Small Animal Dermatology Q&A 22

This question was provided by Manson Publishing as part of the OVAL Project. See more small animal dermatological questions

A 3-year-old female Siberian husky dog is presented for the complaint of ‘crusties’. The owner reports the dog has pruritic crusty lesions on the face and ears. On dermatological examination, the lesions around the eyes are symmetrical, and similar lesions are present on the ear margins, chin, ears, footpads, and pressure points. The skin is thickened and hyperkeratotic crusting is present. The dog is healthy otherwise. The dog is fed a complete and balanced diet. Two littermates, owned by other people, have similar lesions.

Question	Answer		Article
What is the most likely diagnosis and how should this be confirmed?	Zinc-responsive skin disease. The signalment, clinical signs, and affected littermates are compatible with zinc deficiency. The diagnosis could be confirmed by skin biopsy. The key finding is diffuse parakeratosis, especially of the follicular epithelium. Serum and hair concentrations of zinc may be abnormal, but it is difficult to find a reliable laboratory to do the testing. Siberian husky, Alaskan malamute and some bull terrier dogs have an inherited defect that decreases their capability to absorb zinc from the intestines. This is called syndrome I of zinc-responsive skin diseases. Syndrome II occurs in rapidly growing dogs that are fed zinc deficient diets high in phytates or minerals (e.g. calcium), or diets oversupplemented with minerals and vitamins that interfere with zinc absorption.		Link to Article
How should the dog be treated, and how soon would resolution of clinical signs be expected?	This dog needs 1 mg/kg of elemental zinc each day. The most commonly used supplements are zinc sulfate (10 mg/kg/day), zinc gluconate (5 mg/kg/day), or zinc methionine (1.7 mg/kg/day). Feeding a dog food with ‘zinc’ is not adequate nor are vitamin supplements containing zinc. Some Siberian husky dogs do not respond to oral supplementation and may require intravenous injections of zinc sulfate solutions (10–15 mg/kg) weekly for at least 4 weeks, and then every 1–6 months thereafter. Therapy is life-long. Improvement in clinical signs is usually evident within a few weeks. After the diagnosis, the lesions should be hydrated and the crusts soaked off.		Link to Article
What endocrine disease may play a role in the pathogenesis of this disease?	Thyroid hormones are important in the absorption and utilization of zinc. Dogs that develop spontaneously occurring hypothyroidism may develop clinical and histological signs of zinc-responsive skin disease. These dogs may fail to respond to zinc supplementation if their hypothyroidism is not diagnosed and treated.		Link to Article