(synchronous diaphragmatic flutter)
Definition: spasmodic contraction of the diaphragm in time to the heartbeat
Causes: depletion of calcium ions in the body fluids,
resulting from endurance work or other activity that entails long-term sweating without the opportunity to recover
Signs: rhythmic twitching of the flank muscles in time with the heartbeat, usually at least 50 times per minute. In some cases, the thumping may be audible.
Diagnosis: observation of signs
Treatment: Stop work and allow the horse to graze and drink. An electrolyte supplement may be helpful. Use your cell phone or another device to take video of your horse to help confirm the diagnosis, in case it stops before the veterinarian gets there. Your veterinarian may choose to administer intravenous calcium. If the horse is also showing signs of dehydration, fever, loss of appetite and is weak and unresponsive, he may be developing heat exhaustion—take immediate steps to cool him off, and seek veterinary care.