CHAPTER 40 PODODERMATITIS AND CLAW DISORDERS 589
Onychogryphosis: abnormal curvature of the claw.
Onycholysis: separation of claw at proximal attachment.
ETIOLOGY/PATHOPHYSIOLOGY
Claw, claw/ungual folds, footpads: subject to trauma, infection, vascular insufficiency,
immune-mediated disease, parasites, neoplasia, defects in keratinization, and congen-
ital abnormalities.A particular claw deformity may be caused by a variety of diseases; claw disease is
most often associated with other dermatoses – rarely the only epithelial structure
affected.A single disease can present with various claw lesions.
Pododermatitis is a multifaceted disease complex.
One foot affected: top differentials include foreign body, neoplasia, trauma, fungal
infection, bacterial infection.
Multiple feet affected: allergy, endocrine, secondary infections, demodicosis, immune-
mediated disorders, epidermolysis bullosa, symmetric lupoid onychodystrophy,
plasma cell pododermatitis, superficial necrolytic dermatitis, nutritional deficiencies,
psychogenic dermatoses, idiopathic.SIGNALMENT/HISTORY
Claw and claw fold diseases: 1.3% dogs and 2.2% cats.
Collie and Shetland sheepdog: dermatomyositis (Figure 40.1).
Dachshund: onychorrhexis (Figures 40.2, 40.3).
German shepherd dog, rottweiler, giant schnauzer and doberman pinscher: symmet-
ric lupoid onychodystrophy (Figures 40.4–40.6).
Siberian husky, dachshund, Rhodesian ridgeback, rottweiler, cocker spaniel: idio-
pathic onychodystrophy; keratinization defects.
Bull terrier: acrodermatitis, footpad hyperkeratosis.
Irish terrier, French mastiff, Kerry blue terrier, Labrador retriever, golden retriever:
familial footpad hyperkeratosis.
English bulldog, Great Dane, dachshund: idiopathic sterile granuloma (Figures 40.7,
40.8).
German shepherd dog, whippet, English springer spaniel: idiopathic onychomadesis.
Devon rex cats:Malasseziaparonychia.
German shepherd dog: nodular dermatofibroma.
Gordon setter: genetic predisposition for symmetric lupoid onychitis.
Risk Factors
Claw and claw fold are carrier sites forMalassezia pachydermatisandBartonella
henselae.