Horse Side Vet Guide ®

Equine Health Resource

Lip Quivering, Lip Flapping, Strange Movement of Lips

Code Red - Call Your Vet Immediately, Even Outside Business Hours

Code Orange - Call Your Vet at Their First Available Office Hours

Code Red - Call Your Vet Immediately, Even Outside Business Hours

  • 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.
  • If the horse seems to be having difficulty eating, in addition to showing this sign.

Code Orange - Call Your Vet at Their First Available Office Hours

  • If the behavior continues with no explanation.
  • 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.

Some horses make strange lip movements seemingly just for fun. However, lip movements can also be indicative of a wide variety of emotional states and can even signal a physical problem.

Like lip curl (Flehmen Response), a variety of other lip movements can be considered normal behavior or can be a sign of a physical pain, or anxiety or irritation.

Lip twitching and trembling can be related or unrelated to eating. Occasionally, a horse’s lips will move in a strange or inappropriate way when they are offered feed. These horses may also not be able to properly grasp feed with their lips and move it back in the mouth. This is a classic finding in horses with Yellow Star Thistle or Russian Knapweed poisoning.

Foreign objects embedded in the mouth and dental issues can cause strange lip movements out of discomfort.

Lip twitching and flapping are common after a horse has been given an oral medication or de-wormer. The lip curl (Flehmen response) is a natural gesture when a horse is presented with a new smell, and is common in breeding stallions around mares. I wrote another record dedicated to the lip curl.

Some horses flap their lips loudly when they are nervous or anxious, or anticipating an undesirable event.

Recognize that a variety of lip movements can be considered normal, but that they might also signal anxiety or even a physical problem.


Carefully observe the horse for a few minutes before making any assumptions about what is going on. Is this trembling, smacking, or something else. Take a video and share with your vet.

Consider the context. When is this occurring? Is it under saddle, when fed, or when simply resting.

When horses twitch or flap their lips under saddle, it can indicate stress. Consider the factors that might be causing anxiety or irritability, and adjust your approach accordingly.

If the lips movements are occurring when the horse is fed, determine whether or not the horse can properly eat. Assess your horse’s general health using the Whole Horse Exam (WHE) paying particular attention to how the horse moves at the walk, and their attitude and appetite, heart rate and rectal temperature. Assess the mouth (wear gloves), and look at the inside and outside of the lips and look in the nostrils. Offer feed and water and determine whether they are interested in feed and can chew and swallow. Look carefully for trembling elsewhere on the body. Contact your vet with your findings and concerns.


Your vet will assess the behavior to determine whether or not it is normal for the horse. They will perform a physical exam, paying particular attention to the mouth and neurologic system. Depending on the characteristics of the behavior, they may want to rule out intestinal conditions causing colic.

POSSIBLE TREATMENTS or TherapiesTo Lessen or Resolve the Sign

Author: Doug Thal DVM Dipl. ABVP


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