History
A 3-year-old spayed female mixed-breed dog with a history of brittle nails on all 4 limbs was evaluated by the referring veterinarian. The owners treated this dog orally with cefpodoxime proxetil (dosage and duration unknown), but no improvements in clinical signs were reported.
Clinical and Gross Findings
Abnormal physical examination findings were limited to the integumentary system. The claws of all paws were brittle and misshapen (Figure 1). Several nails were broken. Amputation of a single claw was performed and submitted to the University of Illinois Veterinary Diagnostic Laboratory for diagnostic examination.
Photograph of a claw of a 3-year-old spayed female mixed-breed dog with a history of brittle nails on all 4 limbs. Notice the disfigurement of the claw.
Citation: Journal of the American Veterinary Medical Association 246, 2; 10.2460/javma.246.2.197
Photograph of a claw of a 3-year-old spayed female mixed-breed dog with a history of brittle nails on all 4 limbs. Notice the disfigurement of the claw.
Citation: Journal of the American Veterinary Medical Association 246, 2; 10.2460/javma.246.2.197
Photograph of a claw of a 3-year-old spayed female mixed-breed dog with a history of brittle nails on all 4 limbs. Notice the disfigurement of the claw.
Citation: Journal of the American Veterinary Medical Association 246, 2; 10.2460/javma.246.2.197
Formulate differential diagnoses from the history, clinical findings, and Figure 1—then turn the page →
Histopathologic Findings
The claw was immersion fixed in neutral-buffered 10% formalin. Tissues were routinely processed for histologic evaluation and stained with H&E stain. On microscopic examination, the interface of the claw bed epithelium and dermis was multifocally obscured by moderate numbers of lymphocytes and macrophages mixed with fewer plasma cells (Figure 2). There was vacuolation of basal keratinocytes of the claw bed epithelium and rare basal keratinocyte apoptosis. Moderate pigmentary incontinence was present.
Photomicrographs of sections of the nailbed of an amputated claw from the fourth digit of the left hind paw of the dog in Figure 1. A—Inflammatory infiltrate is present at the dermoepidermal junction. B—Notice the interface dermatitis (arrow) with loss of a distinct dermal-epidermal junction with pigmentary incontinence. H&E stain; bar = 200 μm.
Citation: Journal of the American Veterinary Medical Association 246, 2; 10.2460/javma.246.2.197
Photomicrographs of sections of the nailbed of an amputated claw from the fourth digit of the left hind paw of the dog in Figure 1. A—Inflammatory infiltrate is present at the dermoepidermal junction. B—Notice the interface dermatitis (arrow) with loss of a distinct dermal-epidermal junction with pigmentary incontinence. H&E stain; bar = 200 μm.
Citation: Journal of the American Veterinary Medical Association 246, 2; 10.2460/javma.246.2.197
Photomicrographs of sections of the nailbed of an amputated claw from the fourth digit of the left hind paw of the dog in Figure 1. A—Inflammatory infiltrate is present at the dermoepidermal junction. B—Notice the interface dermatitis (arrow) with loss of a distinct dermal-epidermal junction with pigmentary incontinence. H&E stain; bar = 200 μm.
Citation: Journal of the American Veterinary Medical Association 246, 2; 10.2460/javma.246.2.197
Morphologic Diagnosis and Case Summary
Morphologic diagnosis: locally extensive, moderate lymphohistiocytic and plasmacytic interface dermatitis with basal cell degeneration, basal cell apoptosis, and pigmentary incontinence (consistent with lupoid onychitis [also known as symmetric lupoid onychodystrophy]) of the claw bed epithelium.
Case summary: symmetric lupoid onychodystrophy in a dog.
Comments
Diseases that can affect the claws of dogs include bacterial paronychia, onychomycosis, symmetric lupoid onychodystrophy, nailbed keratoacanthoma, nailbed epithelial inclusion cyst, and claw bed squamous cell carcinoma.1–3 Other diseases may involve the claw bed. In addition, diseases not limited to the claw bed (eg, vasculitis, systemic lupus erythematosus, hepatocutaneous syndrome, pemphigus vulgaris, and bullous pemphigoid) are reported to affect the claw beds; however, other cutaneous lesions are expected to develop in animals with those diseases.1,3
Symmetric lupoid onychodystrophy is an uncommon disease of the claw bed. Large-breed dogs such as German Shepherd Dogs and Rottweilers may be at an increased risk for development of this disease.4 Young to middle-aged adult dogs are affected by this syndrome.1
The pathogenesis of lupoid onychitis has been incompletely elucidated. In 1 study,5 sequence-based genotyping of dog leukocyte antigen class II in 196 Gordon Setters (98 with symmetric lupoid onychodystrophy), 10 Bearded Collies, and 110 Giant Schnauzers revealed both a risk haplotype (DRB1*01801/DQA1*00101/DQB1*00802) and a protective haplotype (DRB1*01301/DQA1*00301/DQB1*00501) supporting symmetric lupoid onychodystrophy as an immune-mediated disease. Allergic, infectious, and immune-mediated diseases have been associated with symmetric lupoid onychodystrophy.4–6 Some authors believe that the histopathologic changes associated with symmetric lupoid onychodystrophy are a reaction pattern rather than a separate disease entity.3,6
In dogs with symmetric lupoid onychodystrophy, there is separation of the claw from the claw bed of several digits. Subsequent to the separation, sloughing of a claw can occur. Within 2 to 3 months, all claws may become affected.1,5 Claws will regrow, although appearing grossly misshapen, and will be characterized by dryness and brittleness and a likelihood of crumbling.7 Hemorrhage at sites of sloughing is an inconsistent feature. Lameness and signs of pain have been reported for dogs with this syndrome.8
Definitive diagnosis of symmetric lupoid onychodystrophy is obtained on the basis of histopathologic findings in the claw bed. Interface dermatitis comprised predominately of lymphocytes (both B cells and T cells) and lesser numbers of macrophages is the hallmark feature.1,6,7 Apoptosis and vacuolation of basal cells are commonly observed, and there is pigmentary incontinence. Because there is damage of the dermal-epidermal junction, biopsy specimens may have artifactual dermal-epidermal separation that occurs during processing.1
Optimal biopsy specimens are obtained by means of amputation of the distal aspect of a phalanx, which is best performed on an affected non–weight bearing digit or hallux (dewclaw). A sloughed claw does not usually contain the claw bed, and submission of such a sample is rarely of benefit in cases of symmetric lupoid onychodystrophy.8,9 However, a sloughed claw may be valuable for diagnosis of a fungal or bacterial infection via culture. A newer technique has been described9 in which a biopsy punch is used to obtain a sample that includes some of the distal phalanx. This technique collects only a small portion of the lateral claw matrix, and localized abnormalities may be missed, necessitating digit amputation. Inexperience with this newer technique may provide a sample of poor diagnostic quality, thereby resulting in misdiagnosis.9
With most treatments, the interval until an observable response is evident in affected dogs is at least 3 to 4 months, and as much as 1 year. If treatments are discontinued, the disease will most likely recur to some extent.4,10,11 Tetracycline or doxycycline with niacinamide has been reported to have good to excellent response rates among affected dogs.12 Supplemental omega-3 and omega-6 fatty acids are usually administered in combination with other treatments. For fatty acid supplementation as a sole treatment, response rates are reported from good to excellent historically; however, more recent reports4,11,12 have noted comparatively lower success rates and describe failure to respond or poor response. Pentoxifylline has been used typically as adjunctive therapy, and response rates are difficult to determine.12 When no response to these treatments has been evident, more aggressive treatment with drugs (eg, glucocorticoids [systemic and topical administration] or azathioprine) or onychectomy has been performed with variable success.12–14 Gelatin and biotin administered orally have also been used to help strengthen the claw and prevent fractures.10,15 Claw trimming was used successfully in 1 dog to decrease the continuous traumatic insult from contact surfaces.16 Although symmetric lupoid onychodystrophy in dogs is uncommonly reported, it is important for veterinary practitioners to be aware of this disease because the clinical signs are unique and it should be on the differential diagnosis list in cases of disfigured and brittle nails.
References
1. Gross TL, Ihrke PJ, Walder EJ, et al. Mural diseases of the hair follicle. In: Gross TL, Ihrke PJ, Walder EJ, et al, eds. Skin diseases of the dog and cat. Clinical and histopathologic diagnosis. 2nd ed. Ames, Iowa: Blackwell Science, 2005; 49–70.
2. Mueller RS, Friend S, Shipstone MA, et al. Diagnosis of canine claw disease—a prospective study of 24 dogs. Vet Dermatol 2000; 11: 133–141.
3. Neuber A. Nail diseases in dogs. UK Vet 2009; 14: 1–6.
4. Scott DW, Rousselle S, Miller WH. Symmetrical lupoid onychodystrophy in dogs: a retrospective analysis of 18 cases (1989–1993). J Am Anim Hosp Assoc 1995; 31: 194–201.
5. Wilbe M, Ziener ML, Aronsson A, et al. DLA class II alleles are associated with risk for canine symmetrical lupoid onychodystrophy (SLO). PLoS ONE [serial online] 2010;5: e12332. Available at: www.plosone.org;article;info%3Adoi%2F10.1371%2Fjournal.pone.0012332. Accessed Mar 1, 2013.
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11. Bergvall K. Treatment of symmetrical omychomadesis and onychodystrophy in five dogs with omega-3 and omega-6 fatty acids. Vet Dermatol 1998; 9: 263–268.
12. Mueller RS, Rosychuck RAW, Jonas LD. A retrospective study regarding the treatment of lupoid onychodystrophy in 30 dogs and literature review. J Am Anim Hosp Assoc 2003; 39: 139–150.
13. Paterson S. Successful protocol for therapy of lupoid onychodystrophy: 12 dogs. Vet Dermatol 2004;15 (suppl 1): 58.
14. Boord MJ, Griffin CE, Rosenkrantz WS. Onychectomy as a therapy for symmetric claw and claw fold disease in the dog. J Am Anim Hosp Assoc 1997; 33: 131–138.
15. Foil C, Conroy J. Dermatoses of claws, nails, and hoof. In: von Tscharner C, Halliwell REW, eds. Advances in veterinary dermatology. Vol 1. Philadelphia: Bailliere Tindall, 1990; 420.
16. Verde MT, Basurco A. Symmetrical lupoid onychodystrophy in a crossbred Pointer dog: long-term observations. Vet Rec 2000; 146: 376–378.
