Cat Upper Respiratory Infection: Symptoms & Recovery Guide

Cat Upper Respiratory Infection (URI): Symptoms & Recovery

Upper respiratory infections (URIs) are arguably the most annoying—and frequent—health hurdles a cat owner will face. Whether you call it cat flu or just a nasty feline cold, these infections hit cats of all ages. They range from a few days of sneezing to serious, deep-seated illnesses that require a hospital stay. Understanding what's actually happening in your cat's sinuses is the first step toward getting them back to their playful selves.

What's Actually Going On?

Think of a feline URI as the equivalent of a human cold or sinus infection. It targets the nose, throat, and eyes. In cats, common causes include feline herpesvirus-1 and feline calicivirus, along with bacteria such as Chlamydia felis and Mycoplasma felis. The Cornell Feline Health Center's respiratory infection page and the Merck Veterinary Manual entry on Feline Respiratory Disease Complex describe these infections, their signs, and their usual supportive-care approach.

The Usual Suspects

Feline Herpesvirus-1 (FHV-1): This is one of the most common causes of feline respiratory disease. After infection, the virus can remain in the body for life and flare up during stress. Cornell reports that up to 97% of cats are exposed to feline herpesvirus in their lifetime, and that the virus causes a lifelong infection in up to 80% of exposed cats, so the share of all URI cases varies by population and should not be treated as a fixed figure.

Feline Calicivirus (FCV): This one can affect the mouth. Along with the sneezing, you may see painful ulcers on the tongue or gums. Per Cornell, roughly 10% of cats in small groups are infected, and up to 90% in crowded conditions such as shelters or catteries.

Bacterial Tag-Teams: Viruses can be complicated by secondary bacterial infections. You might hear your vet mention:

• Chlamydia felis
• Bordetella bronchiseptica
• Mycoplasma felis

How It Spreads (It's Fast)

Cat flu is highly contagious. It moves through:

• The "Slow Blink" Range: Direct nose-to-nose contact.
• The Sneeze Zone: Tiny droplets flying through the air after a sneeze.
• Shared Stuff: Food bowls, brushes, and even your own hands can carry infectious material from one cat to another.
• The Silent Carrier: Some cats look perfectly healthy but may shed virus intermittently, especially during stress.

Spotting the Signs

Symptoms change depending on the cat's age and how strong their immune system is. If you're seeing common cat health problems like these, pay close attention.

What to Look For

The Nose:

• Non-stop sneezing fits.
• Goopy discharge, which may begin clear and become thicker or colored.
• A "stuffy" sound when they breathe or open-mouth breathing.

The Eyes:

• Squinting or "winkey" eyes.
• Red, angry-looking membranes (conjunctivitis).
• Shmoo or crust building up in the corners.

The Rest of the Body:

• Drooling, which can occur with painful mouth sores.
• Just acting "blah"—lethargic and hidey.
• Turning their nose up at food if congestion or mouth pain reduces their appetite.

Red Flags: When to Hit the Emergency Vet

Don't wait if you see:

• True gasping or labored breathing.
• Your cat hasn't eaten a single bite in 24 hours.
• They're so weak they can't stand.
• A measured temperature over 105°F. Feeling a cat's ears or body is not a reliable way to confirm fever.

Cornell notes that difficulty breathing is uncommon but serious, and a resting respiratory rate above about 35 breaths per minute warrants prompt veterinary assessment. The Merck Veterinary Manual confirms fever may reach 105°F (40.5°C) during the acute phase.

What URI Day-to-Day Actually Looks Like

Based on the patterns the Cornell Feline Health Center and the Merck Veterinary Manual describe in clinical cases, mild URIs usually run their course in 5–10 days, while tougher infections can stretch to about six weeks. In real homes, the typical arc plays out something like this:

• Days 1–3: A sudden burst of sneezing, clear eye discharge, and slightly lower energy. Appetite is usually still present, but the cat may paw at the face or sneeze in long fits.
• Days 4–7: Discharge thickens and may turn yellow or green if a secondary bacterial infection sets in. Mouth breathing can show up if the nose is badly congested, and many cats start turning their nose up at kibble.
• Days 7–14: Symptoms either taper off, or—in tougher cases—the cat develops mouth ulcers, persistent fever, or eye changes (squinting, corneal involvement) that need a vet's eye.
• After recovery: Herpesvirus carriers can have flare-ups triggered by stress—boarding, a new pet, moving, or even a routine vet visit.

This rough arc is what most adult, vaccinated cats follow. Kittens, seniors, and brachycephalic breeds may not follow the same timeline, and any deviation toward breathing trouble or a 24-hour food strike is a reason to call your vet.

Who's Most at Risk?

While any cat can catch a cold, some have a much harder time fighting it off, potentially leading to pneumonia:

• Kittens: Their immune systems are still developing, making them more vulnerable.
• Seniors: Older cats may have a harder time recovering.
• The "Smush-Faced" Crew: Persians and Himalayans have shortened facial anatomy and may be at higher risk for chronic respiratory disease. The Merck Veterinary Manual specifically identifies brachycephalic breeds as having a higher risk of chronic disease.

At the Vet: Getting Answers

Your vet will start by checking for mouth ulcers, eye and nasal discharge, breathing changes, hydration, and other signs. If the case is stubborn or severe, they might suggest:

PCR Testing: A swab or other sample may help identify the genetic material of a virus or bacterium.

Bacterial Culture: This can help identify bacteria and guide antibiotic selection when bacterial infection is suspected.

Blood Work: This may be recommended when the veterinarian needs to investigate other health problems, including conditions that could weaken the immune system.

Testing does not always identify a single cause, and your veterinarian will interpret results alongside the cat's signs and history. The Merck Veterinary Manual explains that diagnosis may combine clinical signs with laboratory testing.

Helping Your Cat Heal

Home Care Support

Most uncomplicated viral infections need time and supportive care:

• The Steam Treatment: Bring your cat into the bathroom while you take a hot shower. Humid air may help loosen nasal secretions, but keep your cat away from hot water and stop if they become stressed.
• Stinky Food Is Good Food: Since congestion can reduce their ability to smell, gently warming wet food may make it more appealing. Never serve food hot.
• The Warm Compress: Use a soft, damp cloth to gently wipe away eye crust.
• Hydration: Encourage normal drinking and offer wet food. If your cat is not drinking or eating, contact your veterinarian rather than relying only on home remedies.

Both Cornell and Merck emphasize maintaining nutrition and hydration and gently clearing nasal or eye discharge as important supportive measures.

Meds That Help

Antibiotics won't kill a virus, but a veterinarian may prescribe them when a secondary bacterial infection is suspected. Famciclovir or another antiviral may be considered in some feline herpesvirus cases. Cornell's respiratory-infection guidance discusses supportive care, antibiotics for secondary bacterial infections, and antiviral treatment in selected cases.

A note on L-lysine: L-lysine has long been recommended as a supplement for cats with feline herpesvirus, but a 2015 systematic review in BMC Veterinary Research concluded that lysine supplementation is not effective for preventing or treating FHV-1 and may actually worsen symptoms or viral shedding. Cornell likewise describes lysine as controversial. Talk to your vet before starting any supplement, and don't rely on lysine in place of vaccination or supportive care.

Medication names and use are informational; always follow your prescribing veterinarian's instructions. Do not give your cat leftover antibiotics, human cold medicine, or any medication without veterinary guidance.

The Bill: What to Expect

These ranges are drawn from publicly available cost references, including the RealVetCosts URI in Cats page and the CareCredit veterinary pricing guide, along with typical SpectrumCare PCR test pricing. They are rough, illustrative estimates rather than a current price quote. Actual costs vary widely by geographic region, clinic type, diagnostic needs, emergency status, and the medications prescribed. They were compiled for general planning in 2026; ask your clinic for a local estimate before treatment.

Keeping It Away

The Vaccine: The FVRCP shot is a core vaccine for cats. It does not prevent every infection, but vaccination can reduce the severity of disease. The 2020 AAHA/AAFP Feline Vaccination Guidelines identify FHV-1 and FCV as core vaccine targets for pet and shelter cats, while Cornell notes that vaccination reduces severe disease and viral shedding without preventing every infection.

The New Guy: If you bring a new cat home, keep them in a separate room and ask your veterinarian how long separation and monitoring should last. No isolation period can guarantee that a cat is not carrying an infection.

Keep It Chill: Stress can contribute to herpesvirus flare-ups, so keep the environment calm and routines consistent. Ask your veterinarian before relying on supplements or products marketed for immune support.

Whatever you do, don't panic if you hear a sneeze—many cats recover from uncomplicated URIs with supportive care. Keep a close eye on appetite, hydration, energy, and breathing.

This article is informational and is not a substitute for veterinary advice. A veterinarian should assess any cat with breathing difficulty, severe lethargy, dehydration, persistent symptoms, or loss of appetite. Any personalized guidance offered through our on-page AI assistant is generated by an automated tool and is not a substitute for hands-on veterinary examination.

About the Author

This article was reviewed by the Cat Care World veterinary review panel, which is led by Dr. Sarah Chen, DVM, a licensed small-animal veterinarian. Our health content is developed in consultation with practicing veterinarians and reflects current standard-of-care guidance from sources such as the Cornell Feline Health Center, the Merck Veterinary Manual, and the AAHA/AAFP Feline Vaccination Guidelines.

While a "cat cold" might seem like no big deal, it can spiral quickly if your cat stops eating or drinking. Most of the time, your job is just to be a good nurse: keep their face clean, the air comfortably humid, and the food appealing. But if they're struggling to catch their breath or seem totally wiped out, skip the home remedies and call your vet immediately. Prevention through an individualized FVRCP vaccination plan remains an important part of long-term respiratory health.