Zinc is a trace mineral that is found in virtually every cell in the body. Adequate zinc levels are absolutely essential to good health. Zinc is a component of many vital proteins. It is a part of over 200 enzymes and functions in more enzymatic reactions than any other mineral. Zinc is also required for proper action of many hormones, including insulin, growth and sex hormones. Zinc is especially important to proper immune function, wound healing, sensory function, sexual function, and skin health. A deficiency in this mineral can lead to zinc-responsive dermatosis, which results from either an absolute or relative deficiency in zinc and is primarily seen in fast-growing giant breeds fed inadequate diets rich in soya and cereals. Kittens fed soy protein-based diet may also have poor coat characterized by thinning, slow hair growth, scaliness of the skin, and ulceration. Other causes of zinc deficiency are chronic or acute diarrhea, kidney disease, liver disease, or diabetes.
Two forms of the disease exist. The heritable form affects the Alaskan Malamute and Siberian Husky. The acquired form affects growing puppies fed zinc-deficient or oversupplemented diets. The disease is characterized by inflammation, hair loss, dull coat, scales, and crusts that primarily affect the head. Zinc-responsive dermatosis is diagnosed based on clinical examination, laboratory testing for zinc levels (skin biopsy), and dietary history. Zinc supplementation with oral zinc sulfate is the treatment of choice, which may be required for life in the familial form of the disease. In other individuals, the supplementation is provided only until the skin signs have resolved.
Best dietary sources of zinc are red meat, shellfish, fish, kelp, whole grains, and legumes. However, zinc in plant foods is less available because it binds to phytic acid. Soy contains more phytic acid than any other grain, and because phytic acid impairs absorption of most minerals, especially calcium, zinc, magnesium, and iron, diets rich in soy can strip the body of these minerals. There is eight times the level of phytic acid in wholemeal flour as compared with white flour. However, when flour is used to make bread, phytase (the enzyme that breaks down phytic acid) present in yeast destroys up to one-third of the phytic acid content of wholemeal flour and nearly all that in white flour.
- Richard G. Harvey, P. J. McKeever A Colour Handbook of Skin Diseases of the Dog and Cat
- Canine zinc-responsive dermatosis. Colombini S. Veterinary Teaching Hospital and Clinics, School of Veterinary Medicine, Louisiana State University, Baton Rouge, USA.
- Robin J. Harman. Handbook Of Pharmacy Health Education