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Archive Case #211: Equine Synchronous Diaphragmatic Flutter

Horse veterinary case - Easy - September 30, 2026

Clinical Clues

  1. After a long ride on a hot day, Rowan’s handler notices regular jerking movements in the mare’s flank.
  2. Rowan has sweated heavily and is dehydrated, but remains alert.
  3. The movements continue while she stands quietly and do not follow the rhythm of her breathing.
  4. On closer examination, every flank jerk occurs at exactly the same time as a heartbeat.
  5. Blood testing shows low ionised calcium and chloride, alongside metabolic alkalosis.
  6. The veterinarian identifies rhythmic diaphragmatic contractions synchronised with cardiac activity—the characteristic movement commonly called “thumps”.

Diagnosis

Equine Synchronous Diaphragmatic Flutter

The heartbeat-synchronised diaphragm movement is the decisive clue. Electrolyte and acid–base disturbances can increase phrenic nerve excitability, allowing cardiac electrical activity to trigger diaphragmatic contractions. Heavy sweating is relevant context, not a diagnosis by itself. Remember: Notice the rhythm: the diaphragm is following the heart, not the breaths. Investigate the underlying metabolic disturbance.

Learning review

Review the case evidence

Use the paired clues to explain how the evidence in this horse case supports the provided diagnosis, Equine Synchronous Diaphragmatic Flutter, then compare your reasoning with the case explanation.

Evidence checkpoints

Clues 1-2

  1. Clue 1: After a long ride on a hot day, Rowan’s handler notices regular jerking movements in the mare’s flank.
  2. Clue 2: Rowan has sweated heavily and is dehydrated, but remains alert.

Clues 3-4

  1. Clue 3: The movements continue while she stands quietly and do not follow the rhythm of her breathing.
  2. Clue 4: On closer examination, every flank jerk occurs at exactly the same time as a heartbeat.

Clues 5-6

  1. Clue 5: Blood testing shows low ionised calcium and chloride, alongside metabolic alkalosis.
  2. Clue 6: The veterinarian identifies rhythmic diaphragmatic contractions synchronised with cardiac activity—the characteristic movement commonly called “thumps”.

Self-review prompts

  1. After clues 1-2, what evidence from this horse case shaped your initial interpretation?
  2. When you compare clues 3-4 with clues 1-2, what changed in your reasoning about Equine Synchronous Diaphragmatic Flutter?
  3. How do clues 5-6 align with the case explanation for Equine Synchronous Diaphragmatic Flutter?

Educational Use

Vetdle archive cases are educational veterinary games for diagnostic reasoning practice. They do not provide veterinary advice, diagnosis, treatment, or professional medical guidance.