What you see. The starting point for addressing any equine health related issue is your observation.


Shivering, Muscle Trembling All Over


Shivering is usually a response to cold or wet conditions. The system works like a thermostat. Receptors signal the hypothalamus of the brain that the body's temperature is lower than the pre-set normal range. This signals the muscles to begin shivering. The purpose of the muscle vibration is to generate heat and raise body temperature. However, horses will also sometimes shiver if they have a fever, are stressed, are experiencing abdominal pain (colic), or are recovering from anesthesia. Any severe body-wide illness, pain, shock or exhaustion may also cause a horse to shiver or tremble.

  • Code Red

    Call Your Vet Immediately, Even Outside Business Hours
    • If the horse has no appetite and is obviously depressed.
    • If the results of the Whole Horse Exam (WHE) in the resting horse indicate fever (Temp>101F/38.3C), or heart rate greater than 48 BPM.
  • Code Orange

    Call Your Vet at Their First Available Office Hours
    • If the horse's appetite and attitude are normal and you see nothing else wrong.
    • If the results of the Whole Horse Exam (WHE) suggest the horse is otherwise normal.
    • If the horse has been exposed to cold or wet and this probably explains the sign.
  • Code Green

    Contact Your Vet to Obtain Useful Advice & Resources
    • To discuss your equine's general health and management.
    • Even if the horse seems normal, it is best to start the conversation.

your role


What To Do

If you can clearly attribute the problem to exposure to cold, then manage that. If a horse is cold and wet or lacks shelter, dry them off, blanket them, and/or move them to a place of greater warmth or shelter. The shivering should gradually subside. Perform the Whole Horse Exam (WHE), paying particular attention to the presence of fever, or poor appetite. Walk the horse forward and in a circle, and be sure they they move normally. Look for other signs of injury or illness. Contact your vet to discuss your findings and concerns.

In most cases, you will manage an (otherwise healthy), shivering horse without your vet seeing the horse. If you are concerned that there is more than just cold causing the trembling, then you may involve your vet.

your vet's role

Your vet's approach to this starts with an assessment of overall health using a physical exam. They look at shivering in the context of the other signs the horse is showing. Blood work can be helpful in ruling out electrolyte abnormalities that can directly lead to trembling or twitching of muscle.
Questions Your Vet Might Ask:
  • Does your horse seem normal otherwise?
  • How is your horse's attitude and appetite?
  • Is the horse wet?
  • Is the ambient air temperature very cold?
  • Is the horse doing better with more shelter or a blanket?
  • What are the results of the Whole Horse Exam (WHE)?
  • Do you notice any signs of abdominal pain (colic)?
  • What is the horse's age, sex, breed and history?
  • Is the horse an American Quarter Horse with Impressive bloodlines?
  • Was the horse recently anesthetized?
  • Has the horse been tested for HYPP?

Diagnostics Your Vet May Perform

Figuring out the cause of the problem. These are tests or procedures used by your vet to determine what’s wrong.

Very Common
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Diagnoses Your Vet May Consider

The cause of the problem. These are conditions or ailments that are the cause of the observations you make.

Very Common
Less Common
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Treatments Your Vet May Recommend

A way to resolve the condition or diagnosis. Resolving the underlying cause or treating the signs of disease (symptomatic treatment)

Very Common
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further reading & resources

Author: Doug Thal DVM Dipl. ABVP