Equine Lip Curling And Loss Of Appetite

My horse is raising his upper lip and has a decreased appetite. I can hear his stomach rumbling. Is he sick? He hasn't had anything new to eat other than his regular diet of fresh hay and sweet feed. He is acting as if something stinks. (Leslie Miller - Georgia)

It sounds like your horse is demonstrating the "Flehmen response", which is an involuntary response to certain scent stimuli. When detecting scents such as the presence of estrus in an animal of the same species or detecting a prey animal, the horse will demonstrate a particular type of curling of the upper lip which facilitates the transfer of pheromones and other scents into the vomeronasal organ in the roof of the mouth.

It is possible that your horse is detecting a prey animal, such as a fox or coyote nearby, or that he can smell a female in estrus in a nearby field. Either situation would be enough to make him anxious and feed less than normal. However, if your horse is not eating enough food for adequate nutrition, you must have him examined by your vet to rule out an underlying medical condition.