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Diagnosis and Treatment of Canine Atopic Dermatitis: 10 Tips for Vet Students

Posted by Cathy Barnette on November 15, 2021 at 10:27 AM
Cathy Barnette
Cathy Barnette is a practicing small animal veterinarian, freelance writer, and contributor to XPrep Learning Solutions. She is passionate about both veterinary medicine and education, working to provide helpful information to veterinary teams and the general public. In her free time, she enjoys spending time in nature with her family and leading a Girl Scout troop.

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IconVP02Regardless of where you end up practicing veterinary medicine, you are likely to see a fair amount of canine atopic dermatitis. If you practice in an allergy hotspot, this is especially true!

When I used to practice in the Charlotte, NC area, there were weeks when over half of my canine patients were presenting for skin issues. Given the prevalence of allergic dermatitis in dogs and the headaches inherent in explaining, diagnosing, and treating atopy, it’s important to feel comfortable with this condition. 

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Follow these ten tips to help your canine atopic dermatitis patients:

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1. Keep the “typical” clinical presentation of atopy in mind. 

While atopy can occur at any age, it’s most commonly diagnosed between six months and three years of age.1 In early stages, dogs may have pruritus without any visible skin lesions, though skin lesions often develop as the condition progresses. Skin lesions are most common on the face, pinnae, ventral abdomen, paws, and perineum. Atopy is often seasonal in nature, although indoor allergens (dust, dust mites, mold, etc.) may trigger year-round signs.

2. Make your diagnosis by excluding other conditions.

While a “typical” presentation may increase your suspicion of atopy, it’s important to rule out other differential diagnoses. Atopy is a diagnosis of exclusion. Check patients carefully for fleas and ensure that they are on effective flea prevention. Perform skin scrapes to rule out demodex. Consider skin biopsies if lesions suggest the possibility of other immune-mediated conditions. Perform a food trial if the signs are non-seasonal in nature. Think through other potential causes of your patient’s skin issues; rule these causes out before arriving at a diagnosis of atopy.

3. Don’t forget to rule out scabies!

While we often forget about or dismiss the possibility of scabies, this is a step that you must not skip. Skin scrapes are not reliable for diagnosing scabies. Instead, treat empirically with Revolution®, Simparica®, Bravecto®, or another effective treatment to rule out this condition.

4. Diagnose and treat secondary infections. 

Many dogs with atopic dermatitis develop secondary bacterial pyoderma or Malassezia infections of the skin. Skin cytology is a necessary component of the workup of an atopy suspect and should be performed regularly in patients with atopy.

5. Emphasize effective, year-round flea prevention. 

Dogs with atopy also tend to be highly reactive to flea bites. Therefore, it’s essential that the owners of atopic dogs understand the importance of effective, year-round flea prevention. Remember that product failures are relatively common with over-the-counter products. If a client insists that they are using an OTC product appropriately and their dog is still itchy, recommend a prescription veterinary flea preventative.

6. Understand the role of allergy testing in atopy.  

Allergy testing cannot be used to diagnose atopy. Intradermal allergy testing or blood allergy tests should only be performed once you have confirmed a diagnosis of atopy, in order to determine which allergens to include in hyposensitization therapy. (They can also offer additional benefits by suggesting environmental allergens that your client may wish to avoid.)

7. Set realistic expectations if you recommend hyposensitization. 

Many owners see “allergy shots” or immunotherapy as a surefire cure for atopy. In reality, however, the response to treatment is variable. Approximately 50% to 80% of treated dogs will experience an improvement in clinical signs and/or a reduction in the need for other medications within one year of beginning immunotherapy treatment.2 This means that 20 to 50% of treated dogs will show no improvement. Additionally, even dogs that show improvement may still experience clinical signs or require additional medication to control flare-ups. Hyposensitization can be valuable, but it’s important for owners of atopic dogs to have realistic expectations.

8. Prepare clients for ongoing management. 

Allergies are managed, not cured. Owners need to be prepared to experiment with a variety of therapies to see what works best for their dog, realizing that their dog’s pruritus may never be completely eliminated. Talk to clients about options like Apoquel® and Cytopoint®, but emphasize that there is no one-size-fits-all approach, and different dogs respond differently to medications. Some degree of trial and error is often needed to find the best treatment for a given dog. Antihistamines, medicated shampoos, and fatty acid supplements may also be beneficial, alone or in conjunction with other therapies. In severe flare-ups, even a brief course of corticosteroids may be necessary, although corticosteroids are not without risk and should be used sparingly.

9. Low-tech interventions can help. 

Many dogs are allergic to pollens and grasses that they encounter while outdoors. In these dogs, something as simple as wiping the dog’s feet and coat after outdoor walks can help decrease the amount of pollen that is brought into the home, reducing the dog’s overall pollen exposure. Owners can also keep their windows closed during allergy season, change air filters frequently, wash their dog’s bedding frequently, and vacuum regularly to limit dust and dust mite exposure.

10. Consider a hypoallergenic diet. 

While atopy is recognized as a distinct entity from food allergies, there can be some overlap. Switching atopic dogs to a hypoallergenic diet can help maintain their overall allergen exposure at a level that is below their “allergic threshold.” 

Atopy can be a challenging condition to explain to owners because the diagnosis and treatment are often uncertain… at least compared to other conditions that we commonly treat in veterinary medicine. Hopefully, with the help of these tips, you can keep your thoughts organized as you guide your clients through the successful diagnosis and treatment of this relatively common condition. 

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References

  1. Banovic, F. (2018). Canine Atopic Dermatitis: Updates on Diagnosis and Treatment. Today’s Veterinary Practice. Retrieved from: https://todaysveterinarypractice.com/canine-atopic-dermatitis-updates-diagnosis-treatment/
  2. Olivry, T., DeBoer, D. J., Favrot, C., Jackson, H. A., Mueller, R. S., Nuttall, T., Prélaud, P., & International Task Force on Canine Atopic Dermatitis (2010). Treatment of canine atopic dermatitis: 2010 clinical practice guidelines from the International Task Force on Canine Atopic Dermatitis. Veterinary dermatology, 21(3), 233–248. Retrieved from: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-3164.2010.00889.x#support-information-section

Topics: Dermatology, Atopic Dermatitis

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