There is little argument among veterinarians that feline viral upper respiratory disease is perhaps the most common respiratory
disorder for which cats are presented. In multiple-cat households and animal shelters world-wide, transmissible feline upper
respiratory disease (URD) represents the most prevalent clinical disease in the population of cats at risk. The question that must be asked is: despite widespread
use of vaccines against viral (herpesvirus and calicivirus) and bacterial (Chlamydophila felis and Bordetella bronchiseptica) respiratory disease, why do these infections persist? ...and, what can be done to effectively manage these infections within
This question is important, but today there are answers that will help veterinarians manage the infected cat and minimize
spread of infections among cats living within a closed population. This presentation addresses the most common cause of both
acute and chronic upper respiratory infection in cats: feline herpesvirus-1 (cause of feline rhinotracheitis) and feline calicivirus.
From diagnosis, to clinical management of infected cats, to vaccination...the critical issues surrounding this respiratory
complex will be discussed.
Several infectious organisms are known to produce clinical signs of upper respiratory disease (URD) in cats. The most important,
and most common, are:
• Feline Herpesvirus-1 (FHV-1)
• Feline Calicivirus (FCV)
• Chlamydophila felis (formerly, Chlamydia psittaci)
• Bordetella bronchiseptica
Reports on the prevalence of individual pathogens in outbreaks of feline respiratory will vary from country to country. In
the United Kingdom, for example, it has been estimated that Chlamydophila felis infections constitute up to 30% of the cases of respiratory disease in cats. In North America, it's estimated to cause fewer
than 5% of cases of feline respiratory disease. Today, most authors agree that between 80% and 90% of the cases of feline
viral URD are caused by one of two viral groups, either (FHV-1), cause of feline viral rhinotracheitis (FVR), or feline calicivirus
(FCV). Although a number of other viruses (cat pox, FeLV and FIV) and bacteria (Haemophilus felis, Mycoplasma spp.) have been shown to be associated with clinical signs of respiratory disease in cats, their clinical importance is largely
linked to either herpesvirus or calicivirus infection...and occasionally, both!