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Paronychia in the nail bed of a Maltese

Paronychia is a rare inflammatory skin disease of the nailbeds, usually associated with Malassezia spp yeast or Microsporum spp fungal infections.

Although paronychia appears to be rare compared to this disease in cats, there is an underlying infection attributable to Malasezzia pachydermatitis and gram negative bacteria.

Various bacteria have been isolated from within lesions, including Staphylococcus spp, Streptococcus spp, Pseudomonas spp and Proteus spp. Multiple bacterial paronychia should lead to suspicion of an underlying dermatosis or systemic illness (e.g. the Bull Terrier and paronychia with lethal acrodermatitis)[1].

In many cases, there is marked cystic dilation of hair follicles and sebaceous glands with follicular hypoplasia, infundibular hyperkeratosis and variable associated inflammation.

Responses are usually good to weekly bathing with Malaseb or other proprietary shampoos which are antibacterial and antifungal.

The use of antifungal oral medication is warranted in cases that are non-responsive to topical shampoos.


  1. McEwan NA et al (2000) Diagnostic features, confirmation and disease progression in 28 cases of lethal acrodermatitis of bull terriers. J Small Anim Pract 41(11):501-507