Assessing Pain in Companion Animals

B. Duncan X. Lascelles, BVSc, PhD, DACVS: Hello, and thank you for joining this American Veterinarian^® Peer Exchange^® on advances in small animal pain management. Osteoarthritis (OA) and other chronically painful conditions are alarmingly common in our veterinary patients. But, in too many cases, these conditions go undiagnosed and untreated for far too long. Even acutely painful conditions don’t always receive the attention they should in daily practice. We’re fortunate to have safe and effective treatment modalities at our fingertips, and exciting new developments are on the horizon that might help us recognize and manage pain more effectively in our patients. In this Peer Exchange^®, we’ll discuss some of these advances and how they might impact our approach to pain in veterinary practice.

I’m Dr. Duncan Lascelles, and I’m a professor of surgery and pain management, and director of the Comparative Pain Research and Education Center at North Carolina State University in Raleigh, North Carolina. I’ll be moderating today’s session. Participating today, we have several distinguished members of our panel: Dr. Mark Epstein, senior partner and medical director of TotalBond Veterinary Hospitals and Carolinas Animal Pain Management in Gastonia, North Carolina; Dr. Margaret Gruen, researcher at Duke University’s Canine Cognition Center, Durham, North Carolina, and adjunct professor at North Carolina State University; Dr. Sheilah Robertson, the senior medical director of Lap of Love in-home, end-of-life-care for small animals, based in Gainesville, Florida; and Dr. Bryan Torres, assistant professor of small animal orthopedic surgery, and director of the Motion Analysis Laboratory at the University of Missouri, in Columbia, Missouri. Thank you so much for joining us. Let’s get started.

Margaret, we’ll start with maybe a question for you. We’d all like new therapies, but what are the most significant challenges to developing these new therapies?

Margaret Gruen, DVM, MVPH, PhD, DACVB: Thank you, Duncan. I think that’s a great question. Some of the really significant challenges that we have are in recognizing pain in our patients, educating owners about the presence of pain and the contributing factors and then really having efficacious and validated tools to understand when they’re in pain and when they’re feeling better, so that we can really critically assess these new therapies.

B. Duncan X. Lascelles, BVSc, PhD, DACVS: Are there particular problems in the assessment when we’re involving owners? People talk about the placebo effect. Is that an issue? Is that a problem in developing new therapies?

Margaret Gruen, DVM, MVPH, PhD, DACVB: It’s a big problem. It’s a problem in human health and it’s a problem in veterinary medicine. And, in veterinary medicine, we even have a further issue—we’re 1-step removed. So, we have some objective tools, but when we’re asking owners about their pet’s behavior and their pet’s pain, we’re asking them for their assessment of it. And these are people who may or may not have ever thought about what their pet looks like in pain before. And so, we have layered in their expectations—their hope for it to work. All of that complicates our picture when we’re asking owners about how their pets are doing. We have what we call the “caregiver placebo effect,” where they believe that it’s really effective when some of our objective tools suggest that it’s not. And then, maybe we actually even have an interplay, where if they believe that it’s effective and they interact with their pet differently, it is effective. So, we have what we’re starting to call the “placebo by proxy effect,” as well.

B. Duncan X. Lascelles, BVSc, PhD, DACVS: And Bryan, you’re involved in clinical research looking at new, novel analgesics. What tools do you find are most effective in your hands?

Bryan T. Torres, DVM, PhD, DACVS-SA, DACVSMR: For me, I think about how I am going to assess pain in these patients. I break it into what can I use to give me an objective measure and what can I use to give me more of a subjective measure. And I think they work really well together. So, objectively for dogs, I really like data analysis. I like looking at how they move and how much weight they bear on the leg that may hurt. In a dog with one-sided issue—maybe a cruciate tear or hip dysplasia in that left rear limb—how does that change pre- and post-treatment? Are they putting more weight on that limb? Is the range of motion changing in those joints? I think you have to combine that with subjective evaluations. We need to look at how these owners are assessing their patients at home, and I think that’s important to make sure that we’re using both of those methods.

Now, that’s for dogs. Cats are a little different. They’re a different creature; they are not dogs. I know that Dr. Gruen here has done some excellent work with cats, in considering how we might be able to assess their pain in a different way than getting them into the lab and trotting them over to some force plates, pressure walkways, and everything else.

B. Duncan X. Lascelles, BVSc, PhD, DACVS: You use some activity monitoring, is that right?

Margaret Gruen, DVM, MVPH, PhD, DACVB: Yes, activity monitors are the mainstay of what we’ve used for looking at efficacy. So, we look for changes in a cat’s activity over time. Cats have a wide variation in their overall activity levels, so we really have to look at an individual cat and their change over time. They don’t participate really well in our walkway studies. They don’t enjoy coming to the veterinarian as much as we wish that they did. Activity monitoring, at home, has been really useful for us. But, you’re right, it really has to combine with what matters to the owner. What improvement do we see in the activity monitor, and how does that actually translate to what owners’ think are better? Maybe what they’re really concerned about is whether he or she can jump up on the bed to watch television with them. So, we need to balance what’s important to the owner, and what they notice as a clinical improvement with what we feel is improved on in any of our objective measures.

Bryan T. Torres, DVM, PhD, DACVS-SA, DACVSMR: One of the things to consider is for many, many years, a lot of the tools that we used to evaluate them, as far as their gait goes, were really limited to universities and large institutions. And that is somewhat changing now. We have more instruments and more technology that’s available to private practitioners. And so, that hopefully will change in the coming years. The subjective and the owner assessments are available to everybody.

B. Duncan X. Lascelles, BVSc, PhD, DACVS: Sheilah, I just want to bring you in here to discuss the owner assessments. I think there are a couple of areas we haven’t explored in owner assessments, particularly with respect to quality of life. Would you like to comment on that?

Sheilah Robertson, BVMS, PhD, DACVAA, DACAW: Yes, a lot of what we’re talking about, today, is focused on osteoarthritis and the pain associated with that disease—and it is across a wide range of ages. But what we really are looking at, I think, is the quality of life for that animal, and the impact that pain from the OA has on their life. I don’t know that all the tools should be disease-specific, because if we think about some of the data that you and Margaret have published, if we actually look at the data, well-over 70% of cats with osteoarthritis are likely to have chronic kidney disease as well. And so, there could be days where their chronic kidney disease is actually what’s impacting on their quality of life more than the pain from their joints.

I think having health-related quality of life assessments, and with the new generation and technology that we have now, a lot of these new tools are going to have to be computer-based—iCloud-based—the owner is sitting in their own home looking at what their dog or their cat is actually doing, and is answering the questions. I think when you get an insight into what’s happening in the home, that is very different from what you see, especially with cats. When a cat comes to a clinic, they’re not going to behave normally. They’re inhibited; they’re scared. I think in-home assessments, whether they’re done via the owner with a Smartphone videoing and showing you footage or whether they’re sitting in their home assessing their animal, I think that is going to engage a lot more people in better assessments.

B. Duncan X. Lascelles, BVSc, PhD, DACVS: It sounds like we have a number of assessment tools—objective, subjective—maybe measuring different dimensions impacted by pain.