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Do horses grieve?

Posted: Monday, October 02, 2006

Emotions long thought to exist only in humans actually may influence unusual behavior in horses

by Kenneth L. Marcella, D.V.M.

Tony and Pops were the best of friends and had known each other for years. They had worked together long ago and had since moved to the same place together. Their days now were the slow and easy routine of retirement, and neighbors often remarked that you would never see Pops out walking or perhaps eating without Tony right there with him.

But recently, Pops had begun to feel poorly, and the news from his doctor was not good. Pops continued to decline. Then one day, with Tony still by his side, he passed away.

Tony was devastated. He became uninterested in food and began to lose weight. He stopped interacting with those around him and became severely withdrawn. Without Pops there, Tony quit going for walks or moving around much. Lack of activity began to affect his body, and he lost muscle and conditioning. His arthritis, which until the death of his friend had been fairly well controlled, became worse. Losing weight sapped his energy and weakened his immune system. He developed some respiratory problems, started to become anemic, and was rapidly going downhill.

Tony was showing all the signs of physical and psychological depression.

This is a very common scenario; the loss of a family member, loved one, or close friend can be a significantly stressful event for people, especially the elderly. But Tony and Pops were equine buddies, and the increasing longevity of horses seen over the past decade is making situations like this even more common. More horses are spending significant time together, sometimes ten years or more, making the death of a herd mate a significant event for the surviving horse.

Claudia Barton, D.V.M., a cancer specialist at Texas A&M University, deals with death, loss, and grieving in the course of her daily work.

"Outside of some anecdotal and observational information concerning elephants, there is almost nothing written on the subject of animal-animal loss," Barton said.

The lack of documentation on grief in animals may be because grief is exceptionally difficult to quantify and therefore difficult to study. "Environmental and habitual changes that occur routinely in animals' lives may alter their behaviors and make the evaluation of true grief even more difficult," Barton said.

Grief in human terms

Veterinarians have come to see the effects of a pet's passing as so potentially important to their clients that numerous veterinary schools and private practices now employ grief counselors. Still, the issue of loss receives little scientific attention when it concerns a horse reacting to the death of a close partner or herd mate. Some researchers imply that imparting human feelings and emotions to animals (anthropomorphism) is inappropriate. But owners, trainers, and others who spend considerable time with horses disagree. They feel they can recognize in horses emotions usually reserved for humans. Most veterinarians also recognize these behavioral expressions in animals.

In our example of Pops and Tony, most veterinarians would recognize Tony's behavior as the classic presentation of depression, and most horse owners would say he acts sad. Some scientists and behaviorists agree, and they feel there is more science to the way animals act.

Identifying emotions

Sharon Crowell-Davis, D.V.M., Ph.D., a board-certified animal behaviorist at the University of Georgia, is certain these interpretive evaluations of how animals feel in response to specific situations are fairly accurate. She also has the science to prove it.

"The use of PET [positron emission tomography] scans provides researchers with an evaluation of mental states based on brain activity and neurochemical changes noted in response to specific stimuli," she said.

When undergoing a PET scan, a person is presented with a stimulus that causes a particular emotion. Pictures, smells, and sounds can be used as stimuli. If a person is shown a picture that incites anger, for instance, the PET scan records the person's brain activity and the chemical changes that occur following that stimulus.

"When animals are recorded showing the same patterns of brain activity and the same brain chemical changes that correspond to a particular human emotion or mood state, it would not be logical for us to assume that they are not experiencing similar feelings," Crowell-Davis said. Based on this thinking and on how closely the reactions of some horses correspond to the classical signs of clinical depression with very intense individual responses, the loss of a close companion is now believed to be felt as sadness by some horses and recognized as an expression of grief.

Abstract concept

A lack of information as to how animals interpret or understand the concept of death exists. Again, many owners, trainers, and veterinarians feel animals exhibit some primitive form of comprehension. As in humans, the response to death is individualistic; when one of a pair of horses dies, the remaining horse may show little to no response or may be profoundly affected and extremely reactive.

Katherine Houpt, V.M.D., Ph.D., physiologist and director of the Animal Behavior Clinic at Cornell University's College of Veterinary Medicine, acknowledges that there is tremendous variation in the amount of attachment shown by individual horses. Some "loner" horses never seem to join up with the herd, and other horses bond to almost any other horse after only a short trailer trip or trail ride.

"Some horses tend to form stronger and more numerous friendships, and a specific horse may be extremely bonded to one other horse and yet exhibit no concern for other horses in the same group," Houpt said.

Equine maternal behavior has been better studied and tends to follow this pattern of variability, as well. When a young foal dies, the mare may show a strong response with vocalization, anxiety, and agitated behavior. Another mare may show only mild concern to little interest in the deceased foal. Veterinarians recommend allowing the mare to spend time with her dead foal. Most mares will examine the foal, move away, return, and move away again. Depending on the individual, this process may continue for some time, but eventually the mare will begin to ignore the foal, and it can be removed.

The same process also is recommended for surviving herd mates. It is interesting to watch how closely some horses will stay to a dead companion, often standing over it or even lying down near it, while others will act agitated or frightened by the dead body and may not even approach it. This variability may approach the many different ways that humans deal with death and loss. But horses given the opportunity to interact with a dead pasture mate generally show less vocalization and anxiety and return to normal behavior more quickly.

"They grieve and, as far as we can tell at this point, they come to some realization of death," Crowell-Davis said.

Helping horses cope

Some horses, such as Tony, show an exaggerated grief response even if given the opportunity to interact with a dead pasture mate. The expression of intense depression can be present with physical problems that are psychologically based. Affected horses are restless, anxious, or withdrawn, and they often show sleeping or eating irregularities. They may stop normal activity, or they may spend all their time calling and searching for the lost companion.

The appropriate treatment for these horses is similar to that used for depression in humans: Supportive therapy should be directed at any medical problems that may worsen with depression. Arthritis, muscle loss, and decreased water and food intake are the main problems. Treatment is aimed at getting the horse interested in its environment again. Increased attention, treats or special foods, and increased play and interaction all can be tried. Something as simple as grooming may be beneficial with some horses.

Many owners want to try to introduce another horse to the situation in hopes that the depressed horse will bond and be helped. This approach will fail as often as it will succeed. Some horses, especially older horses, may resent a new addition, so more stress is created by the introduction.

Houpt recommended trying to introduce a new horse before one of a pair of older horses becomes ill. A pre-existing bond with such a new horse may help the remaining horse deal with loss. Many owners and trainers will be able to identify this universally acceptable herd mate on their farm--a horse that seems to fit comfortably and calmly into any group--and this is the ideal horse for such a situation.

Drug options

For some horses, medical management of depression is needed, especially for horses that show such severe grief that they are in danger of colic, anemia, dehydration, or other metabolic concerns that are made worse by depression. The first choice for treatment is diazepam (Valium), which can reduce anxiety and stimulate appetite. This drug produces the quick effect that is needed in these cases. Fluoxetine hydrochloride (Prozac) is used for long-term maintenance. This combination of Valium followed by Prozac has been quite helpful in reducing the effects of grief in horses. Methylphenidate (Ritalin) also has been tried, but the results are not as rewarding.

Once horses return to more normal activity patterns, the dose of Prozac can be gradually reduced and eventually discontinued.