August 01, 2001

 

 The problem with pain

Veterinarians are making a thorny issue a priority  


Posted July 15, 2001
 

When Dr. William J. Tranquilli first started teaching veterinary anesthesiology at the University of Illinois College of Veterinary Medicine in 1979, his primary focus was showing students how to safely anesthetize animals so they were not in danger of suffering heart or lung failure. Even after becoming board certified, Dr. Tranquilli—like others in his specialty—did little to help patients cope with pain after surgery.

But by 1995 Dr. Tranquilli had made pain management an integral part of his course. He encouraged students to use preemptive and postoperative analgesic drugs, as well as regimens once unheard of, such as multimodal analgesia. Today, Dr. Tranquilli, a professor of clinical medicine in anesthesiology, advocates aggressive treatment for acute and chronic pain. He has also co-authored a book for practitioners on managing pain in small animals.

"When we say 'pain management,' it's not about giving a drug at one point and then saying 'OK, I gave the drug, I did my job,'" he said. "It's management. In other words, you don't really know [how much the patient is suffering], so you start to treat it, see how it responds, ask 'Do I need to give him more, or can I just leave him alone?' It's an art, it becomes interactive."

Veterinarians dedicate themselves to alleviating animal suffering, and yet they may frequently prescribe too little medication to do any good to effectively treat pain. This discrepancy can partly be attributed to the scientific community's debate over whether animals perceive pain the way humans do. The argument laid the groundwork for the profession's approach to treating animal pain. At the veterinary schools, students often learned that pain could be useful for keeping convalescing animals immobile.

The prevailing opinion today is that human and nonhuman mammals process painful stimuli much the same way. Most of the pain management strategies in human medicine are derived from physiologic models of dogs, cats, and rats, according to Dr. Tranquilli.

His philosophic transformation can be traced to the early '90s as part of a grassroots movement in companion animal medicine of anesthesiologists, surgeons, oncologists, and critical-care specialists—people familiar with the pain caused by injury and disease. Armed with an improved understanding of pain, along with a battery of safer, more effective opioids and nonsteroidal anti-inflammatory drugs (NSAIDS), they started trying to more effectively manage their patients' pain.

Pain is problematic from a clinical perspective because it is personal. Despite veterinarians' years of training, determining whether an animal is suffering is a guessing game for them because they are dealing with nonverbal patients. What's more, species exhibit pain differently, and pain thresholds vary with the individual animal.

"Depending upon their experiences and the kind of species they are, you're going to get this huge spectrum of responses to injury and pain," Dr. Tranquilli said.

The human health care profession also finds itself wrestling with the complexities of pain management. Physicians are increasingly being criticized for not providing relief for suffering patients. One example of how big an issue this has become is the finding of a California jury that in June found a doctor liable for failing to prescribe pain medication for a terminally ill patient who later died of cancer.

The Joint Commission for Accreditation on Healthcare Organizations, an accrediting body for nearly 19,000 U.S. health care organizations and programs, declared in 1999 that patients have a right to effective pain management.

The catalyst cited frequently for the evolution of pain management in companion animal medicine was a study published in 1993 by researchers at North Carolina State University College of Veterinary Medicine. It revealed that cats and dogs at the school's teaching hospital were receiving little treatment for acute postoperative pain (see JAVMA, May 1, 1993, page 1485).

"That was kind of a wake-up call to a lot of people that we're not doing a very good job," explained Dr. Peter Hellyer, chair of the committee that wrote the animal pain treatment guidelines adopted by the American College of Veterinary Anesthesiologists in 1998 (see JAVMA, Sept. 1, 1998, page 628).

Dr. Hellyer is an associate professor of anesthesiology at Colorado State University College of Veterinary Medicine and Biomedical Sciences. He explained that during the '70s and '80s, the field of veterinary anesthesiology focused primarily on the cardiopulmonary effects of the anesthetics. By the '90s, anesthesiologists were more confident in the drugs' safety, allowing them to focus on pain control. Dr. Hellyer attributes the tendency to undertreat pain to what he sees as a "knowledge deficit" among companion animal practitioners.

"Every analgesic out there has potential adverse side effects to it, and if you never really got a comfort level with using morphine or an NSAID or local anesthetic, you might really be reluctant to start integrating those into your practice," he said.

Society is increasingly expecting science to provide the means for living a long, relatively pain-free existence. People are starting to expect the same for their pets, and the pharmaceutical industry and veterinary profession have taken note. This year, Pfizer Animal Health partnered with three universities to form the Companion Animal Pain Management Consortium. Its goal is to develop and promote improved pain management techniques. (Dr. Tranquilli is part of the consortium.)

Several scientific articles and books proposing pain scales and management strategies have been published. Many veterinary colleges now offer courses on methods for alleviating pain, and pain management is frequently offered as part of continuing education. In the realm of organized veterinary medicine, the AVMA this April adopted a policy encouraging practitioners to treat animal pain; the AAHA is considering developing pain management standards for hospital members.

"There have been tremendous advances that have been made in understanding the complexity of pain and understanding some of the treatment options," Dr. Hellyer said.

Regarding laboratory animal research and food animal production, the issue of pain management gets complicated. Unlike the emotional utility derived from the dog or cat thought of as a family member, food-producing animals are valued as economic resources; laboratory animals are valued for the medical breakthroughs that might result from their use.

Congress passed the Animal Welfare Act in 1966 and has amended it several times since, to protect some warm-blooded animals from inhumane treatment. States and municipalities have passed their own ordinances to this end. Laboratory animals are by far the most regulated animals in this country. Research facilities are licensed and inspected. Each facility is required to have a committee that reviews all experiments to determine whether the pain to the animal is warranted, and whether less painful alternatives were considered.

When it comes to pain management for food animals, Congress and the states have less to say. The Animal Welfare Act does not apply to farm animals, although there are laws requiring the humane slaughter and transportation of livestock. A number of standard production practices are done without the benefit of anesthetics or analgesics—dehorning, ear notching, and beak trimming, for example.

"We do an awful lot of things to food animals with no pain management at all," said Temple Grandin, PhD, an animal scientist recognized for her innovations in food animal welfare. Animals and poultry undoubtedly feel pain and will avoid it, Dr. Grandin said, yet they sometimes instinctively mask their suffering.

Most good ranchers do the painful procedures on the animals while they are young, but many don't, according to Dr. Grandin. The producer groups and professional organizations have worked with veterinarians to draft welfare guidelines to ease suffering associated with farm production practices, but these are recommendations, she said.

Economics and drug availability drive pain management in food animals. In some cases, it is more cost-effective to euthanatize a sick or injured animal rather than treat it. For food safety reasons, there are but a handful of approved anesthetics and analgesics for livestock.

"We are constrained by AMDUCA and economics," said Dr. Jim Reynolds, chairman of the AABP Welfare Committee.

Dr. Reynolds does not see a need for more government oversight in food animal production; he believes in the sufficiency of the welfare guidelines, which he characterized as an effort by the industries to preclude regulation. And while food animals in Europe are more regulated than in the United States, Dr. Reynolds, who has worked extensively in Europe, most recently in England during the foot-and-mouth disease outbreak, said food animals are not treated any better there than here.

Any substantive changes in pain management practices for food animals will be because of government intervention or for economic reasons, or a combination of both. Dr. Wendy J. Underwood, DACVIM, a food animal practitioner working for Eli Lilly and Company, anticipates that the global economy will compel U.S. food animal producers to deal more directly with this issue. "In order to sell our products overseas, I think in the future we'll have to do a number of things, one of which will be to certify we're treating our animals properly. Part of that will be providing pain relief."