Sudden Unilateral Eye Tears in Cats: Possible Causes

When a cat suddenly starts to tear up from just one eye, it can be a physiological response to an irritant, or it might be indicative of pathogenic factors such as eye infections, injuries, or structural anomalies. If the symptoms persist for an extended period, it's crucial to be vigilant and promptly identify the cause, followed by targeted treatment to ensure the cat's ocular health.

1. Foreign Body Irritation

Occasionally, fine dust, fur, or other particles may enter a cat's eye. These foreign bodies can irritate the cornea, prompting an increase in tear production as the body attempts to flush out the irritant.

How to Handle:

● Typically, if the tears can wash away the foreign object, the cat will stop tearing up.

● If the foreign object remains stuck, we can use sterile saline solution or petspecific eye care solutions to flush it out. If it's too difficult to remove, it's best to consult a veterinarian to avoid damaging the cat's eyes by picking at it with your fingers.

2. Conjunctivitis

The conjunctiva is a thin, transparent membrane covering the inner eyelids and the surface of the eye. When it's irritated or infected by bacteria or viruses, conjunctivitis can occur, leading to redness, pain, difficulty opening the eyes, and excessive tearing.

How to Handle:

● Use saline solution to rinse the cat's eyes, removing tears, secretions, and debris. Then, apply Beranming (neomycin sulfate eye drops) or ofloxacin eye drops three to five times a day, one to two drops each time.

● For bacterial conjunctivitis, improvement can be noticeable within one to three days of treatment.

● If home remedies are ineffective or the cat exhibits other symptoms like sneezing, fever, or loss of appetite, it's advisable to take it to a veterinary clinic for a checkup to determine if the cat has contracted feline rhinotracheitis or another illness.

3. Corneal Injury

Injuries or ulcers to the cat's cornea can also cause an increase in tears, accompanied by symptoms like cloudy cornea, increased secretions, photophobia, eye pain, and loss of appetite.

How to Handle:

● This condition is quite painful and requires immediate veterinary attention. If left untreated, it can lead to more severe issues, including blindness.

4. Nasolacrimal Duct Obstruction

Under normal circumstances, excess tears from a cat's eyes should flow through the nasolacrimal duct into the nose. If one tear duct is blocked, tears cannot be expelled normally, accumulating around the eye socket and causing a single eye to tear up. The blockage could be congenital or due to inflammation, tumors, or trauma.

How to Handle:

● Visit a veterinary clinic for an examination. If the blockage is due to inflammation or trauma, the nasolacrimal duct can be flushed and cleared, followed by antibiotic treatment to control infection.

● If the blockage is caused by congenital malformation of the nasolacrimal duct, tumors, or other issues, surgical intervention may be necessary.

5. Trauma

When a cat's eyes are struck, scratched, or squeezed during fighting or play, it can lead to local soft tissue damage, resulting in symptoms like tearing, redness, and swelling.

How to Handle:

● Use sterile saline solution to rinse the eyes, removing blood and dust.

● Under veterinary guidance, administer nonsteroidal antiinflammatory drugs and antibiotics to the cat.

Besides the aforementioned common causes, upper respiratory infections, dental issues, ear mites, otomycosis, ingrown eyelashes, or immune systemrelated conditions can also lead to a cat suddenly tearing up from one eye. If you're unable to determine the cause or find a solution, it's best to consult a veterinarian promptly.