Hexamitiasis in a laboratory mouse colony.

Area of Science:

• Veterinary Pathology
• Parasitology
• Murine Models

Background:

• An acute, fatal disease outbreak impacted a mouse colony, leading to 50% mortality in weanling mice.
• Clinical signs included depression, rough hair coat, and abdominal distention, indicative of gastrointestinal distress.

Observation:

• Gross examination revealed significant amounts of watery fluid and gas within the small intestine.
• Direct smears of intestinal fluid and subsequent microscopic/electron microscopic analyses identified numerous Hexamita muris organisms.

Findings:

• Hexamita muris was observed within the intestinal crypts, mucosal epithelium, and lamina propria.
• The parasite's extensive infiltration suggests a severe mucosal disease process.

Implications:

• This study highlights Hexamita muris as a significant pathogen in laboratory mice, necessitating improved diagnostic and control strategies.
• Dimetridazole proved effective in controlling clinical signs but not in eliminating the infection, indicating the need for alternative or combination therapies.