What are nasal polyps?
Nasal polyps are benign (non-cancerous) fleshy growths that develop in the nasal passages of cats. In addition to the nasal passages, similar polyps can occur in the area above the soft palate (the roof of the mouth) or within the ear canal.
Nasal polyps originate from the cells that line the nasal passages. These polyps are composed mostly of inflammatory cells, covered by a layer of epithelial cells (modified skin cells) that extend over the surface of the polyp. Polyps may be up to 1-2 cm in length, extending into the nasal passages or the ear canal.
Nasal polyps are most frequently observed in young cats. Older cats, however, may also be affected. Nasal polyps can occur in cats of any breed.
What causes nasal polyps?
The cause of nasal polyps is not fully understood. A genetic predisposition is suspected, with some cats being more likely to develop nasal polyps due to hereditary factors. It is also thought that certain infections may play a role in the development of nasal polyps by triggering inflammation.
What are the clinical signs of nasal polyps?
The clinical signs of nasal polyps can vary depending on the location of the polyp. The signs of nasal polyps often mimic an upper respiratory infection; however, these signs may persist with little response to medical therapy.
"The signs of nasal polyps often mimic an upper respiratory infection..."
Commonly observed clinical signs include sneezing, increased respiratory sounds, and nasal congestion. Affected cats may have trouble breathing. You may also notice decreased airflow through the nostrils if you place your hand in front of your cat’s nostrils or watch as they breathe onto a piece of glass. In a cat with healthy nasal passages, you should see two small clouds of condensation when they breathe on glass – one at each nostril. If a nostril is obstructed, you may only see one area of condensation. In some cases, you may see discharge from the eyes and/or nose.
In some cases, nasal polyps may extend from the nasal passages into the throat. These nasopharyngeal polyps can cause more severe clinical signs, including increased difficulty breathing and swallowing. Cats with nasopharyngeal polyps also may develop clinical signs related to their ears, frequently tilting the head to one side, pawing at the ears, or developing frequent or recurrent ear infections.
How will my veterinarian diagnose nasal polyps?
Nasal polyps may be observed on careful examination, which may need to be performed under sedation. In other cases, specialized tools such as rhinoscopy (a camera passed down the nasal passages) or endoscopy (a camera passed into the throat) may be required to visualize nasal polyps.
In some cases, further imaging is required to diagnose nasal polyps. Your veterinarian may perform radiographs (X-rays) of your cat’s skull (under sedation or general anesthesia) or may recommend a CT scan or MRI to better evaluate the nasal passages.
How are nasal polyps treated?
Nasal polyps can often be surgically removed with traction or avulsion (pulling or tearing). With your cat under general anesthesia, your veterinarian will use forceps to grip, twist, and pull the polyp free from its attachment.
"Nasal polyps can often be surgically removed with traction or avulsion."
Laser ablation (removal of the polyp using a laser beam) and other specialized techniques can also be used for the treatment of nasal polyps. These techniques are less commonly used but may be beneficial in some cases.
In some cases of polyps in the ears, a surgical technique called a ventral bulla osteotomy may be used. This involves opening the hollow chamber of the skull below the ear to remove the polyps more completely to significantly reduce recurrence.
Following the removal of the polyps, your veterinarian may prescribe antibiotics to prevent infection of the surgical site. Additionally, your veterinarian may prescribe a gradual tapering dose of a steroid (such as prednisone) to decrease inflammation and reduce the likelihood of the polyp recurring.
What is the prognosis for nasal polyps?
Polyps removed with traction or avulsion have a 15-50% likelihood of recurrence. Because the underlying factors that contribute to nasal polyps are unknown, there is no effective method for preventing recurrence. If your cat’s nasal polyps do recur after treatment, these polyps will also need to be surgically removed.