Black Fungi in Arabian Horses: Scanning Electron Microscopy Study of Cutaneous Equine Mucormycosis Caused by Mucor indicus for the First Time in Eastern Province, Saudi Arabia

Abstract

Four Arabian mares and two Arabian stallions had been admitted to a University Veterinary Medicine Teaching Hospital because of a mass in its right nasal cavity. Horses numbered from 1 to 6. All infections in horses occur in the area of the nostrils. Horse 1 was an Arabian mare of 5-year-old 390kg and had a mass (3.5x3.5 cm in diameter) in its right nasal cavity. Horse 2 was an Arabian mare of 7-year-old 370.0kg and had a mass (4.0x5.5 cm in diameter) in its right nasal cavity. Horse 3 was an Arabian mare of 6.3-year-old 379kg and has a mass (9.0x4.0 cm in diameter) in its right nasal cavity. Horse 4 was an Arabian mare of 5.8-year-old 395.3kg and had a mass (5.0x5.5 cm in diameter) in its right nasal cavity. Horse 5 was an Arabian stallion of 8.2-year-old 421kg and had a mass (4.0x5.5 cm in diameter) in its right nasal cavity. Horse 6 was an Arabian stallion of 7-year-old 471kg and had a mass (4.0x5.5 cm in diameter) in its right nasal cavity. Endoscopic examination of upper respiratory tract revealed a mass that blocked most of the right nasal passage. The mass covered by a bulky pile of ulcerated granulation tissue exuding thick serosanguinous fluid. A specimen of mucor indicus was isolated from a polypes sample and its identity confirmed through LSU rRNA sequence analysis. Microbiological examination showed abundant fungal growth and the strain corresponded to mucor indicus. On histological examination, the dermis and subcutaneous tissue showed the presence of mucor indicus. Mucor indicus confirmed by scanning electron microscopy and light microscopy. Clinical recovery occurred 3 weeks after administration of amphotericin B (40.0 mg/kg body weight/day). The current study concluded that mucor indicus was verified in eastern province of Saudi Arabia for the first time.