UNDERSTANDING ZINC DEFICIENCY IN SIBERIAN HUSKIES

When her Siberian Husky developed what appeared to be a skin infection, Kathy Stryeski, D.V.M., of Cream Ridge, N.J., tried antibiotics and steroids. Neither helped. Finally, she discovered that her dog suffered from zinc-responsive dermatosis due to a zinc deficiency.

Stryeski also learned that zinc deficiency is not uncommon in Siberian Huskies, or for that matter in “Alaskan” breeds such as the Samoyed and the Alaskan Malamute. Compared to other breeds, these breeds have a significantly higher risk of zinc deficiency, even if they are fed a nutritionally balanced dog food.¹ “These breeds have a recessive genetic trait that affects zinc absorption,” says Stryeski, director of the Siberian Husky Health Foundation (SHHF).

An essential mineral involved in more than 300 enzymes in the body, including those responsible for DNA synthesis and normal cell growth and replenishment, zinc is especially critical for rapidly replaced cells in metabolically active tissues, such as the intestines, immune system and skin. Some of the most common effects of zinc deficiency include reduced immune function and skin disorders, as well as an increased risk for intestinal disorders and allergies.

Signs of Zinc Deficiency

Although the prevalence of zinc deficiency in Siberian Huskies is not known, Stryeski sees it occasionally in her practice. Of the 15 Huskies she has owned over the years, only one was diagnosed with zinc deficiency. Zinc deficiency is ranked as the 12th most common condition in the breed in a recent health survey of owners conducted by SHHF.

The first signs of zinc deficiency in her Siberian Husky were “scaly, itchy patches around the eyebrows, chin and ears and under the muzzle, and the hair fell out easily when it was rubbed,” Stryeski says. “Zinc deficiency looks very similar to mange, skin infections and even ringworm. The big thing is to rule out mange. To accurately diagnose zinc deficiency, a veterinarian should do a skin biopsy.”

Moderate zinc deficiency usually shows up on the skin with frequent irritations or infections, hair loss, reddening, scaling, crusting and lesions. Primary areas affected are the muzzle, legs, elbows, hocks and other pressure points, as well as around the mouth and anus. Crusting may form around the eyes, ears, vulva, scrotum and penis. In some cases, the footpads may be thickened, and the coat may become dull and dry. Secondary skin infections are also common.¹

Prolonged zinc deficiency may result in weight loss, impaired wound healing and inflammation of the eye membrane and cornea. Lymph node conditions are also common, especially in younger dogs. In addition to skin problems, younger dogs may have growth abnormalities as a result of zinc deficiency.¹

Zinc is particularly important in the immune system of animals and humans. Studies in people show that immune function impairment due to zinc deficiency can increase the risk for certain cancers and susceptibility to bacterial infection. Meanwhile, zinc supplementation may reduce the incidence of infection by restoring impaired immune function.²

Determining Zinc Deficiency

Since zinc-responsive dermatosis can mimic other skin disorders, a determination is based on history, age and breed, lesions and their distribution, and examination of skin biopsy specimens.³ Diagnostic testing can include skin scrapes examined microscopically; cytology testing to study cells; fungal cultures to identify bacteria; histologic evaluation through biopsy; and zinc therapy to see if zinc supplementation resolves the problem.³ The ultimate determination comes from an animal’s response to zinc supplementation.³

Two syndromes are associated with zinc-responsive dermatosis. Siberian Huskies typically develop Syndome I, which is caused by an inability of the intestines to properly absorb zinc. Syndrome I affects adult dogs between
1 and 3 years of age despite being fed a complete and balanced dog food. Hypothyroidism, caused by an inactive thyroid gland, may also occur.^{1 3}

Skin lesions due to Syndrome I zinc deficiency often first appear at the onset of adulthood or during stress, which may be due to higher metabolic requirements during these times.¹ Stryeski’s Siberian Husky developed zinc deficiency after delivering a litter of puppies. “She never had zinc deficiency until then,” she says. “Talking with other breeders, we’ve found zinc deficiency can occur during lactation, pregnancy or stress. I’ve seen it in stressed rescue dogs, too.”

Syndrome II occurs in any breed, primarily in rapidly growing puppies fed a marginal or poorly digestible diet with excess phytate, an indigestible substance found in some cereal-based diets that inhibits zinc absorption. Stress or calcium supplementation may incite the problem. Puppies with Syndrome II generally require only short-term zinc supplementation or a switch to a better diet to resolve zinc deficiency.¹

Diet & Zinc Deficiency

Could a Siberian Husky’s diet be blamed for zinc deficiency? Not usually, says Dorothy Laflamme, D.V.M., Ph.D., DACVN, Purina Veterinary Nutritionist. “Most highly digestible, good quality foods provide adequate zinc for dogs, including most Huskies,” she says. “Meats are good natural sources of zinc, but most commercial foods provide zinc as a supplemental salt to assure consistently adequate amounts.”

Although zinc deficiency in Siberian Huskies occurs primarily due to a genetic defect in absorption, Laflamme points out that other dietary factors can contribute. Other nutrients and supplements, especially calcium, can interfere with zinc absorption, she says. “If a calcium supplement is being given or if a diet contains more than 2.0 to 2.5 percent calcium, it can interfere with zinc absorption. Also, diets with low digestibility may have reduced zinc bioavailability.”

Dogs susceptible to zinc deficiency would likely benefit from being fed meat-based diets in which an animal protein source is listed first or second in the ingredient list on the package, Laflamme says. Calcium supplements should not be used.

Supplementation

Some Siberian Huskies require zinc supplementation in addition to being fed a complete and balanced diet. “Most zinc deficiency in Siberian Huskies appears to be related to malabsorption, but the defect can be overcome by providing supplemental amounts of zinc,” Laflamme says. “The amount needed for affected dogs is considerably more than what is needed by other breeds. With adequate, ongoing supplementation, dermatologic signs of zinc deficiency can be completely resolved and eliminated.”

Siberian Huskies with Syndrome I zinc-responsive dermatosis usually need lifelong supplementation with proper veterinary care. A veterinarian will initially prescribe a zinc dosage of 1.0 mg/kg/day of zinc (zinc is provided in salts or other mixtures, so the actual amount of the supplement will be greater than 1.0 mg/kg), and then decrease to between 0.5 to 0.8 mg/ kg/day following resolution of signs, Laflamme says.
“If signs do not resolve within about 30 days, the zinc supplement may be increased by 50 percent,” she says. “It should be divided and provided with meals to reduce risk of gastrointestinal (GI) upset. Injectable zinc may be needed if malabsorption is severe. In most cases after stabilization, dogs can be maintained with oral zinc supplements.”

Once a Siberian Husky shows signs of zinc deficiency, it may take several months to resolve the deficiency once supplementation begins. Stryeski advises owners to work closely with a veterinarian to establish the best dosage for an individual dog. “There’s a fine line with zinc,” she cautions. “Most Siberian Huskies need to get a higher dosage, but you have to be careful to not supplement too much because it can be toxic.”

Laflamme agrees. “Excessive zinc is toxic, so dog owners should not arbitrarily add zinc to their dog’s diet.” Zinc supplements can cause GI upset, with diarrhea, loss of appetite and/or nausea. Zinc toxicity from overdosing can result in depression, vomiting, lethargy and diarrhea. She advises splitting the daily dosage into two or three parts and providing it with food to reduce side effects.

In addition to supplementation, antiseborrheic shampoo can help relieve some of the skin disorder symptoms.⁴

What Breeders Can Do
Since zinc deficiency in Siberian Huskies is a heritable trait, dogs with Syndrome I are carriers of the gene and may transmit the trait. “In time as genetic research progresses, the specific genetic defect for this trait may be identified, which will make it easier to identify and remove carriers from the breeding pool,” Laflamme says. “In the meantime, affected dogs should not be bred. Ideally, their parents and siblings should also be removed from breeding.”
Laflamme advises owners of affected dogs to feed a good quality, complete and balanced, meat-based dog food and to give a zinc supplement prescribed by their veterinarian.

¹ Watson TDG. Diet and Skin Disease in Dogs and Cats. Journal of Nutrition. 1998;128:12, p.2783S-2789S.
² Rink L, Kirchner H. Zinc-Altered Immune Function and Cytokine Production. Journal
of Nutrition. 2000;130,1407S-1411S.
³ Colombini S, Dustan RW. Zinc-responsive dermatosis in northern-breed dogs: 17 cases (1990-1996). JAVMA. 1997;211:4,p.451.
⁴ Nesbitt GH, Ackerman LJ. Canine & Feline Dermatology, Diagnosis and Treatment. Veterinary Learning Systems,Trenton, NJ. 1998;
p.99, pp.276-277.

The Waxing & Waning of Zinc-Responsive Dermatosis

In a study of 17 northern-breed dogs with a diagnosis of zinc-responsive dermatosis, it was found that skin lesions usually went away after zinc supplementation. In fact, in 15 of the 17 dogs the lesions resolved.

Published in the August 1997 issue of the Journal of the American Veterinary Medical Association, the study also found that though nine of 16 dogs experienced recurring lesions, about half of these cases were due to a missed dose or decrease in dosage or frequency of zinc supplementation. Fortunately, the recurrent lesions were less severe than the initial ones.

Lesions appeared anywhere from age 6 months to 10.5 years, with most dogs having a first lesion before age 6. Seven of the 17 dogs experienced lesions before age 2. In 12 dogs, lesions appeared on just one side initially but eventually on both sides as the condition progressed. Itching was present in more than half the dogs and was also the first sign of recurrence, showing up before lesions became visible. The study did not answer whether itching is a primary or secondary component of zinc-responsive dermatosis.

The study findings also indicate that if lesions return as a result of a change in dosage, then it’s important for owners to return to the previous effective dosage. However, even dogs on a long-term, constant dosage of zinc supplementation had lesions recur randomly, suggesting that the disorder waxes and wanes. Recurring lesions didn’t usually respond to increases in dosage or frequency of zinc supplementation, but generally resolved within two weeks if a maintenance dosage was continued.

Source: Colombini S, Dustan RW. Zinc-responsive dermatosis in northern-breed dogs: 17 cases (1990-1996). JAVMA. 1997; 211;4, p.451.

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