Vet360 Vol 03 Issue 03 June 2016 | Page 23

DERMATOLOGY the affected claw as possible. Topical antibiotics or in more severe cases, oral antibiotics should be given until the lesion is healed and enough until the normal claw is covering the previously affected area. Fungal claw diseases Fungal infections are rare and organisms which have been reported in claw and often nail bed diseases are: Malassezia, dermatophytes (especially Trichophyton), followed by blastomycosis, cryptococcosis, sporotrichosis. Dogs with Malassezia infections show brownred discoloration of the claw with brown-colored waxy exudate on the proximal aspects of the claws. This condition is very often seen in dogs with allergies. Diagnostic tests, which will help to identify the organisms, are: cytology, Wood’s lamp, fungal culture, and biopsy. Most of these fungal infections (except Malassezia) require aggressive systemic anti-fungal therapy. Itraconazole and terbinafine have been shown to accumulate in keratin, horn, and hairs. Parasitic diseases Parasites such as Demodex do not affect the claws, directly but if not treated appropriately, will result in secondary changes due to persistent inflammation and secondary infections. Demodex mites are often difficult to find on skin scrapes from pedal skin, due to their deep follicular localisation in those areas. Sometimes skin biopsies are necessary to confirm a demodicosis of the feet (due to thickening of the epidermis...Ed) Other parasites which have been reported to cause onychogryphosis are Leishmania and hookworms, which may require specific laboratory tests to confirm the disease. Symmetrical lupoid onychodystrophy Based on the clinical presentation, inflammatory pattern and response to therapy, symmetric lupoid onychodystrophy should be considered an immunemediated disease or vasculopathy. This disease can occur in different breeds (personally seen in Greyhound, Schnauzer, Labrador Retriever), but German Shepherds are considered predisposed to this disease. The problem usually starts with one claw, but within a couple of weeks other claws become affected. The animals appear otherwise healthy, but once the claws start to slough off they become painful, Show lameness, and secondary infections. The claw horn continues to grow, but the horn quality is poor. The claw appears short, discoloured, deformed, soft and crumbly and tends not to attach well to the underlying nail bed. (Figure 1) Histopathology (hydropic and lichenoid interface dermatitis) is usually required to confirm the diagnosis. Because the histological lesions are located very deep at the claw base, amputation of the 3rd phalanx may be necessary to be able to diagnose the disease. Treatment of this disease requires immunosuppressive therapy with steroids and high doses of omega-3 and Figure 1: Symmetrical Lupoid Onychodystrophy demostrating short, deformed, crumbling, soft nails. omega-6 fatty acids (e.g. Derm Caps or Omegaderm) with Vit E, or tetracycline with niacinamide. Improvement and claw regrowth should be noticed within 3-4 months. Auto-immune diseases Very rarely auto-immune diseases such as pemphigus vulgaris, foliaceus or erythematosus may affect claws besides other skin areas. A biopsy of the nail bed is usually required to diagnose the disease. As with auto-immune diseases in general, immune-suppressive therapy is required to manage this disease. Neoplasia Among the most common neoplasia involving the claws, squamous cell carcinoma, melanoma and mast cell tumors should be considered. Other differentials such as inclusion cysts, keratocanthoma, and inverted papilloma should be ruled out. In cats, nail bed tumors are rare, but metastasis of primary lung carcinoma, hemangiosarcoma and squamous cell carcinoma have been reported. Tumors usually form solitary lesions. Melanoma and mast cell tumors may be aggressive and tend to metastase. All neoplasia should be diagnosed by histopathology and aggressive excision or amputation of the affected digit is usually curative. Miscellaneous rare claw diseases Idiopathic onychodystrophy affect multiple claws in older dogs. This condition appears to be predisposed in Siberian Husky, Dachshund, Rhodesian Ridgeback, Rottweiler and Cocker Spaniel. Biotic and gelatin may help to improve the horn quality of the claws. Idiopathic onychomadesis has been reported in German Shepherd, Whippet, and English Springer Spaniel. Secondary claw infections are not uncommon. Anecdotal reports suggest the use of pentoxifylline. Anecdotal reports of diseases such as epidermolysis bullosa, dermatomyositis, drug eruption, ergotism, thallotoxicosis, linear epidermal nevi, nutritional deficiencies, disseminated intravascular coagulation, and necrolytic migratory erythema do exist. References available on www.vet360.vetlink.co.za Shaping the future of animal health Issue 03 | JUNE 2016 | 23 JUNE 2016 Vet360 working.indd 23 2016/05/24 12:04 AM