Boosting the Odds of Recovery
As they work to advance the science of pain management, the Cummings School's anesthesia team and clinicians bring relief to their patients — and better outcomes.
The red-tailed hawk is showing signs of high stress—even bursts of aggression—and isn't eating. The wood thrush is sitting immobile in its cage, its feathers fluffed. The dog is standing calmly in its run, facing away from technicians. The elder cat spends its days sitting in a corner. The horse is standing perfectly still in its stable with lowered head.
What do these animals have in common? All are giving off clear signs of pain that people were largely oblivious to until about ten years ago. "We weren't ‘listening' because we don't speak the same language," states anesthesiologist Dr. Alicia Karas, N85, V89, VR95, assistant professor of Clinical Sciences and a member of the Board of Directors of the International Veterinary Academy of Pain Management. At professional meetings and conferences, Karas overturns old attitudes about animals and pain by showing her videos of animals' behavior before and after administering pain medication. "People are horrified even though I show them what they're used to seeing on a daily basis," she says. "They're just seeing it in a different way." With grant money she developed a video course to help veterinary technicians recognize, assess, and manage pain, which she distributes free to technician schools.
Many animals in pain are programmed to try to act as normally as possible due to an innate fear of predators. It took strategies such as remote video monitoring to begin to understand the often quiet behaviors of animals in pain. Ill dogs that might greet handlers cheerfully, for example, will show their pain in private. This leads to a second insight: dogs that don't put on a happy face at the sight of a caregiver, standing quietly off to the side and facing away, are too painful even to fake it. Veterinary technicians at Cummings are now trained to detect even subtle signs like these and alert clinicians.
Understanding the Impact
Cummings is fortunate to have three anesthesiologists on its faculty as well as its medical and surgical units: Dr. Lois Wetmore, assistant professor of Clinical Sciences and head of the anesthesia team; Dr. Cheryl Blaze, assistant professor of Clinical Sciences; and Karas. All three point to technicians, however, as key members of the anesthesia team. "They are amazing care professionals with such ability and awareness," enthuses Karas. "In fact, all of our awesome hospital staff work towards the goal of reducing the pain and stress that comes from being in the hospital." Their presence allows the anesthesiologists to take time to consult or collaborate with clinicians in all areas of the Cummings hospitals on follow-up or questions for every imaginable patient species.
A ferret receives anesthesia.
Cummings anesthesiologists and wildlife clinicians are continually expanding their knowledge of how pain and pain relief vary from species to species—even from one animal to another within a species. Most animals brought into the Wildlife Clinic are obviously injured, so clinicians automatically medicate for pain, as in a recent case involving a red-tailed hawk. When no injury is evident they look for species-specific signs of pain before medicating it. For example, a Cooper's or sharp-shinned hawk, which grabs its prey on the fly, normally responds to the tricks technicians use to induce it to eat. If it doesn't respond, then they know it's in pain.
Attitudes about pain management at veterinary schools and throughout the profession have greatly progressed in the past ten years. When Wetmore was in veterinary school, "we were taught that an animal needs to feel pain because it doesn't know enough not to bother the site and harm itself," she recalls. "If you keep believing that year after year, you learn to ignore pain—particularly when an animal is suffering silently," she adds. Today veterinary medicine recognizes that pain reduction actually speeds healing. And Cummings clinicians take the perspective that complete recovery lies in preventing changes that can occur with repeated painful stimuli. These changes, known as "windup," result when pain messages sent to the spinal cord over time cause new nerve endings to sprout, amplifying the pain. Ultimately an animal will have a painful response to any stimuli in that area. This condition, stresses Wetmore, is both preventable and treatable: "We know the specific receptors that cause windup, and have drugs that can reduce it and return the animal to a non-painful state."
An important goal is to provide maximum benefit with the least amount of drugs. During surgery, anesthesiologists combine locally infused analgesics with gas anesthesia. "By using several different drugs at once, you can get by with much less," explains Blaze. "It's more than just an additive effect; they work synergistically." Epidurals and other local blocks, such as those used in dentistry, are also encouraged. "These aren't particularly new strategies, but they tend to have been ignored in the past," says Blaze. "We're using them much more often than we did ten years ago." The same is true of non-drug therapies such as heat or ice.
The anesthesiologists take in constant feedback on what treatment is or isn't working and use it to advance their knowledge, says Karas. "A lot of ‘new' remedies we're exploiting have been in our cabinet all along." For some drugs, old misconceptions no longer apply, such as the myth that opioids (morphine-like drugs) cause mania in cats. This conclusion was reached decades ago from a study that used dosages well beyond those considered effective. Also, cats don't get sleepy from opioids, as dogs do. They get, well, lusty—and some cats might find that altered state distressing. "But if a cat is very painful in the first place," says Karas, "it reacts to opioids remarkably well. Veterinarians now use them quite successfully in cats."
Wildlife clinicians often need to use their knowledge of domestic or exotic species to determine what might work best on their patients. "We can extrapolate from studies done on the use of pain medicines in members of the parrot family to work with wild birds that have similarities, and remedies for ferrets and rabbits can apply to members of the weasel family," explains Dr. Flo Tseng, assistant professor of Environmental and Population Health and assistant director of the Wildlife Clinic. But it's a challenge to gauge whether a remedy is providing relief.
"Standard tests to assess analgesic effects are rarely available for non-mammalian species," notes Tseng. "Plus wild animals are usually stressed by being captive, and we need to differentiate that from the pain." Patient stress can both delay healing and affect clinicians' ability to administer drugs. The goal is to be as hands-off as possible, but the most effective medications often require hands-on administration every two to four hours. The stress this induces in the animal diminishes or even cancels out the efficacy of the drug. The solution is to use a remedy that works perhaps a little less well, but can be given just twice a day with good effect. Once the animal is eating, clinicians can switch to a non-steroidal anti-inflammatory (NSAID) or other drug that can be put in its food.
A New Strategy
The key to effective pain treatment for any animal, wild or otherwise, is close observation and monitoring. This is necessary not just because every animal responds to medication differently, but because each one reacts differently to painful stimuli. Veterinary students are trained to examine each patient's history and blood work thoroughly and choose the best protocols to use; a particular animal might need something a little extra or different from what was expected. Findings like this can lead to new protocols for a better outcome, and sometimes a whole new way of doing things. A good example is a handy device called a "wound soaker catheter," one of several improvements in peri-operative pain management in the last several years. Like many other veterinary inventions, it was adapted from human medicine.
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Profile written by Leslie Limon
Photos by Melody Ko, University Photographer
This story ran online on October 15, 2007. It originally appeared in the Winter 2006/2007 edition of Tufts Veterinary Medicine.