Sunday, March 29, 2009

A pain in the horse: Signs your horse is hurting

The Horse magazine's published an article on detecting pain in horses which they highlighted in their Lameness Report recently. Studies show that horses are much more stoic than we realize. From an evolutionary standpoint, the ability to mask pain has survival value, since predators can't easily pick out the compromised animal in the herd. Horses can't tell us when they're in pain, and unfortunately there are no physiological responses that can be attributed specifically/only to pain. Horse owners are left with the task of looking for subtle behavioral signs. Here is the The Horse magazine's list of signs a horse might be in discomfort (from The Horse article):

  • head at wither height
  • ears out
  • trying not to move
  • glazed eyes
  • elevated heart rate
Other articles mention depression or sedentary attitude, reduction in self-maintenance behaviors (eating/drinking), "guarding" and attraction to the painful area, stamping, pawing, and of course some of the classic colic signs like sweating, biting sides, etc.

Kinds of pain
Lots of articles classify equine pain along different dimensions: acute/chronic, systemic vs. localized, etc. I'll let you read those yourself since they're tough to summarize. But I love little factoids like these...
  • Years ago I read in Equus Magazine that horses experience pain differently than humans. I think the authors tried to make a case that because horses are flight animals, lameness somehow doesn't hurt as much. Personally I was skeptical, but it's an interesting thing to contemplate.
  • Another article said that horses are especially sensitive to internal pain, and that's why the signs of colic are fairly obvious (horses can't mask the pain as easily).
  • Muscular pain is most likely to result in aggression. "Aggression" is loosely defined but I think it refers to bucking under saddle, "air biting" when you tighten the girth, etc.

Cortisol in the blood

High cortisol levels in the blood are a possible sign of pain according to The Horse. Other sources, such as a Purdue extension publication, pointed out that cortisol is not a specific indicator of pain -- levels go up during periods of excitement, exercise, stress, or pleasure (e.g., mating). Cortisol fluctuates during the day and is elevated in the morning. Purdue veterinary experts suggest that repeated blood samples over time are needed before drawing any conclusions. For most owners, this is impractical.

How is cortisol related to pain? Cortisol is a hormone that initially increases glucose, which provides energy for “flight.". While this effect of cortisol is beneficial at the onset of a stressful situation, cortisol ultimately decreases the uptake of glucose into the cell.

Some pain is good
Years ago an older lady at a barn were I boarded complained that her mare was more difficult to handle after her Legend injections. "She moves better, but now she's full of piss and vinegar, and she's bucking under saddle," the lady told her trainer. Her trainer paused for a moment. "Well, then let's keep her sore. " That was the end of the Legend injections. While we like our horses be comfortable, trying to eliminate pain entirely is probably a mistake. Pain forces the animal to rest and guard it's body, which allows tissue to repair itself.

The Horse article states that "The absence of normal behavior is the most striking sign of pain in animals....any abnormal posture, movement, expression, attitude, or behavior is a potential sign of pain." This strikes me as a pretty good take home message.


Understanding equine pain from The Horse Magazine

Detecting pain from The Horse Magazine v. 8 (3)

Masters of Disguise from The Natural Horse

International Veterinary Academy of Pain Management

Assessing the well-being of horses from Purdue University

Recognizing pain in horses from Michigan State U

Exploring the perception and physiology of pain in horses from DVM News

New research boosts understanding of pain from Horse and Hound


  1. "While we like our horses be comfortable, trying to eliminate pain entirely is probably a mistake. Pain forces the animal to rest and guard it's body, which allows tissue to repair itself."

    This is why injecting race horses with painkillers is bad. They don't get the signal from their body to stop putting weight on something and soon you have a catastrophic breakdown. (soap box...sorry)

    You can't tell a horse, "now, don't use that..." and then take the pain away and expect them to not use their injured part.

  2. Good information - thanks for researching that!

  3. Thank you for the good information - this just emphasizes to me how important it is for each of us (and others who are handling/feeding) to know each horse as an individual and to know what their "normal" behavior is. Pain indications can also be very subtle - we have one mare who gets wrinkles in her muzzle just above the lips!

  4. Wonderful article. Thank you! I take care of a draft horse with white line, who is prone to seasonal hoof abscesses. They must be incredibly painful. hard hoof, no place for the pressure to release.

    He's very stoic, but at the beginning of an abscess, he'll try to let you know it hurts by walking on legs 1, 2, & 3 normally, then #4 is hoisted in the air and he stops to pointedly stare at it.

    He'll make sure you 'get' it, and will stand quietly through the pain of treatment, and walk back as normally as possible.

    I believe horses feel pain as intensely as people do. Hogwash to "it doesn't hurt them as much".

    Kudos for a great article.

  5. An Australian vet is teaching people to manage pain in their horses with amazing results. His approach is a form of acupuncture that uses red light (a torch). It is called Photonic Therapy


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