Zinc-Responsive Dermatosis in Dogs

My dog was just diagnosed with zinc-responsive dermatosis. I thought he had a skin infection when I took him to the veterinarian. How does this disease happen?  What is involved?

The mineral zinc plays an important role in many substances in the canine body including enzymes, proteins, and hormones. Zinc is also important for immune system function and thyroid function. Zinc-deficiency can result in many problems for the dog including:

• Lack of protection from infection
• Abnormal iodine metabolism
• Interference with normal cell development including wound healing, and replacement of intestinal lining cells, skin cells, hair, and nails
• Interference with normal sexual function (important in breeding animals)

Puppies affected with zinc-deficiency experience stunted growth, diarrhea, crusted and cracked footpads, and multiple infections. These puppies do not respond to zinc supplementation, and usually die or are euthanized.

True zinc-deficiency is rare and is thought to result from a malabsorption of zinc in the small intestine, as there is plenty of zinc that is highly bioavailable (easily absorbed) in good quality dog foods.

The zinc-responsive dermatoses (skin abnormalities) in dogs can be divided into three categories:

Type 1:

This zinc-responsive dermatosis occurs most often in the Alaskan breeds like the Siberian Husky and the Alaskan Malamute, although it has also been reported in the Doberman Pinscher and Great Dane. These individuals typically consume a diet with an adequate zinc content, so their skin disease appears to be due to inadequate intestinal absorption. The dermatosis may be linked to a stress event, estrus (heat), or severe gastrointestinal disease. The associated skin lesions include crusts and scaling around the eyes, mouth, scrotum, and the transition areas between skin and a mucous membrane like the lips, vulva, or prepuce. These dogs may also develop a dry, dull haircoat and may or may not be itchy.

Type 2:

This zinc-responsive dermatosis is primarily seen in fast-growing large and giant breed dogs including Great Danes, German Shepherds, Labrador Retrievers, Standard Poodles, and Doberman Pinschers. It is directly related to dietary supplements that interfere with zinc absorption by binding with the mineral, specifically phytates (plant-based anti-oxidants) and calcium.

These dogs may have lesions similar to the Alaskan breeds, but may also have thick crusts on their foot pads. If severely affected, dogs may be inappetant (uninterested in eating) and lethargic, and they may also have enlarged lymph nodes.

Type 3:

The third type of zinc-responsive dermatosis is referred to as “generic food disease.”  The dogs who were reported with this form of skin disease were eating dog foods that did not meet National Research Council nutritional requirements, containing inadequate levels of zinc that was also poorly bioavailable.

My dog had a skin biopsy in order to make this diagnosis. Is this a common practice?

Measurement of zinc levels in the blood or hair is difficult, making the dog’s clinical and nutritional history, a physical examination, and a skin biopsy important strategies for diagnosis.

How is zinc-responsive dermatosis treated?

Step one in treatment once a diagnosis of zinc-responsive dermatosis has been made is make sure that the dog’s food contains adequate levels of bioavailable zinc. This means eliminating generic dog food!  Likewise, it is important to consider any nutritional supplements that are being given that may interfere with zinc absorption.

Zinc is available as an oral supplement, and may be best absorbed if tablets are first crushed and then mixed with food. Skin improvements in dogs with zinc-responsive dermatosis may be seen within just a couple of weeks. It is best to plan for lifetime supplementation/management.