Feline respiratory virus carriers in clinically healthy cats.

In two surveys, feline calicivirus was cultured from 19.7% and 15% of 66 and 201 clinically healthy cats respectively. Feline viral rhinotracheitis virus was cultured also from 1.5% of oropharyngeal swabs collected in both surveys. Feline syncytial virus was isolated from 5.5% oropharyngeal swabs collected in the second survey. The use of serological examination and corticosteroid treatment to stimulate virus shedding demonstrated that 25.8% cats in the first survey were carriers of feline viral rhinotracheitis virus. In the second survey, mercapto-ethanol treatment of serum was used to differentiate recent from previous infection with feline viral rhinotracheitis virus and some 18.5% cats had FVR antibody that was resistant to treatment with mercapto-ethanol.