid levels from stress inhibit Vitamin D, decreasing intestinal absorption and skeletal mobilization of calcium.

Neuromuscular Signs:
- Increased excitability, muscle tremors, and stiffness of gait.
- Tetany: Including trismus (lockjaw), inability to chew, and prolapse of the third eyelid.
- Severe cases: Recumbency and convulsions.
Gastrointestinal Signs: Decreased intestinal motility leading to colic signs.
Distinctive Sign: Synchronous diaphragmatic flutter.
Cardiac Signs: Arrhythmias and increased intensity of heart sounds.

Tentative Diagnosis: Based on history, clinical signs, and rapid response to treatment.
Definitive Diagnosis: Demonstration of low serum levels of ionized calcium.
Diagnostic Challenges: Total serum calcium may appear normal in alkalotic horses even if they are symptomatic; conversely, acidotic or hypoalbuminemic horses may have low total calcium without showing signs.
Differential Diagnoses: Must be distinguished from tetanus, botulism, colic, exertional rhabdomyolysis, and seizure disorders.

Emergency Care: Slow intravenous (IV) administration of calcium solutions (e.g., 20% calcium borogluconate).
Monitoring: The cardiovascular response must be closely watched; infusion should stop if bradycardia or arrhythmias develop.
Supportive Care: Providing high-quality forage like alfalfa.
Prognosis: Usually leads to full recovery, though some horses require repeated treatments over several days.

Dietary Management: Provide balanced rations with proper calcium-to-phosphorus ratios during gestation.
During Peak Demand: Supply high-quality forage (alfalfa) and avoid fasting during lactation or transport.
Exertion Management: Ensure sufficient water and electrolyte supplementation for endurance horses.
Pharmacological Caution: Use bisphosphonates with extreme caution in horses with existing electrolyte imbalances or renal disease.

Page updated

Google Sites

Report abuse