**Association of Bordetella bronchiseptica with URTD in cats**

A UK survey (McArdle et al 1994) measured seroprevalence of Bordetella bronchiseptica in a variety of cat households. Prevalence of antibodies to Bordetella bronchiseptica (Bb) in cats with a history of URTD was approximately 85%, compared to approximately 30% in cats with no such history. These findings indicate that past exposure to the bacterium was not incidental but associated with disease.

Bb is a primary respiratory pathogen
It is known that Bb can act as a primary respiratory pathogen in cats. Kittens challenged with an aerosol of Bb developed signs of respiratory disease, characterised by nasal discharge, sneezing, spontaneous or induced coughing and dry or wet rāles on auscultation. These symptoms developed within 5 days and persisted for 10 days, after which they began to resolve.

Field studies support this finding. In 1991 Elliot et al investigated a closed breeding colony undergoing an outbreak of respiratory disease. They failed to isolate FHV or FCV from these cats and found titres to Chlamydophila felis were low. Cats showed symptoms very similar to those of canine kennel cough and Bb could be isolated from the cats with respiratory symptoms, but not from the healthy cats. This suggests that Bb was the principle pathogen.

Attempts have also been made to isolate Bb from oropharyngeal swabs taken from cats with or without signs of URTD (McArdle et al 1994). Bb could only be isolated from cats with URTD, or those which had been in contact with such cats. Furthermore it was found that the prevalence of antibodies to Bb in cats with a history of URTD is far higher than in cats with no such history (approximately 85%, compared to approximately 30%). These findings show that past exposure to Bb is not incidental but clearly associated with URTD.