Opportunistic Fungal Infections in Small Animals

Abstract

Opportunistic fungal infections have long been recognized as rare causes of disease in immunocompetent dogs and cats. Recently, the escalating use of multiagent immunosuppression protocols (especially those that include cyclosporine) has resulted in an increased number of patients with opportunistic fungal infection encountered by small animal practitioners and has altered the typical case phenotype. Based on histologic and cytologic features such as pigmentation, hyphal diameter, and distribution in tissue, these opportunistic mycoses can be placed into categories such as phaeohyphomycosis, hyalohyphomycosis, and eumycotic mycetoma. This review aims to summarize the clinical presentations, methods for diagnosis, treatment recommendations, and prognosis for both immunocompetent and immunosuppressed patients with opportunistic fungal infections. An example case description is included to illustrate the most common current clinical presentation.

First case report of cutaneous sporotrichosis (Sporothrix species) in a cat in the UK

“…It is possible that the infection could have resolved with management of the diabetes mellitus alone, but treatment of opportunist fungal infections is recommended. 27 The prolonged course of itraconazole was well tolerated, although this can be associated with gastrointestinal disease and hepatopathy, and thus liver enzymes should be regularly monitored. 3,26…”

Severe chronic idiopathic suppurative lymphoplasmacytic rhinitis in a dog

“…24 Over the past years, the frequency of opportunistic fungal infections has increased substantially not only in humans but also in dogs with the use of multi-agent immunosuppressive therapy to treat immune-mediated diseases. 26,27 Although the prevalence of documented serious fungal infections appears to be relatively low in dogs treated with glucocorticoids and cyclosporin, the poor outcome in the majority of the dogs of a case series 27 highlights the need for caution in the use of immunosuppressive therapy until a fungal infection has been ruled out and frequent clinical monitoring once treatment is started.…”

Successful Treatment of Cutaneous Curvularia geniculata, Nocardia niigatensis, and Viral Papillomatosis in a Dog During the Therapeutic Management of Immune-Mediated Hemolytic Anemia

“…), Alternaria spp., Bipolaris spp., Cladosporium spp., and Paraconiothyrium spp. (2, 3, 6). In this report, cutaneous OIFI affecting right forelimb was developed during 6-week multi-agent immunosuppressive protocol for IMHA and Curvularia geniculata was identified as a causative agent using next-generation sequencing from the fungal culture.…”

“…In this report, cutaneous OIFI affecting right forelimb was developed during 6-week multi-agent immunosuppressive protocol for IMHA and Curvularia geniculata was identified as a causative agent using next-generation sequencing from the fungal culture. Treatment of dogs that develop cutaneous OIFI, consists of discontinuation of immunosuppressive medications, administration of antifungal medications and surgical excision if lesions are solitary or on a distal extremity (3, 6). Discontinuing ciclosporin administration and reducing the dosage of prednisolone resulted in spontaneous cutaneous phaeohyphomycosis resolution in a single dog while IMHA was controlled in remission (9).…”

“…Reports of opportunistic cutaneous infections in dogs associated with immunosuppression include Nocardia species (1), saprophytic fungi (phaeohyphomycosis and hyalohyphomycosis) (2, 3) and viral-induced papillomas (4, 5). Discontinuation of immunosuppressive medications is recommended with the development of opportunistic infections, which may cause a relapse or worsening of the immune-mediated disease (3, 6).…”