Alopecia areata

29 Alopecia areata




INITIAL PRESENTATION


Multifocal, non-inflammatory alopecia and leucotrichia in a Labrador retriever.



INTRODUCTION


Alopecia is a frequent presentation in the dog. The most common causes include hair loss due to pruritus and self-trauma, infectious causes of folliculitis such as pyoderma, demodicosis and dermatophytosis, and hair growth cycle disorders resulting in inactive hair follicles. This case report describes a rare cause of multifocal alopecia in the dog resulting from an autoimmune folliculitis. Distinguishing features in this case include leucotrichia and non-inflammatory alopecia. This dog also had symptoms consistent with mild atopic dermatitis.




CASE PRESENTING SIGNS


A 7-year-old female, spayed, black Labrador retriever was presented with multifocal alopecia and leucotrichia.



CASE HISTORY


Although this is a rare disease and the number of reported cases is limited, most dogs first present with focal or multifocal patches of non-inflammatory alopecia over the face, and around a quarter of cases may also develop leucotrichia. The facial lesions are predominantly symmetrical in distribution. In multicoloured dogs, hair loss may be restricted to hair of one colour.



• The initial signs of disease had first appeared 15 months earlier with the onset of leucotrichia and subsequently non-inflammatory alopecia affecting the face region.

• Over the past few months, the shoulder regions and limbs had become similarly affected.

• In addition to alopecia, there was a history of aural, facial, ventral and pedal pruritus from around 1 year of age.

• There was no history suggestive of systemic involvement.

• There had been intermittent applications of fipronil and selamectin spot-on flea preparations.

• One other animal in the household, a cat, was unaffected and there was no evidence of zoonosis.

• Diet consisted of a combination of tinned food and biscuit mixer, along with scraps and leftovers, dog biscuits and chews.


CLINICAL EXAMINATION


The significant clinical findings in this case were:


• The physical examination was unremarkable.

• There were well-demarcated patches of complete, non-inflammatory alopecia over the face, pinnae, dorsal shoulders, limbs and perivulval area (Figs 29.1 and 29.2).

• Within and surrounding the areas of alopecia there were numerous white hairs.

• All the nails were short and dystrophic (Fig. 29.3).

image

Figure 29.1 Well-demarcated, non-inflammatory alopecia and leucotrichia over the face and head.


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Figure 29.2 Alopecia and leucotrichia over the elbow.


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Figure 29.3 Dystrophic nail.




DIFFERENTIAL DIAGNOSES


There were two clinical presentations to consider: alopecia and pruritus. Historical and clinical evidence indicated that these symptoms were unconnected. This hypothesis was based largely on the history:


• The pruritus had been evident for some years prior to the relatively rapid onset of alopecia.

• There was no historical evidence of increased self-trauma to explain the hair loss.

• The leucotrichia preceded the onset of alopecia.

• The alopecia appeared to be non-inflammatory.

The pattern of gradually spreading, well-demarcated, multifocal alopecia was consistent with a folliculitis. Demodicosis, staphylococcal infections and dermatophytosis are the most common causes of canine folliculitis, but generally result in an obviously inflammatory disease. Autoimmune causes of folliculitis, such as alopecia areata, result in non-inflammatory alopecia and may also involve the nails. Therefore, the differential diagnoses for the alopecia in this case were:


• Alopecia areata

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Sep 3, 2016 | Posted by in SMALL ANIMAL | Comments Off on Alopecia areata

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