Role of Patient History for the Workup of an Itchy Dog


Ashley Bourgeois, DVM, DACVD: We’ve talked a lot about history and past discussions we’ve had about our specialties. We are both involved in specialties for which history is extremely important. In fact, both of us can make a good chunk of diagnosis, or really knowing a big part of the plan, based on the discussion with the owner. How important is the patient history when working up an itchy dog? I’ll start from a dermatologic standpoint, but then I’d love to hear your take from the behavioral standpoint.

For me, it is truly 80% of it. If I hear that a dog is itchy, then I can back up and start to really dive into what that has looked like for that pet. Is that a pet that has been itchy since they were 5 months of age, and they started with otitis, and head shaking. Then I’m going to really dive deep into things like is there a history of gastrointestinal [GI] upset? We know there are food allergy dogs that show us otitis and GI signs very young. I’m really going to home in on the concern for doing a diet trial in that pet.

That’s going to be very different from a dog who presents to me as itchy. They’re 5, and it’s been going on for 2 years, but it happens only in the summer. Or at first it started as happening just in the summer, and now it’s a year-round problem. That’s a much different history. I may not be as inclined to put the time or effort into a diet trial, at least initially, because I already know that pet has environmental allergies. Are there other pets in the house that are itchy? That might indicate something like a flea problem that we need to address. Is it a pet that is 12 years old and never had any skin issues, and all of a sudden became really itchy when they’re very senior? Maybe I look closely at that pet to make sure I’m not more worried about an endocrinopathy or something really off-kilter, like cutaneous lymphoma, which can make dogs be really itchy when they’re older. It’s not that pets can’t be itchy and get those allergies when they’re older, but I’m still going to have on my radar other things that could be more likely based on that history.

Sometimes we have a 12-year-old dog referred to us, and they do have that long history of allergies. We have to dive deep into seeing, do we have resistant pyoderma? There’s a whole list of things that could happen with that. History really allows us to look not only at age but at seasonality and other concurrent signs. I’d say another big thing I like to look for in the history of an itchy dog is response to previous medications. A classic is a pet comes to us and says, “Apoquel worked great for 2 years, and all of a sudden, it’s not working anymore.” Is it truly that it’s not working anymore because the allergies got worse? Or is it because I need to look for that bad infection that could be masking the results of that drug? From a dermatologic standpoint, history is important. I know you’re going to feel the same way about behavior. What behavioral questions might you dive into with the history, to really look at that etiology?

Christopher Pachel, DVM, DACVB, CABC: You’re right. It’s so important in the specialties that we have. As you were listing some of those individual things, I could hear myself rewinding back to my dermatology days. I was like, “For that 1 I’d probably be doing a skin scrape, and for that 1 I’d be doing this.” Even thinking about those different patterns really guides your diagnostic testing. Am I pulling blood for endocrinopathy screening? Am I doing cytology? Am I concerned about the feet, even if they look OK? Am I getting out that little scraper to get into those toe folds, and all the toenail folds, which I know you love to do? It’s the pattern that really determines what we do next and how we proceed.

That’s the same for behavioral cases in that we often think about whatever our behavior of focus happens to be. That could be a broad lens, or it could be pinpoint. We look at that and say, “What are the antecedent conditions under which that behavior does or does not occur? That starts to give us a little more of a correlation. Doesn’t automatically mean causation yet. But we’re looking for those correlations, and the patterns that exist, as you’re saying. If we’re talking seasonality, for example. I hear certain things there too. I say, “Seasonality—does that mean this is a dog who’s been indoors all winter, in the rainy season, and now the doors and the windows are open?” From a behavior perspective, we may have a greater level of exposure to social stressors in the world. If that’s an animal that may experience fear or anxiety or stress, we could see that seasonality start to manifest in different ways as well.

Even though we’re looking for individual details that are different from the dermatitis vs behavioral focus, the process in which we’re looking at that is very much the same. Truthfully, when I’m getting that history—as you said, 80% of what we’re doing is there. That’s very much the case for what we see in behavior. If I’m seeing a patient in the office, for example, or over a telemedicine consult, or even if I’m in the home there to directly observe, each scenario is different from the next. The behavior patterns tend to shift there as well. I can’t always trust only what I’m seeing directly in front of me. I have to say, “Wait a minute, is what I’m seeing consistent with the pattern that’s also being reported, or if there’s a significant discrepancy, I probably need to chance that down a little.” It is that extensive history that’s going to give me that level of understanding that allows me to say, “I’m confident that I’m on the right path,” or, “Pause button. We need to take another look before we go any further.”

Ashley Bourgeois, DVM, DACVD: I never thought of seasonal behavioral issues. That’s really interesting. I suppose, depending on where you are, that could absolutely be true. If it’s frigidly cold, or somewhere where it does rain a lot. That’s really interesting to me.

Christopher Pachel, DVM, DACVB, CABC: I got an update from a client today saying, “We’re done with the worst of the season. This is a dog who’s noise sensitive, and they respond negatively to the HVAC [heating, ventilation, and air-conditioning] system that the neighbor has. Winter is tough for this dog because the neighbor’s heat unit keeps kicking on and off. We’re going to be coasting until probably November for that dog.” This is the third season in a row. We’ve documented it, we know what it is, so we manage.

Ashley Bourgeois, DVM, DACVD: That is very interesting. I never thought about it. I never thought of another specialty appreciating seasonality. That’s pretty cool. We’ve talked before about videos and you’re the 1 that taught me about that methodical licking as being more behavior that could cause things like acral lick dermatitis. Do you find videos clients show you, especially in behavior, where they might change what they do in the hospital vs at home? Do you find videos helpful?

Christopher Pachel, DVM, DACVB, CABC: Absolutely. It gives me that opportunity—even as I’m gathering the history, if they’re able to grab me a 30-second clip, even if it’s a snippet of what that behavior looks like, it gives me the opportunity to ask questions. We’re talking about this dog’s licking, and let’s say we’re talking about going down the stereotypical path, wondering whether it’s a behavioral issue, or trying to differentiate it from dermatitis. We may say, “On a scale of 1 to 10, 10 being the worst episode you’ve ever seen, what am I seeing in this video?” “Oh, that’s a 4.” “Cool. What would make it a 10?” I’m getting into the little nitty-gritty details that allow me to determine not only what might look different with various manifestations of that particular condition, but where am I at in the overall treatment spectrum? What’s the urgency? How does this show up?

It gives me the subtle details that clients don’t know to report. As you and I have chatted about, that specific detail you’re mentioning—a slow, methodical repetitive licking with almost a blissed out or highly stressed, depending on which way you interpret it—is very different from the dog who is loose, soft, and social and then abruptly interrupts what they’re doing to start biting on the bottom of their foot. It’s very acute, very episodic, almost frantic in nature. Then it’s done, and we go back to life as usual. Those are 2 completely different patterns. But to the client, they may think both are itchy or both are licking. Or something along those lines. I wouldn’t necessarily be able to tease out those subtleties because there are so many variations on those themes, unless I have the individual variance that I’m looking at for that particular animal directly in front of me.

Ashley Bourgeois, DVM, DACVD: Yeah, that makes a ton of sense.

Transcript edited for clarity.

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