JOURNAL SCAN
Opinion No. 2: ‘My patients benefit’ - Dr. Dani McVety
Like Dr. Petty, Dani McVety, DVM, founder and CEO of the Lap of Love Veterinary Hospice network, says the
study results are not unexpected. “I looked at the study, but I didn’t really have to,” she says. “It’s truly no surprise
to me or anyone else who’s been using tramadol for years that it’s not the perfect pain medicine.”
But she says hospice practitioners occasionally need to push the boundaries on medical comfort measures,
and for her, tramadol will continue to have a role in managing veterinary pain.
“When I prescribe tramadol, I tell my clients that it’s not used directly for pain reduction, but more like a glass
of wine,” she says. “Sometimes you need one; sometimes you need two or three to get calmed down a bit.
But if we’re leaning on a very high dose for more than one to two nights, we have a quality of life issue and
need to have a separate conversation.” In other words, Dr. McVety uses tramadol in a limited capacity to get
a very specific reaction from the pet: calmness. “Sometimes just reducing the emotional wind-up that occurs
with pain is helpful to our clients and their pets,” she says. “This is why we will not stop using this medication,
combined with adequate pain relief.”
Opinion No. 3: ‘The jury is still out' - Dr. Ralph Harvey
Ralph Harvey, DVM, MS, DACVAA, is associate professor of anaesthesiology at the University of Tennessee
College of Veterinary Medicine. He says trying to understand all the nuances of how living things experience
pain—and how various drugs affect that experience—is like trying to answer the question “What is truth?”
“I have a great deal of faith in Budsberg and the validated models he uses,” Dr. Harvey says. “The work he has
done is meaningful and useful, while not surprising. But many veterinarians far more well-known and expert
than I am continue to advocate for the use of tramadol. And veterinarians continue to have the impression that
it’s beneficial.”
When Dr. Harvey gives talks on pain management, he asks participants to raise a hand if they’ve heard experts
say there’s little to no evidence supporting the use of tramadol in veterinary patients. Many hands go up. “Then
I ask how many of them are using tramadol anyway,” Dr. Harvey says. “And many hands go up or stay up.” In
the pyramid model of evidence-based medicine, Dr. Harvey continues, double-blind placebo-controlled studies
such as Dr. Budsberg’s rank higher than the bottom level of expert opinion and clinical impression, which can
be clouded by bias and wishful thinking. But still, he believes the jury is out on whether tramadol has value in
mitigating the experience of pain in veterinary patients.
The problem, he proposes, lies in thinking of tramadol as an analgesic. “We do better to think of it as an
emotion-modifying drug—at least in those animals that produce the right metabolite,” he says. “Dogs are
extremely variable in their ability to produce that mu-receptor-binding metabolite. Some dogs do; others don’t.”
Dr. Harvey refers to the work of psychologist Ronald Melzack, who several decades ago presented a theory
differentiating between two aspects of pain. The discriminative aspect of pain, Melzack says, is highly localized,
specific and sharp—it’s what you would experience if you touched a hot stove. The affective aspect of pain is
not how it feels but how it makes us feel—it’s the suffering or emotional component of pain.
“The affect of pain is less distinct and slower to come across, and it degrades engagement with life,” Dr. Harvey
says. “It’s what Freud was talking about when he said a man with a toothache cannot be in love.” Of course, no
validated assay exists for the emotional experience of animal pain, so it’s extremely difficult to provide evidence
that a drug like tramadol is efficacious in relieving it. Another confounding factor is that tramadol is best used
as a complementary therapy, Dr. Harvey says, which muddies the waters in terms of knowing which drug is
causing which effect.
“But absence of evidence is not evidence of absence,” Dr. Harvey says. “Our greatest limitation in evaluating
pain is our ability to recognize and quantify it, especially when it comes to validated models for the suffering
aspect of pain. This is a new frontier we are only just beginning to explore.” Issues surrounding tramadol use—its
status as a controlled substance, the potential for human abuse and diversion, the risk of adverse effects such
as serotonin syndrome, and patients’ varied ability to metabolize the drug—must all play a role in an individual
veterinarian’s decision to use it or not. But is this study the last word on the subject? No, Dr. Harvey says. “My
impression is that, while I have great respect for this study, the metric is limited to the sensory rather than the
emotional component of pain,” he says. “But Dr. Budsberg has elevated the conversation, and this is a rich area
for continued discussion.”
vet360
Issue 05 | NOVEMBER 2018 | 34