A diagnostic approach to skin disease in geriatric cats - Veterinary Medicine
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A diagnostic approach to skin disease in geriatric cats
When an older cat develops a skin problem, the presenting complaint will point you to a group of possible diagnoses. From there, a thorough patient history and core diagnostic tests can help you identify the underlying problem.


VETERINARY MEDICINE


Excessive scaling

Scale refers to flakes of keratin that break off from the cornified layer of the epidermis. Scaling as a new clinical sign should prompt a thorough investigation using core diagnostic tests.2 Dermatophytosis should also be ruled in or ruled out based on the results of a trichogram, Wood's lamp examination, and fungal culture. It is important to ask the owner whether any animals have been added to the household as well as about the use of flea control products. Deep and superficial skin scrapings are useful in determining whether Cheyletiella or Notoedres species infections are causes of scale. A fecal examination can also be helpful if certain contagious mites (i.e. Demodex gatoi) are suspected.3


2. Large scales on the cranial dorsum of a cat with paraneoplastic exfoliative dermatitis secondary to thymoma. A skin biopsy site can be seen on the cat's neck.
If core diagnostics do not reveal the underlying cause, other differential diagnoses include immune-mediated skin diseases, such as pemphigus foliaceus or degenerative mucinous lymphocytic mural folliculitis. Immune-mediated diseases are diagnosed based on the results of a skin biopsy, which would be indicated in an older cat once both bacterial and fungal infections have been ruled out or treated.4

Primary skin neoplasia (epitheliotrophic T cell lymphoma) or paraneoplastic exfoliative dermatitis can also present as excessive scaling with varying levels of pruritus (Figure 2). Scales are often large and broad, sometimes exfoliating in sheets. Other possibilities include drug eruption, erythema multiforme, and sebaceous adenitis. Skin biopsy can be diagnostic; however, because paraneoplastic exfoliative dermatitis is associated with thymoma, full blood work and thoracic radiographs are recommended if the skin biopsy comes back as consistent with paraneoplastic dermatitis or if biopsy results are nonspecific. Surgical removal of the thymoma can be curative in these cases.5,6

The treatment of and prognosis for diseases associated with scaling are quite variable, so determining a definitive diagnosis is important to be able to have an informative conversation with the owner.


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Source: VETERINARY MEDICINE,
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