Lupoid onychodystrophy

56 Lupoid onychodystrophy




INITIAL PRESENTATION


Claw abnormalities and pain in a Rhodesian ridgeback.



INTRODUCTION


Lupoid onychitis, also known as symmetrical lupoid onychodystrophy, is considered to be an immune-mediated cutaneous reaction pattern. Often, the initial cause leads to secondary paronychia, which further contribute to the ongoing problem. The condition normally affects several claws on the feet, rather than just a single claw or a single foot and is characterized by progressive shedding of nails over a period of weeks to months with associated pain and paronychia. Histologically, it is characterized by a cell-rich interface dermatitis. Claw abnormalities are described using special terms and those used in this chapter are defined in Table 56.1.


Table 56.1 Various terms used to describe claw abnormalities in this case report
























Term Visible abnormality of the claw
Onychitis Inflammation of the claw
Onychodystrophy Malformation of the claw
Onycholysis Separation of claw from the claw bed
Onychomadesis Sloughing of the claw
Paronychia Inflammation of the claw bed
Onychalgia Claw pain



CASE PRESENTING SIGNS


A neutered male Rhodesian ridgeback, three and a half years of age, was presented with onycholysis, onychomadesis, onychalgia and paronychia.



CASE HISTORY


Most dogs with lupoid onychitis are presented with a history of lameness, feet licking or pain. The duration of onset varies but commonly there is a history of sloughing of one nail and then over a period of weeks nails are sloughed on the majority, if not all, digits on all four feet. Haemorrhage may be evident from affected digits. Lupoid onychitis does not result in systemic illness and affected dogs are in good general health. The condition is not associated with poor nutrition and most dogs are being fed well-balanced commercial pet foods.


The relevant history in this case was:


• A sudden onset of lameness, about 6 months prior to presentation, which responded to meloxicam analgesia.

• There had been further episodes of lameness and foot licking since the initial episode.

• Onychalgia was observed.

• Frequent feet licking and anal pruritus.

• A previous history of otitis and anal pruritus.

• The familial history was not known.

• The dog was fed on a commercial complete dry diet for large breeds.

• It was prone to gastrointestinal disturbances after dietary changes.


CLINICAL EXAMINATION


Onychomadesis and onychalgia are the most common presenting sign. The claws separate from the claw bed with evidence of exudate. Haemorrhage is not always seen, but when the nail plate comes away the claw may bleed profusely. Previously lost claws regrow in a dystrophic manner, with abnormalities such as brittleness, scaling, dryness and distortion.


Clinical findings in this case included:


• Onycholysis, onychomadesis, onychalgia and erythema of the surrounding claw bed (Fig. 56.1).

• Every claw on all four feet was affected (Fig. 56.2).

• Cutaneous abnormalities and systemic signs were absent.

image

Figure 56.1 Separation of the claw plate from the claw bed.


image

Figure 56.2 All the claws of one foot are affected.




DIFFERENTIAL DIAGNOSES


The history and clinical signs were highly suggestive of lupoid onychitis. Some authors suggest that the combination of nail shedding affecting multiple digits with no evidence of systemic illness is pathognomonic for the disease. However, a number of different conditions were considered, including:



• Trauma

• Infections
• Bacterial onychitis

• Fungal onychitis (trichophytosis, malasseziosis, other)

• Immune-mediated diseases
• Lupoid onychitis

• Pemphigus complex

• Bullous pemphigoid

• Epidermolysis bullosa

• Vasculitis

• Adverse drug reaction

• Endocrinopathies
• Hypothyroidism

• Hyperadrenocorticism

• Nutritional causes
• Adverse food reaction

• Deficiency

• Idiopathic onychomadesis and onychodystrophy.


CASE WORK-UP


Based on the history and the clinical signs, trauma was ruled out because of multiple claw involvement. Several diagnostic tests are needed to rule in or out the many conditions that are responsible for claw disease.


The following tests were performed in this case:


• Cytological examination of impression smears from nail folds revealed numerous cocci and smaller numbers of rods.

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Sep 3, 2016 | Posted by in SMALL ANIMAL | Comments Off on Lupoid onychodystrophy

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