Multimodal Therapy is Best: Atopic Dermatitis with Environmental and Food Allergens: Dobby

Dobby was surrendered 4 years ago (July 2012) to a rescue organization in Houston because of intractable skin problems and chronic loose stool with increased frequency of bowel movements (10 per day, soft). On presentation, Dobby was very itchy (9/10 on Visual Analog Score for pruritus) and clinical examination revealed erythema and a waxy crust present on the concave surface of his pinnae, within his facial folds, and ventrally extending from the axillae down the chest to the abdomen and medial thighs. Both ear canals contained a thick waxy yellow exudate and the ear canals were very itchy.

Skin scrapings were negative for Demodex and sarcoptic mites, and there was no pinnal pedal reflex. Skin cytology showed 4+ cocci and 4+ yeast, compatible with bacterial and yeast overgrowth. A serum allergy test had already been performed and the dog showed positive reactions to numerous pollens, both house dust mites, human dander, Staphylococcus, and Malassezia; we anticipated no new results by intradermal testing so it was not performed. We instituted a comprehensive multimodal treatment plan for this dog. For this infections, he was given an injection of 8 mg/kg cefovecin subcutaneously, and started on an oral course of fluconazole 5 mg/kg for 14 days. He would be bathed 3x weekly with a chlorhexidine/climbazole shampoo-containing phytosphingosine. Flea and heartworm prevention was started with topical imidacloprid/moxidectin, which was to be administered initially every two weeks, as he was bathed frequently and this protocol would help rule out the possibility that he was co-infected with scabies. He also was given 4 mg methylprednisolone orally once daily for 14 days, then 1 tablet every other day (oclacitinib was not yet available). His ears were flushed with a micellar phytosphingosine solution, and gentamicin/miconazole/hydrocortisone aceponate (EasOtic, Virbac) administered once daily for 5 days per label instructions. A sublingual allergy vaccine was ordered from Heska, and was started 5 days later; he was given 2 drops under the tongue twice daily. To address the possibility of food allergy as a contributing factor to the diarrhea and itch, he was started on an exclusive diet of a hydrolyzed soy diet. Fecal examination was negative for endoparasites.

Recheck two weeks later showed that cytologies were negative for cocci and only scant yeast were found; his itch was reduced to 5/10. The ears were completely normal. One month later, all skin infections were resolved, and the pruritus was reduced to 3/10. Bathing was reduced to twice weekly, the allergy vaccine was continued, and the glucocorticoid dose reduced to 2 mg methylprednisolone 3x weekly. The stools were still loose but the frequency had decreased to 4 times daily from probiotics were then started orally (Fortiflora, Purina) and 2 weeks later stools were normal; he had no flare of itch when the flavored probiotic was added to his diet. At that time, he was challenged with a commercial diet containing chicken and flared with gastrointestinal signs. Subsequent challenge with chicken showed that it was the offending allergen and he currently eats a commercial lamb and potato diet. No other food triggers were identified, but exposure to chicken-based foods or treats re-exacerbates the gastrointestinal disease.

Three months later, Dobby was doing well; he still had some itch but had not relapsed with infection. We reduced bathing to once weekly and continued 2 mg methylprednisolone twice weekly and the allergy vaccine twice daily.

Seven months later, the dog was clinically normal, with no relapse of infection, and minimal itch; steroids had been discontinued 2 weeks previously with no relapse in itch. Bathing was continued once monthly, his topical heartworm/flea control product applied monthly, and his allergy vaccine continued twice daily.

Over the last 4 years, this dog flares with itch and mild pyoderma each fall and each winter, in association with pollen spikes. Cefovecin has been administered twice a year, one injection, each time and the pyoderma has responded well. After the last outbreak a culture and sensitivity was performed and the Staphylococcus pseudintermedius isolated found to be sensitive to multiple antibiotics. Maintenance bathing is done monthly and his allergy vaccine has been continued once daily for the long term. When Apoquel became available, it was used at 0.6 mg/kg once daily for 5–7 days to put him back into remission when he had flares; he is very response to this medication and for him it appears even more effective than glucocorticoids. Dobby struggled with frequent bouts of itch in the fall of 2015, due to the severe and constant pollination. When it became available, we chose canine atopic dermatitis immunotherapeutic, a fully canonized monoclonal antibody against IL-31, given subcutaneously at 2 mg/kg. Dobby experiences 6 weeks of relief following his injections.

Complicated Itch in a Pup: Sasha

Sasha is a mixed-breed dog left at our clinic; we estimated her age at 4 months. She was intensely itchy (10/10) and had extensive alopecia and erythema, with a positive pinnal pedal reflex. Skin scrapings were positive for scabies mites and eggs, and we made a diagnosis of scabies. Skin cytology showed occasional cocci and yeast. The use of selamectin and bathing resulted in negative scrapings but the itch remained.

A food trial was started to determine if this dog had food allergy. She was fed a rabbit and potato diet for 6 weeks, with only partial improvement in her itch. We estimated that she was about 40-50% improved after treatment for scabies and the food. Challenge with a commercial diet exacerbated her itch and single food challenges performed weekly confirmed a reaction to chicken. She was able to eat a prescription fish and potato diet for maintenance.

At this point the dog was about 8 months of age, and she required steroids to keep comfortable in spite of flea control and diet control. We stopped the steroids for one week and her itch increased to 5/10. We performed an intradermal test as well as a serum allergy test and discovered that she was profoundly allergic to several trees, weeds, and grasses. A sublingual allergy vaccine was started based on these results and she was given 2 drops twice daily. Glucocorticoids were administered daily for the first month, then the dose was dropped to alternate day for the next month. We did not use oclacitinib as this dog was 8 months of age, and one year is the recommended age at which to use this drug. Three months after starting the allergy vaccine we were able to reduce the glucocorticoids to twice weekly, and by six months, we were able to stop the glucocorticoids with no relapse in itch. This dog was successfully maintained on her sublingual allergy vaccine, her fish and potato diet, and topical flea control for 3 years with no relapse. We decided to stop the allergy vaccine and see how she did. She continued to do well with no relapse in itch for the next year and half, after which she moved to Colorado! She is now approximately 7 years old and doing well.

Important Points

1.  Atopic dermatitis is a complex disease. Favrot's criteria can be useful.

2.  Age of onset: 3 years or less

3.  Mostly indoors

4.  Alesional pruritus at first

5.  Affected front feet

6.  Affected pinnae

7.  Unaffected ear margins

8.  Unaffected dorsolumbar areas (unless concurrent flea allergy is present).

9.  Multimodal management is key to success in the management of this disease.

10.  Avoid what can be avoided (fleas, food triggers).

11.  Immunotherapy to change the abnormal immune response

12.  Control infections with bathing and the judicious use of anti-infective medications.

13.  Repair the skin barrier with good nutrition and topical lipids.

14.  Control itch and inflammation.

References

1.  Hensel P, Santoro D, Favrot C, Hill P, Griffin C. Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification. BMC Vet Res. England; 2015;11:196.

2.  Olivry T, DeBoer DJ, Favrot C, Jackson HA, Mueller RS, Nuttall T, Prélaud P, International Committee on Allergic Diseases of Animals. Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA). BMC Vet Res. England; 2015;11:210.

3.  Saridomichelakis MN, Olivry T. An update on the treatment of canine atopic dermatitis. Vet J. England; 2016;207:29–37.

4.  Cosgrove SB, Wren JA, Cleaver DM, Martin DD, Walsh KF, Harfst JA, Follis SL, King VL, Boucher JF, Stegemann MR. Efficacy and safety of oclacitinib for the control of pruritus and associated skin lesions in dogs with canine allergic dermatitis. Vet Dermatol. England; 2013;24(5):479–e114.

5.  Cosgrove SB, Cleaver DM, King VL, Gilmer AR, Daniels AE, Wren JA, Stegemann MR. Long-term compassionate use of oclacitinib in dogs with atopic and allergic skin disease: safety, efficacy and quality of life. Vet Dermatol. England; 2015;26(3):171–179,e35.

6.  Cosgrove SB, Wren JA, Cleaver DM, Walsh KF, Follis SI, King VI, Tena J-KS, Stegemann MR. A blinded, randomized, placebo-controlled trial of the efficacy and safety of the Janus kinase inhibitor oclacitinib (Apoquel®) in client-owned dogs with atopic dermatitis. Vet Dermatol. England; 2013;24(6):587–597,e141-2.

7.  Bexley J, Nuttall TJ, Hammerberg B, Fitzgerald JR, Halliwell RE. Serum anti-Staphylococcus pseudintermedius IgE and IgG antibodies in dogs with atopic dermatitis and nonatopic dogs. Vet Dermatol. England; 2013;24(1):19–24.e5–6.

8.  Morales CA, Schultz KT, DeBoer DJ. Antistaphylococcal antibodies in dogs with recurrent staphylococcal pyoderma. Vet Immunol Immunopathol. The Netherlands; 1994;42(2):137–147.

9.  Oldenhoff WE, Frank GR, DeBoer DJ. Comparison of the results of intradermal test reactivity and serum allergen-specific IgE measurement for Malassezia pachydermatis in atopic dogs. Vet Dermatol. England; 2014;25(6):507–511,e84-5.

10. Farver K, Morris DO, Shofer F, Esch B. Humoral measurement of type-1 hypersensitivity reactions to a commercial Malassezia allergen. Vet Dermatol. England; 2005;16(4):261–268.

11. Morris DO, DeBoer DJ. Evaluation of serum obtained from atopic dogs with dermatitis attributable to Malassezia pachydermatis for passive transfer of immediate hypersensitivity to that organism. Am J Vet Res. United States; 2003;64(3):262–266.

12. Chen T-A, Halliwell REW, Pemberton AD, Hill PB. Identification of major allergens of Malassezia pachydermatis in dogs with atopic dermatitis and Malassezia overgrowth. Vet Dermatol. England; 2002;13(3):141–150.

13. Nuttall TJ, Halliwell RE. Serum antibodies to Malassezia yeasts in canine atopic dermatitis. Vet Dermatol. England; 2001;12(6):327–332.

14. Dell DL, Griffin CE, Thompson LA, Griffies JD. Owner assessment of therapeutic interventions for canine atopic dermatitis: a long-term retrospective analysis. Vet Dermatol. England; 2012;23(3):228–e47.