Cat Upper Respiratory Infection: Symptoms, Treatment, and When to Worry

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A sneezing cat with a runny nose might just be reacting to dust — or it might be the start of an upper respiratory infection (URI) that needs prompt care. Cat URIs are among the most common illnesses in cats, especially in those who have spent time in shelters or around other cats.

What Causes Cat URIs?

The majority of feline URIs are caused by feline herpesvirus (FHV-1) and feline calicivirus (FCV) (Helps et al., 2005, JFMS). Bacterial infections — particularly Chlamydophila felis and Bordetella bronchiseptica — can occur alongside or independently. The viruses spread through direct contact, shared bowls, and airborne droplets.

Important note: once a cat is infected with herpesvirus, the virus remains dormant for life. Stress can trigger reactivation and recurrent flare-ups.

Symptoms of a Cat URI

Mild to Moderate

• Sneezing — often repeatedly and in fits
• Nasal discharge — clear initially, then yellow or green
• Eye discharge — watery or crusty; one or both eyes may be squinting
• Mild congestion
• Reduced appetite due to inability to smell food
• Lethargy

Severe Signs

• Difficulty breathing or breathing with open mouth
• No eating or drinking for 24+ hours
• High fever
• Ulcers in the mouth (sign of calicivirus)
• Loud wheezing or rattling sounds

When to Worry: Emergency Signs

Get your cat to a vet immediately if they:

• Are not eating or drinking at all
• Are breathing rapidly or with obvious effort
• Have significant eye discharge with visible corneal cloudiness
• Are extremely lethargic and unresponsive
• Are a kitten — young cats can deteriorate very quickly

What to Do at Home

For mild symptoms in an otherwise healthy adult cat:

• Keep the nose and eyes clean with a warm, damp cloth
• Run a humidifier or let your cat breathe steam in the bathroom
• Warm the food slightly to help entice a congested cat
• Ensure fresh water is always accessible
• Keep the cat warm, quiet, and away from stress

Never give human cold medications to cats — many are toxic.

Still Not Sure if Your Cat Needs a Vet?

When you're not sure if this is wait-and-see or call-tonight, Voyage AI Vet triages in under 2 minutes. Describe what you're seeing in chat, share photos of your cat's chest movement and any nasal discharge or open-mouth breathing, or hop on a live video call if you want a second pair of eyes. Every answer comes with citations to the actual veterinary literature it's pulling from — so you see exactly where the guidance comes from, not just a chatbot's word.

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