In a cat with fever, nasal discharge, and ocular signs, name two common etiologies of upper respiratory infection and a recommended initial diagnostic test.

• A. Feline panleukopenia and chlamydial infection; PCR on fecal samples
• B. Feline upper respiratory infection complex (herpesvirus and calicivirus) or secondary bacterial infection; PCR on ocular/nasal swabs
• C. Canine infectious tracheobronchitis and influenza; PCR on blood samples
• D. Fungal rhinitis and cryptococcosis; radiographs only

Answer: (B)

Upper respiratory infections in cats are most often viral, with feline herpesvirus-1 and feline calicivirus as the usual culprits. When a cat presents with fever, nasal discharge, and ocular signs, quickly identifying a viral cause helps guide treatment and infection control. The recommended initial diagnostic test is PCR on ocular and nasal swabs because it directly detects the viruses from the sites they replicate, is sensitive, and provides fast results. Sampling both nasal and ocular routes increases detection if shedding varies. A positive result supports a viral diagnosis and can influence management (antivirals for herpesvirus, supportive care for calicivirus) and decisions about antibiotic use. Other possibilities are less fitting here: fecal PCR wouldn’t assess these URIs, and the pathogens listed in the other options are either not typical feline URIs or require different tests, such as blood tests or imaging, rather than an initial viral swab PCR.