Zinc-Responsive Dermatosis in Dogs

What is zinc-responsive dermatosis?

Zinc-responsive dermatosis in dogs is a skin condition that results from zinc deficiency in the body. Zinc is a mineral that is important for 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 dogs, 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 with zinc deficiency experience stunted growth, diarrhea, crusted and cracked footpads, and multiple infections. These puppies do not respond well 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. Zinc-responsive dermatosis (skin abnormalities) in dogs can be divided into three categories:

Type 1 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, Great Dane, and other breeds. These dogs typically consume a diet with an adequate zinc content, so their skin disease appears to be due to inadequate intestinal absorption. Zinc-responsive dermatosis may be linked to a stressful event, estrus (heat), or severe gastrointestinal disease.

Associated skin lesions include crusts and scaling around the eyes, mouth, scrotum, and the transition areas between skin and mucous membranes like the lips, vulva, or prepuce. These dogs may also develop a dry, dull haircoat and may or may not be itchy.

Type 2 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. This condition is directly related to dietary supplements that interfere with zinc absorption by binding with zinc, specifically phytates (plant-based antioxidants) and calcium.

These dogs may have lesions like the Alaskan breeds, but they may also have thick crusts on their foot pads. If severely affected, dogs may have poor appetite, lethargy, and enlarged lymph nodes.

How is zinc-responsive dermatosis diagnosed?

It would seem that measuring zinc concentration in the blood or hair would diagnose a zinc-responsive dermatosis, but many dogs have low concentrations of zinc normally, so this is not typically used.

Your veterinarian may make a presumptive diagnosis based on the type and pattern of skin lesions and other signs. They may also perform skin cytology (examine cells under a microscope) to check for secondary bacterial or yeast infections. Definitive diagnosis requires skin biopsy: surgical removal of representative samples of tissue from lesions. The biopsy is examined under a microscope by a pathologist who can recognize the specific patterns that indicate the disease.

How is zinc-responsive dermatosis treated?

Once a diagnosis of zinc-responsive dermatosis has been made, the first step in treatment is to ensure the dog’s food contains adequate levels of bioavailable zinc, which may mean changing diets. Likewise, it is important to consider any nutritional supplements being given to the dog that may interfere with zinc absorption.

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