Horses in pain: Experts identify facial indicators

| 3 August 2013 4:47 pm
No laughing matter: Experts have successfully identified facial expressions in horses indicative of pain.

No laughing matter: Experts have successfully identified facial expressions in horses indicative of pain.

A horse walks into a bar and the barman says, “Hey buddy, why the long face?”

It may be the oldest horse joke in the book, but researchers are making serious progress in deciphering the facial expressions of horses.

Experts have developed a new standardized scale of facial expressions to help horse managers discern pain.

Through the results of a recent study, researchers from Italy, Germany and Britain have developed what they are describing as the standardized Horse Grimace Scale (HGS) to assist in pain detection in horses.

Dr Michela Minero, who presented the research group’s findings at the recent 2013 annual conference of the International Society for Equitation Science in the United States, said the scale could assist the welfare of horses who have undergone routine surgical procedures such as castration.

“The standardized HGS is easily trainable to laypersons and may be beneficial to those in the position of managing horses that have undergone painful procedures,” Minero said.

Only a minority of horses undergoing routine castration in Europe receive postoperative pain control, even though the procedure is known to be painful.

“Annually, it is estimated that 240,000 horses are castrated in Europe, and castration has been shown to be associated with a certain degree of pain,” Minero says.

“However, only about 36.9 percent of horses receive analgesics for post-operative pain. One of the possible explanations for this is that the assessment of pain in horses undergoing castration is still sub-optimal.”

Forty-six stallions of varying breeds, ranging in age from 1-5 years, were used in the study.

The horses were divided into one of two treatment groups and a control group. Treated horses underwent routine surgical castration using the closed technique.

Group A, comprising 19 horses, received one injection of Flunixin-Meglumine, commonly known as Banamine immediately prior to anaesthesia, while group B, made up of 21 horses, received the same drug both prior to anaesthesia and six hours post-operatively.

A control group of six horses requiring non-invasive diagnostic procedures under general anaesthesia were also used in the study.

All of the horses studied were hospitalized for five days. As a baseline, high definition videos of the horses were taken both for 30 minutes on the day prior to surgery, and eight hours post-operatively. Video recording continued over the five-day period, from which high quality images of the horses’ faces were extracted.

These images were then scored by five treatment-blind observers.

Subtle changes in facial expressions/changes indicative of communicating pain have been identified in other species, and the researchers hoped to be able to standardize such expressions in horses.

One complicating factor affecting assessment could be how and when the horse chooses to express pain.

Minero continues: “Because there is no verbal means of communication between animals and humans … this could be further compounded by the horse’s suppression in the expression of obvious signs of pain when in the presence of humans.”

The facial actions chosen to identify pain included: stiffly backward ears, orbital tightening, tension above the eye, strained chewing muscles, mouth strained and pronounced chin, strained nostrils, and flattening of the profile.

A treatment-blind observer, experienced in facial expression assessment in other species, reviewed the images to identify facial expression changes in the horses.

Pain-related behaviours occurred predominantly eight hours after the operation, suggesting this was a critical time for pain evaluation.

The results of the study showed both a high degree of accuracy (73.3 percent) in pain assessment, and a high level of inter-observer reliability.

The findings suggest that such a scale could indeed benefit those in the position of managing horses that have undergone painful procedures.

The researchers noted that darker coloured horses were harder to score than lighter ones.


Category: Health, Research

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Comments (16)

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  1. Laura Murry says:

    a link to the pictures would be good.

    Very educational for a lot of people who can’t ‘read’ animals very well.

  2. Barbara ODay says:

    I agree with Laura, pictures showing exactly these points would be of great help!!

    • Fritha Langford says:

      HI Laura and Barbara,
      This work was carried out as part of the Animal Welfare Indicators project. The science detailed above will hopefully be published in the scientific press in the next couple of months. As soon as that happens, we have a variety of learning materials that will be released on the Animal Welfare Science Hub ( which will not only have photos but also training to help horse owners and others recognise pain in horses by their faces. There will be an App on this too. Thanks for your interest.

  3. Zig Pope says:

    My brother is a vet. He constantly reminds us humans, that ALL MAMMALs, of which we are one, are exactly the same physiologically. When we cut ourselves, and dogs or horses or cats, cut themselves, we are all feeling the same kind of pain.

    If we are flying in small airplanes over 12000 feet and need oxygen! So do our pets in the airplane.

    I could never understand why pain control was not used in animals or why humans thought animals did not suffer pain.

    • Marlies de Vries-Meijer says:

      That’s so true! You don’t have to be a vet to know this. Only heartless ppl hurt others. There ought to be a worldwide law for animal protection with havier punishment. Enough is enough!

  4. Shannon says:

    I had two horses gelded in the past and both received Banamine for pain. It’s idiotic to assume just because they can’t cry that they don’t feel pain. They have nerve endings just like we do :-)

  5. Melanie Rowley says:

    If anyone wants to see pictures showing pain in a horse’s face?

    Go look up Big Lick, Speed Racking horses, or Rollkur.

    Pretty easy to see the pain in those horse’s faces.

    And always amazes me people can’t also see confusion and sorrow in their eyes too. Or the quite despair when they know things will only get worse.

    And no, I am not of the “poor horsey be free” mindset at all, but do know that the horses are saying many things about how they are treated.

    • Karme says:

      Estoy de acuerdo. Solo hay que observarlos, pero eso requiere disponibilidad de tiempo. Solo hay una manera de aprenderlo. Observando cuando estan bien y cuando no. Cuando se estan “exhibiendo”, cuando estan relajados, cuando estan enojados, cuando estan cansados, cuando estan jugando, cuando estan soñando, cuando estan durmiendo,cuando estan asustados, etc…
      mal vamos si nos tienen que enseñar cómo es la expresión del dolor en la cara de un caballo.
      Nadie ha visto a un caballo apretar las mandíbulas cuando siente dolor? nadie ha observado cómo sus músculos faciales se ponen en tensión? cómo remarcan el arco de sus cejas? nadie ha observado sus caras en un proceso de cólico? incluso cómo cambian la cara después de ser tratado el dolor? Fijaos si podeis sacar material fotográfico antes y después de cualquier dolencia.

    • Morgan says:

      I would like preface this statement with the acknowledgement that not everyone in the gaited communitiy does this.
      However, there are a lot of horrible things that happen at gaited horse shows. You may or may not have heard of soaring. While the rules and regulations on this disgusting treatment of horses are getting better, ex: soaring is now a felony in the state of TN, it still happens. Soaring includes using chemicals/chemical burns on the horses legs, as well as putting objecting inbetween the sole of the hoof and the shoe before railing it in, and other practices to “teach” horses to rack in a more animated fashion. Unfortuantely it can be extremely hard to catch or prove this abuse has been practiced. I, personally, have never seen as much pain on a horses face, as a horse at a racking show.

  6. Paula says:

    It would be educational to show the photos.

  7. Caitlin says:

    It amazes me that people got paid to “study” this. Anyone who has spent a significant amount of time around these animals already knows these looks.

    Why not go around schooling barns and ask responsible, experienced owners and handlers how they know when their horse is in pain or ill? They could have told you these expressions – at least I know I could have.

    • Patagonia Trails says:

      Hi. I agree with your point of view, the idea of having a scale and “officially” be open about the idea that the horses do have facial expression when they suffer or are in pain is going to help many horses to and humans to understand each other better. To learn more.
      Cheers from Patagonia.

    • Miles says:

      Here here

    • Marlies de Vries-Meijer says:

      If ppl didn’t hurt animals, this would have never been an issue. Education first begins at home. If you’re good to animals, your children will also. Animalcruelty is a shame on humanity.

  8. MinakoSargent Fukuda says:

    if you watch even while you brush your horse you can observe if he/she flinches,they also show if they miss you,I cant go visit mine because someone killed my car,but he is ok,being loved by the ones who originally had him anyway,so I am very lucky,but was told he misses me,dont know how they show it,what really gives me the irits is when they shoot from helicopters and do not go down to check if they are dead and leave them to die in agony,this is still going on,I just got told yesterday!we complain about cruelty in other countries ,how about here right at our doorstep!

  9. Laura Martin says:

    Could you download and post a link to some of the video footage. This would be most helpful for ALL horse owners to be aware of.

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