Objective: To describe clinical findings and visual outcomes of the fungal plaque form of equine keratomycosis.
Design: Retrospective medical records study. Animals studied: Medical records of horses with the fungal plaque form of keratomycosis that presented to the University of Florida Veterinary Medical Center from 2001 to 2013 were reviewed.
Procedures: Data collected for all horses with corneal fungal plaques at the University of Florida Veterinary Medical Center from 2001 to 2013 included photographs at various points during treatment, and the signalment and clinical description of ocular lesions, medical and surgical treatments, diagnostic test results, and therapeutic outcomes from medical records. Diagnosis of the plaque form of keratomycosis was based on the clinical appearance in addition to cytology and/or histologic results.
Results: Twenty-two horses with keratomycosis with fungal plaques were identified. Corneal scraping found septate hyphae in all 22 eyes. Thirteen eyes (59.1%) had positive fungal culture results from the plaque. Dematiaceous fungi (n=3), Fusarium and Scopulariopsis (n=3), Aspergillus sp (n=4) and unidentified fungi or molds (n=4) were cultured from fungal plaques. Thirty-two percent (n=7) of the eyes cultured had bacterial infections in addition to the fungal infection. Fungi alone were cultured in six eyes (27.3%). Bacteria only were cultured in 6 eyes (27.3%). Culture did not reveal positive bacterial or fungal presence in three (13.7%) plaques. Medical therapy was utilized in all twenty two horses. Ninety-one percent (n=20 horses) of the horses were treated with at least one topical antifungal and at least one topical antibiotic, while one horse was treated with only topical antifungals and one horse was treated with only topical antibiotics. Nine of the horses received one topical antifungal medication and twelve received a combination of two topical antifungal medications with natamycin and either miconazole or voriconazole being the most common combination. Topical antiproteases and mydriatic/cyloplegics, and systemic nonsteroidal anti-inflammatory drugs were used in all horses. Ninety-one percent (n=20 horses) received surgical intervention of some form with 68% (n=15 horses) receiving at least one standing keratectomy and 23% (n=5 horses) receiving a superficial keratectomy under general anesthesia. Mean time to resolution was 6.5±4.1 weeks. Following medical and surgical therapy, 73% (n=16) of the eyes were visual and 27% (n=6 horses) were enucleated. The mean time to resolution of horses in which vision was preserved was 7.5±3.6 weeks.
Conclusions: The visual outcome of therapy of 22 horses with the dark fungal plaque form of keratomycosis was positive in 73%. Successful treatment of the fungal plaque form of keratomycosis was aided by plaque removal, usually hastened by performing one or more keratectomies, and concurrent successful management of corneal ulceration and accompanying uveitis.
Keywords: Cornea, fungus, horse, keratomycosis, plaque