Zinc-Responsive Dermatosis in Dogs

A rare scaling skin disorder, zinc-responsive dermatosis is the result of zinc deficiency, zinc malabsorption or incorrect utilization of zinc. Zinc is imperative for over 300 enzymes, structural proteins and hormones. It is critical for numerous biological functions, to include regulating the immune system’s response, cell replication and regenerating the intestinal mucosa, adjustment in regards to keratogenesis and the healing of wounds, maintaining typical reproductive function, turning over epithelial cells that are needed to keep skin, hair and nails healthy and the sharpness of the dog’s taste and smell. When zinc deficiency occurs, certain immune responses are reduced (those handled by T cells) and antibody production is decreased.

Zinc-responsive dermatosis may occur as a result of several causes and can lead to redness, scaling, crusting and hair loss among other symptoms.

In both Syndrome I and Syndrome II, redness (as a result of congestion in the capillaries in the lower layers of the skin) will be present at the mucocutaneous junction and pressure points. In addition, scaling, crusting, hair loss, pyoderma and lichenification mainly involving your dog’s head can occur.

Should your dog experience a severe case of either syndrome, you may see the following:

• Lack of interest in eating
• Stunted growth
• Lethargy

Types

Several clinical presentations of zinc-responsive dermatosis are seen in dogs:

Syndrome I - Usually only found in northern breeds like Siberian Huskies and Alaskan Malamutes; this condition is inherited and results in something going awry in the absorption or metabolization of zinc

Syndrome II - Occurs in quickly growing puppies of a larger breed that ingest a diet that is high in phytate and deficient in zinc or a diet that has parts that can inhibit zinc being absorbed

Generic Dog Food Disease - Scaling and crusting as developed in some dogs after being fed a generic dog food for two to four weeks; these foods did not meet the National Research Council requirements and did not have an optimal level of zinc (in addition to the skin symptoms, puppies with this condition had fever, depression and swollen lymph nodes)

There are also hereditary zinc deficiencies that can occur, for example:

• Nasal hyperkeratosis in Golden Retrievers
• Congenital follicular parakeratosis in Rottweilers and Siberian Huskies

Syndrome I is the result of a genetic defect in your dog’s intestinal absorption. Syndrome II occurs when large-breed puppies consume a diet that is high in phytate and deficient in zinc; or the diet may include things that can inhibit zinc absorption, leading to the deficiency. Generic dog food disease can occur when generic dog food that does not include the appropriate amount of zinc is fed to your dog for as little as two weeks.

Should you notice any unusual symptoms in your dog, you will want to visit your veterinarian. Your dog will receive a complete physical examination and your veterinarian may choose to take samples of his blood and skin for further analysis. Zinc-responsive dermatosis can be diagnosed by looking at affected skin cells under a microscope as well as reduced amounts of zinc in the dog’s blood and his response to treatment. It has been found that low amounts of zinc in the serum and hair of your dog is not conclusive and must be seen in conjunction with a positive response to treatment.

Conditions that your veterinarian will look to rule out include:

• Lethal acrodermatitis (seen in Staffordshire Bull terriers)
• Demodectic mange
• Vitamin A-responsive dermatosis
• Lupus erythematosus
• Malassezia dermatitis

Supplementing zinc and retinoid is typically successful for dogs experiencing zinc-responsive dermatosis. Zinc may be administered as an oral supplement on a daily basis and should the case be severe, your veterinarian may recommend your dog receive an injection of zinc sulfate. Your dog should undergo treatment for a month to see how he is responding to treatment. Should it not lead to improvement, your veterinarian may want to increase the dose by 50%. Antimicrobial therapy may be recommended as well as regular bathing with keratolytic shampoos like sulfur and salicylic acid.

Dogs with Syndrome I have a fair prognosis though it is recommended that they not breed out of concern for passing on the condition. An excellent prognosis is expected for dogs experiencing Syndrome II. Symptoms will usually resolve after a few weeks of your dog receiving zinc supplements. 

Your veterinarian will likely recommend a follow up appointment so that he can determine whether treatment is effective and make treatment changes if necessary. Working closely with your veterinarian is important to ensure the best outcome for your dog.