Sinus Infections in Cats

What Is a Sinus Infection in Cats?

Sinuses are air-filled sacs within the skull and the nasal cavity that are interconnected. They are lined with mucus membranes that filter out germs, pollens, dust, and debris. Any obstruction or destruction of the membranes can cause those irritants to remain in place, leading to a sinus infection.

 Just like in humans, sinus infections are debilitating and can cause pain, fever, lethargy, and a diminished sense of smell. They can also cause a temporary loss of appetite, as the sense of smell in cats is more of a driving force for eating than their sense of taste.

Sinusitis is termed an “inflammation of the sinus” lining, and rhinitis is termed an “inflammation of the nasal passages.”  Both often occur simultaneously and are common complications of upper respiratory tract disorders in cats.

Symptoms of Sinus Infection in Cats

Cats with sinus infections often have eye or nasal discharge or both, which can vary in consistency and color. They may sneeze, have a decreased appetite, and act withdrawn or lethargic.  Other symptoms accompanied with sinus infections can include:

• Labored breathing or a change in vocalization (meows may sound different)

• Nasal congestion

• Snoring

• Protrusion of the third eyelid, or cherry eye

• Conjunctivitis, or “red eye”

• Fever

• Changes in behavior

• Swelling and/or asymmetry to the nose and face

• Difficulty swallowing or gagging

• Eye or mouth ulcers

• Enlarged lymph nodes beneath the jaw

• Reluctance to pet or touch the face and head

• Neurologic symptoms, such as seizures and head tilting

Causes of Sinus Infection in Cats

Kittens and immunocompromised cats are more at risk, but any age or breed of cat can develop a sinus infection. The causes are numerous, but most cases of sinus infections are considered infectious by nature. Causes can include:

• Infectious

  • Viral

  • Bacterial

  • Fungal

  • Nasal mites

• Allergic—an uncommon cause, which is usually seasonal due to high pollen counts, but can occur year-round if attributed to household dust and molds

• Dental disease such as tooth root abscess or oronasal fistula

• Nasopharyngeal polyps

• Foreign objects such as plant seeds or blades of grass

• Trauma

• Cancer (lymphoma and adenocarcinoma, more common in cats)

How Veterinarians Diagnose Sinus Infections in Cats

Since there are numerous causes for why a cat may have a sinus infection, diagnosing the underlying reason correctly is critical. The first thing your veterinarian may recommend after a physical exam is basic blood work, like a complete blood cell count (CBC), internal organ function screening, and retroviral testing (FeLV/FIV) to assess your cat’s overall health and provide possible therapy options. The results can also assist with surgical and anesthetic planning and help rule out other conditions.

From there, your veterinarian may then recommend a test that looks for trace DNA of infectious organisms; it is useful for screening and can provide future health implications if your cat is infected with feline herpesvirus. 

Radiographs or CT scans of the head and chest may be recommended to assess the nasal passages, sinuses, and lungs for potential masses or bony changes that can indicate chronic infection or cancer. Dental radiographs while under anesthesia may also be necessary to evaluate the extent of dental disease and tooth root abscess. 

Additionally, a rhinoscopy may be required. This is when a small camera is inserted inside the cat’s nose to visualize the nasal and sinus cavities. Biopsy samples can also be taken for further testing and analysis during this procedure.

Treatment of Sinus Infections in Cats

Treatment depends on the underlying cause. Antiviral medications such as famciclovir may be prescribed for cats with feline herpesvirus, and antibiotics such as Clavamox®, doxycycline, or clindamycin may be prescribed for bacterial infections. Fluconazole or itraconazole (antifungal medications) may be prescribed for fungal infections.

Although typically not given as a first line of defense, anti-inflammatories or steroids may also be needed to reduce swelling and mucus production—these can also be prescribed in cases of chronic sinusitis. 

Treatment options for cancer include surgery, chemotherapy, radiation, or a combination.  Nasopharyngeal polyps are surgically removed.

Cats with sinusitis due to an infected tooth generally require general anesthesia and a dental cleaning, with surgical extraction of the infected tooth. 

Secondary supportive care measures often include:

• Fluids given intravenously to combat dehydration
• Appetite stimulants such as Elura™ or mirtazapine to help with loss of appetite
• A temporary change in diet that may include warming the food first to make it more appetizing
• Wiping discharge from the eyes and nose
• At-home therapy may consist of steam therapy or using a nebulizer with saline. 

To prevent possible disease transmission, your cat may need to be isolated from any other cats in your home until the cause can be identified.

Recovery and Management of Sinus Infections in Cats

Cats with a favorable prognosis often respond to the above medications within a few days, with most treatment duration lasting two weeks. Some infections (such as fungal ones) can take months of treatment to show improvement.

Prevention of Sinus Infection in Cats

Not every sinus infection is preventable, but there are certain steps pet parents can take to minimize or reduce the chances of your cat getting one. Keeping your cat indoors reduces the risk of exposure to infectious organisms, and be sure to keep them up to date on vaccinations and routine veterinary check-ups. Avoid exposure to inhaled irritants and smoke, and improving the air quality of your home with regular household filters, as well as a clean environment, can lessen the risk overall.

A relatively stress-free lifestyle for your cat is also important, especially for those infected with herpesvirus, as it can reoccur and many cats will remain carriers for life. Cats with allergies can develop future infections—and getting a sinus infection once does not mean your cat will never get one again.