Lethal acrodermatitis

What is ... ?: 

This fatal disorder is caused by a defect in zinc metabolism. Stunted growth is usually the first sign, followed by progressive reddening and crusting of the skin around the mouth and eyes, on the ears, and between the toes. Affected pups have a small or absent thymus - a gland that is an important part of the immune system - and commonly develop chronic skin infections, pneumonia, and/or diarrhea.
Affected pups usually die or are euthanized before adulthood, due to untreatable infections and progressive wasting.
Lethal acrodermatitis of bull terriers resembles acrodermatitis enteropathica in people and lethal trait A46 in black pied Danish cattle. However in the disorder in bull terriers, treatment with zinc does not reverse the clinical signs as it does in people and calves.

How is ... inherited?: 

This is an autosomal recessive trait.

What does ... mean to your dog & you?: 

This condition is usually apparent before the pups are weaned. Affected pups are lighter in colour, their growth is stunted, and, usually by 1 to 3 months of age, their feet are splayed with reddening, cracking and crusting of the footpads and skin between the toes. The ears, mouth and eye margins are affected as well. Commonly, these pups develop generalized skin infections, diarrhea, and pneumonia. Although these conditions can be treated symptomatically, there is no treatment for the disorder itself. Affected pups gradually become less and less active, and usually die or are euthanized before the age of 6 or 7 months due to overwhelming infection and progressive wasting.

How is ... diagnosed?: 

Diagnosis is usually made on history and clinical signs in a young bull terrier, especially where siblings are affected as well. Your veterinarian will likely do certain tests to rule out other possible causes of your dog's signs.

How is ... treated?: 

The various infections are treated with appropriate symptomatic therapy. However there is no treatment for the underlying condition. Affected pups do not respond to zinc supplementation.

For the veterinarian: 

If several siblings are affected, a presumptive diagnosis of lethal acrodermatitis can be made. With a single affected dog, rule-outs include pemphigus foliaceus, zinc-responsive dermatosis, demodicosis, dermatophytosis, staphylococcal or Malassezia infection (secondary to congenital immunodeficiency), drug sensitivity. Skin biopsies are characteristic but not diagnostic. Blood profile may show reduced zinc levels, elevated ALT and ALP, and impaired lymphocyte blastogenesis.
On post-mortem the thymus is hypoplastic or absent.

Breeding advice: 

Affected animals generally do not live long enough to breed. Their parents are carriers and should not be bred. Siblings should not be bred either as they have a 50% chance of being carriers of this lethal trait.
FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.

Resources: 

Scott, D.W., Miller, W.H., Griffin, C.E.  1995.  Muller and Kirk's Small Animal Dermatology. p. 797  W.B. Saunders Co., Toronto.


What breeds are affected by ... ?
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