In an aging cat, acute onset of skin disease may be the first sign of an underlying systemic disease. The goal of this article
is to help you formulate a diagnostic plan when a geriatric feline patient presents with adult-onset skin disease or changes
to the coat. Based on the clinical presentation and clinical signs, possible differential diagnoses will be discussed as well
as recommendations regarding the first- and second-line diagnostic tests. The diseases and differential diagnoses are grouped
by the presenting complaint or predominant clinical sign. In an older cat with no history of skin disease or in a case in
which a dramatic change to the skin or coat is the presenting complaint, more advanced or aggressive diagnostics are often
warranted on first presentation.
It is imperative to start with a complete and detailed patient history. The history should include where and when the lesions
first started, whether or not the cat is pruritic, a thorough medication history of both long-term and newly administered
medications, any progression or changes in the clinical signs, and any observations about the cat's systemic health (e.g. drinking and urination habits, appetite, weight loss, activity).
It is also important to remember that even though more aggressive diagnostics may be indicated in an older feline patient,
common diseases still occur commonly in older cats. For example, even an older cat can develop lesions secondary to flea hypersensitivity
if there is a break in the administration of flea control products or a change in the cat's environment. Routine monthly flea
preventive is recommended for all cats, regardless of their age.
CORE DIAGNOSTICS
Regardless of the initial presenting complaint, it is important to start the diagnostic investigation with these core dermatologic
tests:
- Cytologic examination of skin and otic samples
- Superficial and deep skin scrapings
- A trichogram
- An otoscopic examination
- A Wood's lamp examination
- Examination of collected hair for adult fleas, flea feces, other ectoparasites, crust, or scale.
A dermatophyte culture is often warranted as a first-line diagnostic test in feline patients, especially if a cat is deemed
to be at risk (e.g. indoor-outdoor lifestyle, new cat added to the household, interaction with other cats). Most of these tests can be performed
during the initial examination. The results of these core diagnostics will directly affect treatment or recommendations for
additional diagnostics.1
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