434 DISEASES/DISORDERS
parakeratosis of Labrador retrievers (begins at less than 1 year of age; often more
severe) (Figure 29.14).Footpad hyperkeratosis: severe keratin proliferations of all pads; fissuring results in
secondary infection; Irish terrier, dogue de Bordeaux, Kerry blue terrier, Labrador
retriever, golden retriever less than 6 months of age (Figure 29.15).Zinc-responsive dermatosis: supplement responsive; alopecia, dry scaling, crusting,
and erythema around the eyes, ears, feet, lips, and other external orifices; two syn-
dromes: syndrome 1 young adult dogs, primarily Siberian husky and Alaskan mala-
mute; syndrome 2 rapidly growing, large-breed puppies (often fed an unbalanced
diet) (Figures 29.16, 29.17).Color dilution alopecia: abnormal melanization of the hair shaft and structural hair
growth; large melanosomes result in structural damage to the hair shaft and bulb;
keratinization defect theorized as causative for several syndromes; blue and fawn
doberman pinscher, Irish setter, dachshund, chow chow, Yorkshire terrier, poodle,
Great Dane, whippet, saluki, Italian greyhound; failure to regrow blue or fawn hair
with normal “point” hair growth, excessive scaliness, comedone formation, secondary
pyoderma (Figures 29.18, 29.19).Sebaceous adenitis: autosomal recessive inheritance in the standard poodle and
Akita; begins in the young adult dog; increased incidence in male dogs; caused by
cell-mediated inflammation targeting the sebaceous gland and duct; may also be a
response to abnormal lipid storage or keratinization; additional predisposed breeds
include the samoyed, havanese, German shepherd, and vizsla; also occurs in their
cross-breeds as well as in other breeds.Standard poodle, samoyed, and havanese: patchy or diffuse hair loss and excessive
scaling; tightly adherent follicular casts (“keratin collaring”); commonly begins on
the muzzle, dorsal head, and neck; most dogs are healthy and asymptomatic (Fig-
ures 29.20, 29.21).Akita: initial lesions similar to those of poodles but more generalized; significant
alopecia; severe and deep bacterial pyoderma common as well as systemic signs of
illness (Figures 29.22, 29.23).Vizsla: distinctly different and granulomatous; firm, coalescing plaques with fine
adherent scales; lesions primarily on the trunk; also on the pinnae and face (Fig-
ure 29.24).Schnauzer comedo syndrome: miniature schnauzer; small comedones develop on the
dorsal spine; lesions may coalesce and appear as large patches of hyperpigmentation;
secondary bacterial folliculitis leads to alopecia and crusting (Figure 29.25).Psoriasiform-lichenoid dermatosis: predominantly in springer spaniel; also reported
in English pointer, Irish setter, poodle; coalescing, crusted, erythematous papules
form plaques with adherent debris; predilection for the pinnae and ventrum; may
represent a staphylococcal hypersensitivity; similar pattern reported as an adverse
reaction to cyclosporine (Figure 29.26).Acrodermatitis of bull terrier: rare; exclusively in white dogs; usually fatal; associ-
ated with decreased serum copper and zinc concentrations; lesions similar to but
more severe than other metabolic and nutritional dermatoses (e.g., zinc-responsive
dermatosis and superficial necrolytic dermatitis); thick crusts, papules, pustules,