Morphea-like lesion following topical endectocide application in a cat
ABSTRACT Scleroderma is a rare chronic disease of connective tissues that may affect the skin in humans. Although still unclear, its aetiology may be related to drug reactions. To date, scleroderma has been reported in only a few dogs and one cat.
Localized (morphea-like) scleroderma was diagnosed in a 3-year-old intact male Persian cat that developed a nonpruritic, well-demarcated alopecic plaque a few days after topical application of a 'spot-on' solution containing praziquantel and emodepside. The lesion occurred at the site of application at the dorsal cervical region, and was characterized histologically by fibrosing dermatitis. There was no response to systemic treatment with pentoxifylline. Following topical therapy with minoxidil 5% for 30 days, hair regrowth occurred, and the lesion had completely disappeared after 60 days.
The relationship between the alopecic plaque and the topical application of the spot-on solution cannot be proved; however, according to the Naranjo scale, which estimates the probability of adverse drug reactions, this case could be classified as a 'possible' reaction to one of the components of the product. Sclerodermoid reactions have not been described as a cutaneous drug eruption in veterinary medicine, so this case may possibly represent the first such idiosyncratic reaction to one of the applied substances. Furthermore, to the best of the authors' knowledge, this is the second report of a morphea-like lesion in a cat.
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ABSTRACT: A formulation containing 39.6% spinetoram resulted in a higher than anticipated number of reports of alopecia at the site of application in the first months following commercial product launch. To determine the cause of the alopecia using histopathology, including assessment for inflammation, follicular findings of physical trauma (plucking/pulling behaviour) and changes in follicular cycling. Twenty-four flea-free, male and female adult domestic short hair cats within a private research colony. Cats were treated with a single application of 39.6% spinetoram on day 0; personnel were not blinded. Observations of the skin and hair coat began immediately and were repeated at 30 min and 1, 2, 3, 4, 6, 8 and 12 h post-application and then on subsequent days at the same time as initial dosing and at 2, 4, 6, 8 and 12 h after that time, until day 5. If hair thinning or loss was observed, a skin biopsy sample was collected. Two cats not exhibiting abnormalities were biopsied on day 6. Thirty-eight per cent of cats (nine of 24) developed hair thinning and alopecia of sufficient severity within 78 h post-application of the product to warrant skin biopsy. Abnormalities in the skin were limited to the application site and were consistent with physical trauma (pulling or plucking) to the hair. Microscopic changes in the hair follicles of affected cats were consistent with self-induced trauma or barbering behaviour. All changes were reversible and paralleled findings associated with well-established, topical flea control products.Veterinary Dermatology 09/2013; 24(6). DOI:10.1111/vde.12075 · 1.99 Impact Factor