Special Veterinary Pathology

ZYGOMYCOSIS 

Synonym – Phycomycosis

• The term Zygomycosis includes those disorders which are caused by fungi classified in the class Zygomycetes

Aetiology

• Zygomycetes grow on decaying vegetation and are pathogenic
• Intercurrent disease, long term administration of antibiotics, immunosuppression leads to serious disease

Gross lesions

• Involves the skin or mucous membranes of the oral and nasal cavities
• Lungs, placenta, mammary glands, rumen, stomach, kidneys and brain are the common sites
• Mucormycosin – Cattle – Placentitis, abortion, infection of the rumen and abomasum
• Horses – placentitis and abortion
• Dogs – Digestive tract lesions

Microscopic lesions

• Diffuse and not in the form of granulomas
• Highly invasive, spreads through blood vessels
• Leads to thrombosis, infarction, dissemination of infection
• Lesions characterized by macrophages, multinucleated giant cells, necrosis, neutrophils resembling pyogranulomatous inflammation with necrosis and pus
• Zygomycetes fungi appear as pleomorphic, branching hyphae staining basophilic with H&E

Diagnosis

• Demonstration of characteristic organisms in granulomatous lesions