Zinc-Responsive Dermatosis

What is it?

Zinc is a mineral needed for the immune system, thyroid function, and healthy skin, hair, and nails. True dietary zinc deficiency is rare, because good-quality dog foods contain plenty. There are two main forms. Type 1 occurs mostly in Alaskan breeds such as Siberian huskies and Alaskan malamutes, and also in Doberman pinschers and Great Danes; these dogs eat enough zinc but do not absorb it well, and flare-ups may follow stress, a heat cycle, or gut disease. Type 2 affects fast-growing large and giant-breed puppies, such as Great Danes, German shepherds, Labrador retrievers, standard poodles, and Dobermans, when supplements high in calcium or plant phytates bind zinc in the diet.

What signs should I watch for?

Look for crusts and scaling around the eyes, mouth, scrotum, and the edges of the lips, vulva, or prepuce, along with a dry, dull coat. Some dogs itch and some do not. Type 2 dogs may also develop thick crusts on the footpads, and severely affected dogs may lose appetite, become lethargic, or have enlarged lymph nodes.

How is it diagnosed and treated?

Blood and hair zinc levels are not reliable. Your veterinarian may suspect the condition from the pattern of lesions, check skin cytology for secondary bacterial or yeast infection, and confirm it with a skin biopsy. Treatment means making sure the food provides enough usable zinc, stopping supplements that block zinc absorption, and giving oral zinc, best absorbed when tablets are crushed and mixed with food. Improvement is often seen within a couple of weeks.

Can it be prevented, and what's the outlook?

• Feed a complete, balanced diet and avoid unneeded calcium or mineral supplements, especially for large-breed puppies.
• Many dogs, particularly Alaskan breeds, need lifelong supplementation and monitoring, but the outlook is good with treatment.