Pruritic cats can have any of the following three clinical presentations:
For all presentations, the differential diagnoses and diagnostic approach are the same.
- Flea allergy is the most common cause of pruritis in cats
- Food allergy and atopy also occur
- Possible pruritic minutes include Demodex gatoi, Cheyletiella, and Notoedres
- Paraneoplastic pruritus can occur with internal neoplasia
- Dermatophyte infections, autoimmune diseases, and cutaneous lymphoma are not usually pruritic but the can cause alopecia and crust or scale
Diagnostic and Therapeutic Approach
Tape and/or impression cytology and skin scrapings should be performed to look for secondary bacterial or yeast infections and mites.
A dermatophyte culture should be performed since this disease is zoonotic.
If cytology and scrapes are negative, then a strict flea control trial is needed. To diagnose flea allergy, we recommend giving the Novartis product Capstar orally every other day for a month. If there is no improvement with this therapy, then flea allergy is unlikely. To rule out Cheyletiella and Notoedres in conjunction with the flea trial, consider applying the Pfizer product Revolution every two week for three treatments.
If the strict flea trial fails to improve pruritis, then consider treatment trials for either food allergy or Demodex gatoi. Select the trial based on which approach is easiest for the specific cat and owner. If the first trial fails, then attempt a trial for the next disease.
If the patient is an older cat, consider skin biopsies early on to rule out neoplasia.