Experimental pythiosis in rabbits.

Area of Science:

• Veterinary Mycology
• Pathology
• Immunology

Background:

• Pythium species, known plant pathogens, can cause infections in animals.
• Subcutaneous lesions in horses can harbor Pythium species.
• The pathogenicity of Pythium zoospores in mammals is not well understood.

Purpose of the Study:

• To investigate the pathogenicity of a Pythium sp. in rabbits via different inoculation routes.
• To determine the effect of cortisone administration on Pythium sp. infection susceptibility and pathology.
• To observe the hematological response to Pythium sp. infection.

Main Methods:

• Rabbits were inoculated subcutaneously, intraperitoneally, or intravenously with Pythium sp. zoospores.
• Some rabbits received concurrent cortisone injections.
• Lesions, clinical signs, and hematological parameters were monitored.

Main Results:

• Subcutaneous inoculation caused granulomatous eosinophilic abscesses.
• Intraperitoneal inoculation led to necrotizing hepatitis.
• Intravenous inoculation resulted in embolic mycotic nephritis.
• Immune-competent rabbits showed leukocytosis; cortisone-treated rabbits did not.
• Cortisone did not increase susceptibility to fungal infection but increased susceptibility to bacterial infection in control animals.

Conclusions:

• Pythium sp. zoospores are pathogenic in rabbits, causing distinct lesions based on inoculation route.
• Cortisone administration did not enhance susceptibility to this Pythium sp. fungal infection.
• Further research is needed to understand the immune response to Pythium infections.