Experimentally induced feline calicivirus infection: clinical signs and lesions.

Sixty-six specific-pathogen-free cats were allotted to 10 groups and exposed by aerosol to 10 feline calicivirus (FCV) isolates. Viruses of different virulence were identified. The more virulent FCV caused pyrexia, depression, dyspnea, pneumonia, vesicles, or ulcers of the tongue and ulceration of the hard palate and nostrils. The FCV of low virulence caused similar lesions of the tongue, palate, and nostrils but little or no malaise, pyrexia, or pneumonia. Lesions produced by FCV usually were confined to the oral mucosa, tonsils, and lungs. Lesions in the nasal or trachea were associated with 2 of the 10 FCV tested.