Zinc Responsive Dermatosis in a French Bulldog

French bulldog dermatosis case reveals zinc deficiency causing facial crusting and ear lesions. Learn about diagnostic approaches, zinc methionine supplementation protocols, and managing secondary bacterial pyoderma effectively.

Rebecca Mount, DVM, DACVD

Dermatology for Animals, Albuquerque, NM

 June 2025

History

Reggie” is a 6 month old MI French Bulldog with progressive thick crusting on the pinnae and face. The owner reported progressive crusting of the face and ears which developed at 8 weeks of age. The crusting progressed over six months. The owner reported a pruritus level of 7/10. Pruritus was mostly directed at the crusted lesions, but generalized pruritus was not noted. Treatment with a topical emollient and oral antibiotics (amoxicillin-clavulanate potassium) had provided little relief or improvement. Treatment with an isoxazoline for any potential parasitic dermatoses did not provide any improvement. The owners noted the dam of Reggie’s litter was diagnosed with zinc responsive dermatosis.

At the initial presentation the dog was still intact as the primary veterinarian wanted the skin condition managed prior to surgery. No other health issues were noted. The dog was current on vaccinations and on regular flea/tick and heartworm prevention. The pet was feed a commercial, over the counter, lamb diet.

Exam

Marked, thick, friable golden hyperkeratosis was noted on the pinnal margins and concave pinnae.  Otoscopic exam showed minimal erythema and scant debris. An anatomical stenosis prevented visualization of the tympanic membrane AU. On the face and muzzle there were numerous adherent, thick serous plaques with erosion/ulceration noted when the crust was lifted. The crusting of the face did not appear to extend to the nasal planum or lip margins.  The rest of the dermatologic exam was unremarkable.

Diagnostics

Initial diagnostics included cytology. Cytology of  the crusting on the concave pinnae revealed 1-2 Malassezia in most oil fields and 2+ coccoid bacteria. Cytology of the hyperkeratosis of the face folds revealed 3+ coccoid bacteria and numerous large clumps of Malassezia.

Measuring serum zinc levels can be difficult and is not generally considered an effective way to diagnose a zinc responsive dermatosis or evaluate response to supplementation.

Biopsy samples for histopathology are recommended for confirming zinc responsive dermatosis. The most prominent histological findings of zinc responsive dermatosis is marked parakeratosis of the epidermis and follicular epithelium. Acanthosis and perivascular inflammation can also be seen.

Assessment

Zinc responsive dermatosis with secondary bacterial pyoderma and Malassezia dermatitis

Treatment Plan

There are several available formulations for supplementing zinc including: zinc methionine, zinc gluconate, and zinc sulfate. Dosing depends on the formulation used.

The patient was started on a commercial zinc methionine supplement (NutriVed ZinPro) at 1 and ½ tablets (22.5 mg of zinc) every 24 hours for the zinc responsive dermatoses. Side effects of zinc supplementation can include gastrointestinal upset, especially with certain formulations. The owners were also recommended to start a grain free diet as plant phytates in food can bind to zinc and reduce bioavailability.

To address the secondary infection an oral antifungal (ketoconazole 5mg/kg PO every 24 hours for 20 days) and clindamycin (11mg/kg PO every 12 hours for 20 days) were prescribed. Additionally, a topical antibacterial/antifungal wipe was recommended for maintenance therapy.

Follow-up

The patient was seen for a one month follow up. The pet was on an over the counter grain free lamb diet and  daily zinc methionine (NutriVed ZinPro). Reggie completed the antimicrobial therapy and clearance of secondary infection resulted in improvement in pruritus levels, but limited improvement in the crusting.  Based on the persistence of the crusting, addition of oral steroids (methylprednisolone 0.5 mg/kg every 24 hours tapered to every 48 hours) was recommended to help with gastrointestinal absorption of the zinc.  Steroids increase production of metallothionein which can help with zinc regulation and absorption. We also recommended that the owners crush the zinc tablets to help with absorption.

The patient presented for a recheck 6 months after the initial diagnosis.  On physical exam there was marked improvement of the crusting on the pinnae with mild persisting alopecia where thick hyperkeratosis were previously noted on the margins. The crusting on the face had resolved with persistent erythema of the face folds and scant reddish brown debris. The patient had been neutered since the initial exam. The steroids were reduced to twice weekly as flares with recurrent hyperkeratotic crust were noted when steroids were completely discontinued.

Discussion

Zinc responsive dermatosis is a cutaneous manifestation of decreased systemic zinc. Cutaneous lesions include erythema, alopecia, crusting, and scaling. Lesions most commonly affect sites of friction, paw pads,  the distal limbs, and  mucocutaneous junctions. The hair coat is often dull. In some cases, in addition to cutaneous lesions, weight loss, delayed wound healing, conjunctivitis, keratitis, and lymphadenopathy may be seen concurrently.

There are two types of zinc responsive syndromes: syndrome I and syndrome II:

Syndrome I is most common in Northern breeds and results from a suspected genetic defect in intestinal absorption of zinc. Other breeds affected by this syndrome are Bull terriers, Doberman pinschers, and Pharaoh hounds.  Skin lesions generally develop in young dogs despite being feed a nutritionally balanced diet. The lesions are variably pruritic. Due to the thick crusting affected dogs are more prone to developing secondary pyoderma or Malassezia dermatitis. Most of these cases require long term or life long zinc supplementation. In rare, severe cases intravenous supplementation is necessary.  Additionally, some cases as noted with Reggie, require the concurrent use of oral steroids to help with zinc absorption. Finally, since plant phytates can bind zinc, avoidance of diets high in plant phytates or use of phytase may help improve the availability of zinc in the diet.

Syndrome II is most commonly seen when rapidly growing puppies or young dogs are feed diets with low zinc levels or with high levels of phytates or calcium. Over-supplementation with minerals and vitamins can also reduce zinc levels in the diet. Finally, this syndrome can be seen in dogs with chronic enteritis or diarrhea resulting in impaired intestinal zinc absorption.  The clinical signs are similar to those noted for syndrome I. Syndrome II cases have been reported in Grate Danes, Doberman pinschers, beagles, Boston terriers, German shepherds, and many other breeds. Treatment for syndrome II requires dietary correction +/- zinc supplementation. If the dietary causes are adequately managed,  long term supplementation is not generally necessary for syndrome II.

The French bulldog is not a classically predisposed breed for zinc responsive dermatosis. However,  there seems to be an increase in the number of French bulldogs affected with thick crusted lesions clinically consistent with zinc responsive dermatitis. A recent abstract found 16 affected French bulldogs with clinical and histological signs suggestive of zinc responsive dermatosis. Most of the reported cases responded to zinc supplementation which further supports that zinc responsive dermatosis may be more prevalent in this breed than previously noted.

Overall, the prognosis for zinc responsive dermatitis is good pending response to therapy.

References

1. White, SD., Bourdeau, P., Rosychuk, RA. , et al. Zinc-responsive dermatosis in dogs: 41 cases and literature review. Veterinary Dermatology. 2001; 12(2):101-109.
2. Dubin, R., Keating, K., Rosenkrantz W. (2025) Parakeratotic hyperkeratosis of the pinnae in sixteen French bulldogs. In the proceeding of the North American Veterinary Dermatology Forum 2025. Abstract number 53.
3. Scott, D.W., Miller Jr, W.H., & Griffin, C.E. (2013). Muller and Kirk’s Small Animal Dermatology (7^th). Elsevier, pg. 689-694