Most mild ailments in cats don’t require immediate veterinary care, but an eye issue isn’t one of them. Cat eye infections can dramatically worsen in just a few hours, which makes bloodshot eyes worthy of a call to your vet.
To help your vet diagnose the cause of red cat eyes, you’ll want to make note of your cat’s additional symptoms, behavioural changes, and other stand-out issues you may have noticed. Make note of any recent physical traumas, potential environmental irritants, and eye changes, such as swelling or discharge.
Read on to learn the associated symptoms and causes behind why your cat’s eyes might be red. Plus, we ask experts if human eye drops are safe to alleviate your cat’s red, itchy eyes. (Spoiler, they’re not.)
Causes of Red Eyes in Cats
1. Your cat has allergies
Allergies in cats can look, and feel, a lot like those in humans. Like us, cats can have seasonal or year-round allergies caused by dust, pollen, or grass. Allergies in cats can cause watery eyes and other symptoms, such as:
- coughing, sneezing, and wheezing
- rash or itchy skin
- disrupted digestive system (vomiting, diarrhoea, and gas)
If your indoor cat has red, itchy eyes, you may want to try a dust-free litter or discontinue using any harsh chemical cleaning products in your home that could be a source of your cat’s eye irritation.
2. Your cat has conjunctivitis
Feline conjunctivitis, or cat pink eye, is an infection that causes inflammation to the membrane that surrounds the surface of your pet’s inner eyelid and around the eyeball. Pink eye can be caused by an infection from a virus, bacteria, or fungus, with feline herpesvirus being a leading cause.
There are two kinds of pink eye; infectious and non-infectious. Infectious pink eye can quickly spread from cat to cat and even to dogs, so keep pets that are infected separated. Non-infectious pink eye may be caused by irritants like particles of dust, stray hairs, or allergies.
All felines can become infected with kitty pink eye, but it is more common in younger cats and kittens. If your cat has conjunctivitis, you may also notice:
- red, irritated eyes—sometimes with discharge
- inflammation of the pale pink eye tissue
- squinting and blinking
- sneezing or runny nose
- coughing
Pink eye can not be spread from cats to humans. But, if you have a multi-cat household, you may want to consider separating your kitty to prevent infection to the other cats in your clowder.
3. Your cat has dry eye
Dry eye, or keratoconjunctivitis sicca, is when your cat isn’t producing enough tears to protect the eye from drying out and becoming inflamed. Apart from red, irritated eyes, you may also notice symptoms of:
- squinting, blinking, or shutting of eyes
- dull appearance to the eyes
- yellowish discharge
Cat dry eye is caused by many conditions:
- Damage to the tear-producing glands
- Systemic diseases, like feline herpesvirus
- Side effect or adverse reaction to a medication
- Inner ear infection causing neurological symptoms
To treat dry eye, your vet may prescribe medication to help stimulate tear production and recommend you clean your cat’s eyes with a clean, warm, and wet cloth to reduce irritation. Dry eye is important to treat immediately as it can cause corneal scarring, which may lead to vision damage.
4. Your cat has glaucoma
More common in dogs than in cats, glaucoma is a condition that is caused by increased pressure in the eye. This increased pressure is caused by an imbalance of production and drainage of the fluid within the eye, and can result in vision loss.
“When it comes to glaucoma, signs of this condition can vary based on the stage,” explains Dr. Rebecca Greenstein, DVM, chief veterinarian of Kleinburg Veterinary Hospital and veterinary medical advisor for Rover.
Early stages of the disease in cats might include:
- red, bloodshot eyes
- abnormal discharge
- swelling of the eyeball
- cloudiness in the eye
- behavioural changes, such as disinterest in activities
The symptoms increase in severity over time, which can be painful for your pet and can lead to blindness. While glaucoma can’t be cured, there are many ways to manage and relieve the pain and slow the progression of this disease.
5. Your cat has uveitis
Whereas glaucoma refers to increased pressure in your cat’s eye, uveitis refers to decreased pressure. Uveitis is the inflammation of your cat’s iris, choroid, and ciliary body, affecting the way your cat’s eye gets nutrients and maintains eye pressure and vision.
Symptoms of uveitis may include:
- pawing at the eye due to the pain
- difficulty seeing
- redness in the whites of the eyes
- cloudy appearance to the eyes
- clear discharge
There are a lot of potential causes of uveitis, which may include:
- bacterial or viral infections
- metabolic disease (like diabetes)
- high blood pressure
- chemical or physical irritants
- autoimmune disease
- physical injury to the eye
- eye tumours
Treating uveitis depends on the cause, although it’s not uncommon not to be able to diagnose one. Infections will require medication while traumatic injuries may require surgery. Your vet’s first priority will likely be to help reduce further complications and manage any pain.
Photography by Adri/iStock
6. Your cat has a corneal ulceration
A corneal ulceration is a scratch or tear in the transparent front part of the eye. Physical trauma like a scratch to the eye or accidental eye contact with a sharp object are the most common causes. Infections and cat flu can also be to blame. And, if your cat has a tendency to get into your bathroom cabinet, they may be at risk of a chemical burn to the eye.
While the symptoms look a lot like other eye injuries and infections—redness, discharge, and a funny-looking wink—corneal ulceration is very painful. Call your vet immediately if you notice your cat pawing at their red eye. Only your veterinarian can determine the extent of the injury and prescribe the needed care.
7. It’s your cat’s eyeshine
You’ve probably seen eyeshine in a photograph of your cat or when they are creeping around the house at night. But did you know that the colour of the eyeshine depends on the colour of a cat’s eyes?
“Cats with gold eyes will have a green reflection and will glow green whereas a cat that has blue eyes will glow red or orange,” Hannah Sotropa, assistant manager of Toronto Humane Society, tells Rover.
In low-light settings, a structure in your cat’s eye called the tapetum reflects light of a certain colour from the back of their eye. So, if you see glowing red eyes when you sneak down for a midnight snack, it might just be your cat’s big blue eyes watching you.
If you are the proud parent of an albino kitty with no pigment in her eyes, then you’re probably seeing the red glow of her blood vessels. If the colour of your cat’s eyeshine is new or different, let your vet know right away.
Can I Give My Cat Human Eye Drops for Her Eye Infection?
No, don’t share your human eye drops with your cat unless specifically advised to by your vet.
When it comes to any type of medication for your cat’s eyes, Laura Jones, DVM, strongly advises that “eye medications should never be given under any circumstance without explicit directions from a veterinarian. If used inappropriately, many eye medications can cause new problems or worsen existing problems.”
It’s always best to consult your vet for the proper cat eye infection treatment.
When to Go to a Vet for a Red Eye Diagnosis
If your cat’s eyes are red, irritated, have unusual discharge, or are different in appearance, schedule a visit with your vet right away because your cat most likely has an eye infection. When it comes to the eyes, Dr. Jones says “there is no situation that you should wait and see.”
The Takeaway
There are a lot of reasons why your cat’s eyes could be red. But they all have one thing in common: they need to be treated by your vet sooner rather than later. If your vet prescribes medication, follow the instructions until the last day. Don’t forget to ask your vet about the best way to clean your cat’s eye regularly to help reduce contamination and discomfort.
Other than keeping your cat up to date on all vaccines and on a regular check-up schedule with the vet, it may also help to regularly clean your house to reduce airborne irritants and to cat-proof certain areas to prevent accidental exposure to chemicals. Perfumes, cleaning products, cigarette smoke, and even household dust may be irritating your cat’s eyes.
