Silent suffering

Silent suffering
AVMA Animal Welfare Forum addresses pain management in animals

"The scientific evidence is overwhelming that animals do feel pain," said Dr. Sheilah A. Robertson, opening speaker at the 2001 AVMA Animal Welfare Forum, held Oct. 14 in Chicago. "What we need to do is now move on and discuss the more important topics like how can we help them."

This year's forum dealt with pain management in animals. Attending were 170 people, mostly veterinarians, and some veterinary technicians and students. AVMA president-elect, Dr. Joe M. Howell, opened the daylong meeting.

An associate professor in the large animal clinical sciences department at the University of Florida College of Veterinary Medicine, Dr. Robertson set the stage with an overview of pain: what it is, why to address it, how to recognize it, and ways to treat it. Later in the day, she lectured about pain management in laboratory animals. She is also a diplomate of the American College of Veterinary Anesthesiologists.

Pain, as defined by the International Association for the Study of Pain, is "an unpleasant, sensory, emotional experience associated with actual or potential tissue damage or described in terms of such damage." Yet the exclusivity of pain to the suffering individual makes it extremely difficult to accurately communicate the experience of pain. The job of the health care provider is further complicated when dealing with nonverbal patients such as infants and animals.

Pain has skyrocketed as a major health issue in the United States. An estimated 50 million people suffer from chronic pain, Dr. Robertson said. The human health care community has taken note, implementing standards for grading and alleviating pain. Meanwhile, the number of pain specialists and hospices has grown exponentially.

When it comes to animals, between 17 and 20 million animals are used in research annually in the United States, most of those being rodents. Dr. Robertson estimates there are at least 20 million dogs, 60 million cats, another 60 million feral cats, and an undetermined number of farm animals are exposed to painful procedures in the United States. At least 20 percent of dogs in this country suffer from osteoarthritis, she added.

And although animals may not experience pain exactly the same way humans do, that does not detract from an ethical responsibility to alleviate animal suffering, Dr. Robertson said, referencing the recently adopted AVMA position statement on pain management.

Pain itself is different from the process in which unpleasant stimuli are transmitted to the spinal cord, which is the task of nociceptors and nerves. These receptors, incidentally, are found in humans and other animals, and have also been identified in reptiles and lower species.

To experience pain, an animal must have a functional brain and be conscious. If an animal is unconscious, as when a research animal is undergoing a procedure and never regains consciousness, for example, it cannot perceive pain, Dr. Robertson explained. "Pain [occurs] if you're aware, have a functional brain, and receive those incoming messages," she said. "So pain is always a personal experience. It's unique to each individual person and each individual animal."

Individual responses to pain vary considerably, with genetics and experience likely influencing pain tolerance. Veterinarians are at a disadvantage because their patients cannot express where the pain is and what it feels like, or even whether analgesics are working. Identifying pain in some animals—dogs and horses, for instance—may be easier than in those that mask suffering as a matter of survival, as is the case for such prey species as rabbits and rats.

Dr. Robertson identified three kinds of pain: physiologic, clinical, and neurogenic. Pain can also be talked about in terms of duration, and whether it is acute or chronic. Physiologic pain is necessary for survival, alerting us to potentially harmful stimuli and eliciting a quick response, such as releasing a hot iron before sustaining tissue damage. Clinical, or pathologic pain happens from an injury.

The last of these, neurogenic pain, is the most disturbing and mysterious of pain types. It is pain that defies explanation because it has no known cause. A person complaining of pain in a limb that has been amputated is experiencing neurogenic pain. Dr. Robertson believes that sudden, unexplained aggression in animals might be attributable to neurogenic pain.

Alleviating animal pain is necessary for ethical and clinical reasons, she said. Animals are a valued part of society and are to be protected from needless suffering. From a clinical standpoint, pain is counterproductive to animal well-being. Untreated pain can lead to weight loss, aggression, self-mutilation, and heightened sensitivity to pain.

Dr. Robertson believes that veterinarians must commit themselves to aggressively controlling animal pain. "My philosophy is that, while it may be difficult to recognize pain in animals, we always need to give the animals the benefit of the doubt," she said.

To further animal welfare, Dr. Robertson advocates refinement of current treatment methods, with emphasis on pain recognition and control, along with exploration of new analgesic medications and ways of administering them.

"Conquering pain is something interesting," Dr. Robertson said. "It will benefit us, as well as animals, if we take the time to do so."