Zinc-responsive dermatosis

19 Zinc-responsive dermatosis




INITIAL PRESENTATION


Crusting and scaling over pressure points.



INTRODUCTION


There are various canine nutrient-responsive dermatoses described, including vitamin A- and zinc-responsive dermatoses and essential fatty acid deficiency. These conditions may be associated with dietary deficiencies or imbalances, or genetic defects resulting in an inability to absorb nutrients. With the ready availability of good quality diets over the last two decades, conditions resulting from dietary deficiency are uncommon to rare but can still occur. This report describes a case of zinc-responsive dermatosis associated with the feeding of a poor quality, predominantly cereal-based diet.




CASE PRESENTING SIGNS


A 3-year-old, entire male Border collie was presented with crusting and pruritus.



CASE HISTORY


The history in zinc-responsive dermatoses will tend to vary depending on the breed of dog affected (see ‘Aetiopathogenesis’ section). Syndrome II zinc-responsive dermatosis most commonly affects puppies fed zinc-deficient diets but a change of diet or gastrointestinal disease can result in symptoms in an adult dog. One study from North America showed that most Northern breed dogs developed lesions during the winter months. Initial lesions tend to be erythematous, with subsequently alopecia, crusting and scaling over pressure point areas and areas of skin trauma. Affected dogs are variably pruritic.


The history in this case was as follows:


• The dog had been acquired by the owner as a puppy at 2 months of age.

• There was no previous history of skin disease.

• A few months previously, prior to the onset of skin lesions, the patient had developed persistent diarrhoea which had resolved with a change from tinned dog food to a cereal-based diet.

• Within a few weeks of the change of diet, the dog had developed a pruritic, crusting scrotal dermatitis. In addition, crusting lesions had developed around the eyes and lips.

• The dog was slightly depressed, although appetite and thirst were unaffected.

• Antibacterial therapy using cefalexin at a dosage of 20 mg/kg b.i.d. had resulted in no improvement.

• There were no other pets in the household.

• There was no evidence of zoonosis.


CLINICAL EXAMINATION


Zinc-responsive dermatosis predominantly affects areas of the skin subject to ‘microtrauma’, such as the perioral and periocular skin, the elbows, hocks and footpads. The nasal planum may be affected. Early lesions are erythematous with subsequent alopecia, crusting and scaling. Erosions underlie the crust.


In this case:


• The patient was afebrile.

• There were well-demarcated, focal areas of crusting and partial alopecia over the perioral (Fig. 19.1) and periocular skin. The crusts were grey in colour.

• Nail folds, interdigital areas (Fig. 19.2) and the caudal aspects of both hock joints (Fig. 19.3) were similarly affected. Elevation of crusts revealed erosions and exudation (Fig. 19.4).

• There was mild footpad hyperkeratosis.

• There were thick, black-coloured crusts adherent to the skin over the scrotum.

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Figure 19.1 Perioral crusting.


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Figure 19.2 Crusting and scaling over the interdigital skin.


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Figure 19.3 Crusting and scaling over the hocks.


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Figure 19.4 Erosions revealed after crust removal.




DIFFERENTIAL DIAGNOSES


This was a crusting dermatosis affecting primarily pressure point areas. The lesions, in association with a history of being fed a high cereal diet, were suggestive of a zinc-responsive dermatosis, but other possible differentials included:


• Demodicosis

• Sarcoptic mange

• Dermatophytosis

• Pyoderma

• Malassezia dermatitis

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Sep 3, 2016 | Posted by in SMALL ANIMAL | Comments Off on Zinc-responsive dermatosis

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