Feline Upper Respiratory Tract Pathogens: Herpesvirus-1 and Calicivirus University of Minnesota

Feline herpesvirus-1 and feline calicivirus are common causes of feline upper respiratory tract disease and can cause clinically indistinguishable syndromes. However, they differ in their physical properties, epidemiology, and spectrum of clinical signs; and the differences can affect the diagnosis, prognosis, and management of these infections. The availability and sensitivity of diagnostic tests also differ for each virus. Diagnosis of both infections can be difficult and is best achieved by combining patient history, physical examination, and microbiologic assay results. Treatment is primarily symptomatic. Vaccination does not prevent infection but can help minimize the severity of clinical signs and duration of shedding. Cats with both acute and chronic upper respiratory tract disease (URTD) are commonly seen in private and referral practices. The general syndrome varies in severity. When severe, it may be associated with considerable morbidity and mortality; it is therefore a concern of breeding and boarding cattery owners. Although the introduction of vaccines targeting feline herpesvirus-1 (FHV1) and feline calicivirus (FCV) in the mid-1970s may have reduced the overall disease severity, the vaccines do not prevent infection and shedding of virus and URTD may still occur. Despite the increasing availability of such molecular diagnostics as polymerase chain reaction (PCR), diagnosis and treatment of many cases of chronic feline URTDs remain frustrating. This article provides an update on the epidemiology, clinical presentations, and antemortem diagnosis and management of FHV1 and FCV, common causes of feline URTD. Chlamydophila felis (previously known as feline Chlamydia psittaci) is another common cause of feline URTD. In addition, recent research suggests that Bordetella bronchiseptica may act as a primary upper respiratory tract pathogen in cats under certain circumstances, particularly in young kittens and in overcrowded, stressful environments; however, the relative importance of B. bronchiseptica infection remains unclear. The role of Mycoplasma infection in cats with URTD is also poorly defined, and some authors suggest that Mycoplasma species mainly act as secondary invaders. CE