Small Animal Dermatology Q&A 09

This question was provided by Manson Publishing as part of the OVAL Project. See more small animal dermatological questions

A cat was presented for lameness. Note the swollen skin around the base of the nails.

Question	Answer		Article
What is this condition called, and what are the most common causes of this condition in the cat?	Paronychia. The most common causes of paronychia in the cat are trauma, dermatophytosis, Malassezia dermatitis, demodicosis, Notoedres mites, and PF.		Link to Article
What diagnostic tests are indicated?	A Wood’s lamp examination is optional, but a dermatophyte culture should be prepared. Exudate from the nail base should be collected, smeared on a glass microscope slide, heat fixed, and stained. Malassezia dermatitis is an under-recognized skin disease in cats, and the most common presentation is an accumulation of black debris under the nail. Bacterial culture and sensitivity should also be done, along with a skin scraping using mineral oil to look for mites. A skin biopsy may be needed for a definitive diagnosis.		Link to Article
A smear of the exudate from the nail bed is shown. How could these findings be described, and what is the most likely diagnosis?	There is neutrophilic inflammatory exudate with large basophilic epithelial cells. These cells are compatible with what would be described as ‘acantholytic cells’. These are epidermal cells from the stratum spinosum that have been shed into the pustular exudate. These cells are often seen in patients with PF and in patients with severe deep pyoderma. In PF, the cells are usually very numerous and often present in rafts of 6–8 cells. In patients with deep pyoderma, the number of cells adhered together are fewer, often just two or three. This was a case of paronychia due to a Microsporum canis infection.		Link to Article