What is Zinc-Responsive Dermatosis?
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 dogs, including:
- Lack of protection from infection
- Abnormal iodine metabolism
- Interference with normal cell developments 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.
It is directly related to dietary supplements that interfere with zinc absorption by binding with the mineral, specifically, phytates (plant-based antioxidants) and calcium. These dogs may have lesions that are similar to 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.
Type 3 Zinc-responsive dermatosis is referred to as “generic food disease”. Dogs who are reported with this form of skin disease, are often eating dog foods that do not meet National Research Council nutritional requirements, and contain inadequate levels of zinc that are also poorly bioavailable.
How is zinc-responsive dermatosis diagnosed?
Measurement of zinc levels is difficult to diagnose but checking a dog’s clinical and nutritional history, along with a physical examination and a skin biopsy are 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 to make sure that the dogs’ food contains adequate levels of bioavailable zinc. This may mean changing diets. 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 is 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 weeks. It is best to plan for lifetime supplementation and management.