INFECTIOUS CATARRH OF THE ALBINO RAT : II. THE CAUSAL RELATION OF COCCOBACILLIFORM BODIES

Area of Science:

• Veterinary Pathology
• Microbiology
• Infectious Diseases

Background:

• Infectious catarrh is a common respiratory ailment in laboratory rats.
• The causative agent of rat infectious catarrh has not been definitively identified.
• Previous studies suggest similarities to agents causing other animal coryza.

Purpose of the Study:

• To identify the causative agent of infectious catarrh in rats.
• To characterize the morphology and biological properties of the identified agent.
• To demonstrate the reproducibility and transmissibility of the disease experimentally.

Main Methods:

• Microscopic examination of nasal and middle ear exudates from affected rats.
• Isolation and culture of the suspected causative agent.
• Intranasal inoculation of cultured agent into healthy rats to reproduce the disease.
• Serial passage of the infectious agent through rats.
• Transmission studies via direct contact.

Main Results:

• Gram-negative coccobacilliform bodies were identified in over 90% of exudates.
• Pure tissue culture growths of these bodies reproduced the characteristic syndrome in rats.
• The disease was maintained through 10 serial passages.
• Experimentally induced disease was communicable by direct contact.
• The agent's characteristics were discussed in relation to the pleuropneumonia group organisms.

Conclusions:

• Gram-negative coccobacilliform bodies are the causative agents of infectious catarrh in rats.
• The identified agent shares similarities with agents of fowl coryza and mouse catarrh.
• Experimental reproduction and transmission confirm the etiology and infectious nature of rat catarrh.