The flehmen response in horses – what does that curled upper lip mean?


The typical flehmen response in horses also includes raising and stretching the neck while curling the upper lip and exposing the teeth.  It can mean one of a few things, mostly good, but one is a sign of distress.  Cats, horses, rhinos, and even hedgehogs have this response.


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The flehmen response mainly helps with your horse’s sense of smell.


  • The flehmen response interacts with the vomeronasal organ near the palate to amplify smells. Those smells are usually horse-related smells, like manure and urine, but also include other novel smells that your horse may find while cruising around doing horse things. Fancy, right?


horse pink nose doing flehmen response

Not a horse to hide his feelings about wormers, this is the flehmen response after a dose.


  • In horses, stallions exhibit this behavior quite a bit, especially around the ladies.


  • Mares will often demonstrate the flehmen response after giving birth or while in season. 


  • Geldings are the group of horses that rarely demonstrate the flehmen response, but you will still find they will. I have known horses obsessed with other horse’s manure, in the paddocks, in the ring, in the cross tie bins, and will regularly display the flehmen response.


  • Other horses do so after eating something horrible (like a wormer) or even if they are looking for the right spot to roll in the field.



horse flipping upper lip in flehmen response

The flehmen response, complete with extended and lifted head and neck.


A sign of colic


  • Most horses will also display the flehmen response when in pain, usually with abdominal pain – like colic.


  • I have seen horses in pain do this, and they may not raise their heads and necks, so all you see is the upper lip curling or twitching.


  • Other horses in pain might also show the flehmen response and lift their heads and necks.


  • It’s your job to determine if your horse’s lips tell you about pain. Other signs of pain in a horse have increased heart rate and/or an increase in respiration. You know, his vital signs. This article teaches you how to find your horse’s vital signs. If you see this flehmen response and it seems out of the ordinary, take your horse’s vital signs and call the vet.




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