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The practical canine allergic dermatitis workup
Natalie Marks, DVM, CVJ on why it's so important to diagnose and treat allergic itch effectively
This content is sponsored by Zoetis.
Adam Christman, DVM, MBA: Hello, everyone and welcome to a great discussion where we're going to be talking about the practical canine allergic dermatitis workup. Who has time for anything else? And we want to thank our friends from Zoetis for supporting this great discussion. Joining me today is Dr. Natalie marks. How are you Dr. Marks?
Natalie Marks, DVM, CVJ: I'm great. Dr. Christman. How are you?
Adam Christman, DVM, MBA: Good. I'm so glad that you're here. We're gonna have a great conversation about this. My name is Adam Christman Chief Veterinary Officer here at dvm360®. I’ll facilitate this great discussion, and little bit about our friend Dr. Natalie Marks. So, Dr. Natalie Marks is an internationally renowned veterinarian, and after running the largest small animal practice in Chicago for over 10 years, Dr. Marks is dedicated to helping pet owners and veterinarians work as a team to ensure the health and happiness of our beloved furry family members. Dr. Natalie Marks obtained her bachelor's degree with high honors in Animal Science from the University of Illinois in 1998, and then proceeded to obtain a Master of Veterinary Medicine and Doctor of Veterinary Medicine degree with high honors from the University of Illinois College of Veterinary Medicine. Dr. Marks received the prestigious Dr. Irwin Small First Decade Award, presented to a veterinarian that has contributed most to organize veterinary medicine in his or her first decade of practice. In 2012, Dr. Marks was awarded Petplan’s nationally recognized veterinarian of the year Additionally, she was awarded America's Favorite Veterinarian by the American Veterinary Medical Foundation in 2015. When Dr. Marks is not working, she treasures her time with her family and her 3 wonderful children, Sophia, Evan, and Madeline Dr. Marks loves traveling scuba diving, cooking, and spending time outdoors, especially anywhere there is a beach. I love that. All right. So, let's get into this great discussion. So why is it so important that we diagnose and treat allergic itch effectively?
Natalie Marks, DVM, CVJ: Well, skin allergies are the number 1 canine case presentation that we see in general practice. And we know that chronic allergic pruritis can not only make a patient uncomfortable, but it really can erode the human animal bond with today's longer wait times for scheduling appointments due to increased client demands and staffing challenges. It's important to get the treatment right from the beginning, vs having to tell owners to come back again and again when they're disappointed that their dog is still itching.
Adam Christman, DVM, MBA: So true. So, Dr. Marks, you have a new itchy dog in the exam room. Let's picture this: You've taken a good history, and now you are starting your physical exam. You make a strong point that pattern recognition can be very helpful in dermatology. Why is that?
Natalie Marks, DVM, CVJ: I love pattern recognition because it really can help in dermatology cases to lead us towards that important differential diagnoses list and effective treatments. So, here are some common patterns that I want people to remember. Flea allergic dermatitis, we see changes at the tail base, the lumbosacral area, the inner thighs, and also the caudal medial thighs. For a potential scabies patient, we're looking at the ear pinna margins, the elbows, the hocks, the ventral abdomen, sort of that diagonal down the body. And then for food allergic or atopic dermatitis patients, some of the patterns we look for are involved in the face, the ears, the paws, the palmar metacarpals, the flexural areas of the 4 limbs, the axial, and the ventral.
Adam Christman, DVM, MBA: So, that makes sense. So, once we've done our history, physical exam…What is an easy diagnostic approach for first time acute pruritic dog with allergic dermatitis?
Natalie Marks, DVM, CVJ: Well, we know there can be many causes of pruritis right, including parasites, bacterial and yeast infections, flea allergic dermatitis, food allergies, and of course, atopic dermatitis. But for a first time acutely pruritic case or a dog with a flare of allergic pruritis once or twice a year, we likely don't need to address all of these possibilities. Instead, what we can do is follow a simplified and streamlined approach. So, I want to focus I want everyone to think about 3 key steps. The first is we need to stop the allergic pruritis. This will provide comfort to our patient and peace of mind to the owner, which then strengthens the trust and the confidence of our pet parent with that veterinary health care team. The second thing we want to do is rule out parasites with a nice access lane. I think everyone's pretty comfortable with that. And then the third thing is we need to identify and treat any of our bacterial or yeast skin infections. And that's where cytology is so important here to help you diagnose the type of skin infection that's present. These first 3 steps are foundational to the diagnostic approach and for a dog that flares with pruritis only 1 or 2 times a year. These are the only steps that we really need to do. We don't need to get caught up in discussions about food allergy or the long-term management of atopic dermatitis.
Adam Christman, DVM, MBA: So, what about antihistamines, like we use in people with allergies? Are they a good choice to stop allergic pruritis in dogs?
Natalie Marks, DVM, CVJ: I'm so glad you asked, because if you think that antihistamines may be an option for pruritis, relief and any dog with allergic dermatitis, I want everyone to please stop and consider what members of ICADA, the International Committee on Allergic Disease in Animals concluded after an evidence-based review of all of the relevant literature. They stated that antihistamines are likely of little to no benefit for the treatment of acute atopic dermatitis in the majority of dogs. As in human atopic dermatitis, cytokines, not histamine, are the major itch mediators in dogs with allergic dermatitis. And multiple published studies have shown that antihistamines are not effictive. For example, a randomized placebo-controlled study of cetirizine or Zyrtec vs a placebo showed that there was no significant difference in itch levels from baseline. And no significant difference between the placebo-treated and Zyrtec-treated dogs’ improvements in pruritis levels, with 85% of dogs receiving the antihistamine either stayed the same or got worse over a 2-week time period. There are much better options for our patients.
Adam Christman, DVM, MBA: I mean, that is really great data. But what I hear from practitioners are that antihistamines are cost effective and do no harm. So why don't I try them first?
Natalie Marks, DVM, CVJ: Well, I'm glad you brought that up, too, because this is a really important point. I hear that all the time. But in terms of cost effectiveness, if they don't work, it doesn't matter how cheap they are, it's still a waste of money, especially when they now must come back for a recheck exam and more diagnostics, because the treatment isn't working. And then, you know, well, let's address what about the “Well at least they do no harm” statement. This is really also false, because if they don't work, then they do harm that dog whose pruritis continues and gets worse. This can lead to secondary skin infections, which if repeated, can become resistant and difficult and expensive to treat. They also can harm the owner who's still stuck on that allergy emotional rollercoaster, as well as harming the veterinary practice because they're no longer that trusted partner of the pet parent. So really, if you think about it, the true cost of antihistamines is really quite high.
Adam Christman, DVM, MBA: When you think about it, that way, the cost of using antihistamines for allergic dermatitis really is very high. So, any final thoughts for our veterinary health care teams?
Natalie Marks, DVM, CVJ: Well, in the spirit of getting it right the first time, providing the relief that our pet owners are looking for, and getting them off that allergy emotional roller coaster, I challenge you and everybody in your practice to stop routinely dispensing or recommending those over the counter antihistamines for dogs with allergic dermatitis, because we can and we should do better for our clients and our patients.
Adam Christman, DVM, MBA: You mentioned the first step of stopping the allergic pruritis. This is so important. So, let's shift from ineffective therapies like like antihistamines to a highly effective medication. Can you share how Apoquel can be used here?
Natalie Marks, DVM, CVJ: Absolutely. When considering which therapy to use to stop the allergic pruritis, Apoquel is great for the treatment of allergic pruritis because of its rapid onset of action, as it starts to relieve allergic pruritis within 4 hours, and we have flexibility and how long you can give it. Apoquel is a targeted therapy. It's a selective JAK inhibitor that inhibits the activity of multiple pro-allergic and pro-inflammatory cytokines. Published studies show that Apoquel was very effective and well-tolerated in dogs with allergic and atopic dermatitis. And besides controlling allergic pruritis, Apoquel is also highly effective at controlling skin inflammation due to allergic dermatitis and dogs. In a published study, Apoquel administered orally at the recommended dosing regimen, reduced pruritis and inflammation due to allergic dermatitis to a level comparable to the efficacy of prednisone given at 0.5 to 1 mg per kg daily for 6 days, then every other day, even in dogs with moderately or extremely severe dermatitis.
Adam Christman, DVM, MBA: That's great data to know. So, when you start Apoquel in a dog, how do you do that? How long do you dispense it for? Is there any dose and flexibility?
Natalie Marks, DVM, CVJ: Well, you know, that really depends on the patient and the severity and the type of allergic dermatitis. One of the great advantages of Apoquel is that it has a variable dosing duration on the label up to 14 days, twice a day, and then 1 a day for maintenance. Not every dog needs 14 to 28 days of medication which is great, right? For example, if I had a dog with allergic skin disease with mild moderate hotspot that I'm treating with topicals and antibiotics for the bacterial skin infection, I might only dispense 5 to 7 days of Apoquel for the allergic dermatitis before I recheck that patient. But if a dog is having just a little flare up of allergic dermatitis because that pollen count is high, maybe they only need Apoquel for 3 to 5 days until things get settled down a little bit more. The beauty of Apoquel is that you have that dosing flexibility. And this helps the cost for the owner. Remember, Apoquel is a part of the Zoetis Pet Care Rewards as well, where owners can receive points that can be redeemed for dollars to spend at their clinic. If you want to learn more about that you can go to zoetispetcare.com/rewards.
Adam Christman, DVM, MBA: Okay, so we've covered the acutely pruritic first time or seasonal case. But what if this pruritic dog becomes a more chronic patient who's coming back 3 or more times a year? Would our workup have been more extensive at that point?
Natalie Marks, DVM, CVJ: Yeah, it absolutely would be. In that case, we need to strongly advocate for that full diagnostic workup. The first 3 steps we talked about are to say, stop the allergic pruritis, rule out parasites, and treat that infection. But now we need to add a food trial for those non-seasonal predict dogs. And here we can take advantage of Apoquel’s stop and start feature. For allergic pruritis relief, dogs can get started on Apoquel. And once that diet trial is complete, we can discontinue it and see if the diet alone is helping. After ruling out all the other causes of allergic pruritic, we're left with a diagnosis of atopic dermatitis. And then we can design a long-term maintenance program with Apoquel or Cytopoint as the anchor therapy so we can provide a customized treatment depending on the owner and the pet preference of lifestyle.
Adam Christman, DVM, MBA: Excellent. So, can you describe what you mean by anchor therapy and how this is different from say the multimodal therapy for these chronic cases of allergic or atopic dermatitis?
Natalie Marks, DVM, CVJ: Yeah, absolutely, anchor therapy. This is a term used to describe a single treatment that is sustainable and provides satisfactory control of allergic pruritis for a dog with atopic dermatitis. So, this could be one of the following Apoquel, Cytopoint, cyclosporine, or allergen-specific immunotherapy. And it really depends on what's accepted by the patient, manageable long term by that client, and what achieved satisfactory control for all the parties involved. We can find anchor therapy for most of our patients. Studies show that Apoquel or Cytopoint monotherapy was effective in the majority of dogs. However, some cases need multimodal therapy, and for those, collaborative referral with a dermatologist is most effective. Don't forget, these families are signing on for a lifetime of chronic care that can give and create caregiver burden to that pet parent. This can transfer over to us as veterinary teams and create compassion fatigue and lead to burnout. So, we're really most successful when we ask questions ahead of time and find a strategy that's going to work for the patient and the client at the same time.
Adam Christman, DVM, MBA: Really, really insightful on that. I love that. So, what do we do when the patient on an anchor therapy that has a flare up?
Natalie Marks, DVM, CVJ: That's right. So first, we need to examine that patient and make sure that we've ruled out all of the common flare factors that tend to worsen pruritis things like parasites, fleas and scabies, most commonly, bacterial and yeast infections, and food allergies. Often once these are diagnosed and treated with a veterinary exam versus that phone fix, that previous anchor therapy often goes back to working well and the allergic arthritis is back under control. Again, if it's skin, it needs to come in.
Adam Christman, DVM, MBA: Okay, love that. So, let's switch gears and talk about side of brain. So, what are the benefits of Cytopoint? How do you approach treating a dog with seasonal or chronic allergic or atopic dermatitis when you've decided that Cytopoint is the best option?
Natalie Marks, DVM, CVJ: Of course, so Cytopoint is a targeted anti il 31 monoclonal antibody that provides relief for allergic let me say that again. Cytopoint is a targeted anti il 31 monoclonal antibody that provides relief of allergic rhinitis within 24 hours and lasts for eight sorry. Cytopoint is a targeted anti IL-31 monoclonal antibody that provides relief of allergic pruritis within 24 hours and lasts for 4 to 8 weeks. It's a great choice for dogs under 12 months of age, those that are difficult to pill, have seasonal allergic pruritis, or when owner compliance is really a challenge. Some other really great news about Cytopoint…Because it's an injectable, it's a professional service that stays in your practice. Dermatology can really be a huge profit center to help your practice stay financially healthy as well.
Adam Christman, DVM, MBA: Yes, absolutely. So how do you approach a dog with seasonal or chronic with atopic dermatitis when you decided Cytopoint is the best option?
Natalie Marks, DVM, CVJ: Well, the majority of dogs respond well to the first Cytopoint injection. In a published study of dogs with allergic dermatitis 77% had at least a 50% decrease in pruritis scores. In the pivotal efficacy study, greater than 80% of atopic dogs achieves treatment success by day 3, and 69% maintain their success at day 28 just after the first injection. In dogs with a partial response to the first injection, additional injections may help. In fact, a 2019 study and dogs with atopic dermatitis showed that after the third monthly injection of this product, cumulatively 93% of dogs were considered treatment successes.
Adam Christman, DVM, MBA: Oh, that's a great study. So how would this work in practice?
Natalie Marks, DVM, CVJ: Well, I would recommend an appointment with the owner 4 weeks after that initial treatment to recheck if that dog's a full treatment success. It's important to explain to those owners that most dogs typically get 4 to 8 weeks of relief from one treatment of Cytopoint. And we need to determine the frequency for future treatments as needed. Most dogs will be a treatment success within that first dose. But if that patient had a partial response, I would give a second or third treatment of Cytopoint if needed. In this way, we can give the dog every chance to respond. And don't give up on Cytopoint too soon. Continued communication with the pet parent and the veterinary team is key.
Adam Christman, DVM, MBA: It really is key. Well, this has been so insightful and so wonderful. Want to thank you so much Dr. Marks for joining us as well. And also thank you to our friends at Zoetis. This is great.
Natalie Marks, DVM, CVJ: Thanks for having me. You're welcome.
Adam Christman, DVM, MBA: This video was sponsored by the Zoetis, the makers of treatments including Apoquel and Cytopoint. Zoetis is dedicated to changing the way we approach canine pruriti. to protect the bonds between the vet, the owner, and the veterinary team. Visit apoquel.com/resources for more information. Do not use Apoquel and dogs less than 12 months of age or for those with serious infections. Apoquel may increase the chances of developing serious infections and may cause existing parasitic skin infestations or preexisting cancers to get worse. Consider the risks and benefits of treatment in dogs with a history of recurrence of these conditions. New neoplastic conditions, benign and malignant, were observed in clinical studies and post approval. Apoquel has not been tested in dogs receiving some medications including some commonly used to treat skin conditions, such as corticosteroids and cyclosporine. Do not use in breeding, pregnant, or lactating dogs. Most common side effects are vomiting and diarrhea. Apoquel has been used safely with many common medications including parasiticide antibiotics and vaccines. For more information, please see the full prescribing information apoquel.com/pi. Apoquel indications for control of pruritis associated with allergic dermatitis and control of atopic dermatitis in dogs at least 12 months of age. Cytopoint has been shown to be effective for the treatment of dogs against allergic dermatitis and atopic dermatitis. Here are the references for today's video