Why Does My Cat Have Dilated Pupils
See files for Cats
In addition to body language, cats use their eyes to communicate. Facial expressions are used to intimate meaning to us, other cats and animals of different species. For many, a felines gaze is one of the most mysterious. This is often due to characteristic depth of their pupils. This is especially so when they are dilated. But exactly what does it mean if they are completely round?
In general, pupils of cats tend to resemble a vertical line, not a circle. It is not surprising that when witnessing this change cat guardians become alarmed. In this AnimalWised article we will discuss why your cat has dilated pupils by showing its meaning and the main causes.
So What Was The Cause For Such A Dramatic Difference In Pupil Size
My first thought was Horners syndrome, a condition where the innervation to the pupil is disrupted, causing the pupil in the affected eye to become smaller. However, with Horners the third eyelid tends to elevate a little in the affected eye which was not present in Toby here.
As with the physical exam, a thorough ocular exam is essential. Both eyes were examined with an ophthalmoscope to get a better look. A Schirmer tear test was performed to look for inadequate tear production. A blood pressure was taken since hypertension can cause vision issues. Numbing drops were applied to the eyes and the ocular pressures were taken. The pressure in the larger pupil measured 50 mmHg and the small one 15 mmHg. 20 mmHg is considered the higher end of normal and if there is a difference of 10% pressure in the eyes that is significant.
To our surprise, the eye with the smaller pupil was the normal one. The eye with the larger pupil had glaucoma.;
What Is Glaucoma?
Glaucoma is another common cause for differing pupil size in cats. Glaucoma is a condition in which increased pressure exists inside the eye. The affected eye has a larger pupil and will often bulge from the eye socket. Glaucoma is not common in cats and can be painful. In extreme cases, it can result in blindness.;
How To Manage Dilated Pupils
If a medicine caused your pupils to dilate, they should go back to normal once the drug wears off. Try to avoid the drug in the future, if you can. If you need the medication for a health problem, ask your doctor if thereâs a different drug you can try that wonât affect your eyes.
While your eyes are dilated, they will be more sensitive to light than usual. Try to avoid bright places. Wear sunglasses when you go outside. Sometimes dilated pupils can affect your vision. Ask your eye doctor if you need to avoid driving until your pupils go back to their normal size.
American Academy of Ophthalmology: “Pharmacologic Dilation of Pupil,” “What Can Cause A Fixed Pupil?” “What to Expect When Your Eyes Are Dilated.”
Benjamin, W., Borish, I. Borish’s Clinical Refraction, Butterworth-Heinemann, 2006.
Headway: the Brain Injury Association: “Treatment and Recovery.”
Lee, Andrew G., et al. Curbside Consultation in Neuro-ophthalmology: 49 Clinical Questions, Slack Inc., 2009.
Mayo Clinic: “Traumatic brain injury: Tests and diagnosis.”
Moorfields Eye Hospital: “Anatomy of the eye.”
The Discovery Eye Foundation: “Pupils Respond to More Than Light.”
University of Illinois Extension: “Warning Signs and Symptoms of Common Illegal Drugs.”
University of Maryland School of Medicine: “Anticholinergic or Sympathomimetic.”
Don’t Miss: How Long Can A Cat Live Without Food
Why Does A Cat Sit And Stare At You
Here are 3 common reasons that cats are thought to stare: They may also pair this stare with meows to really get your attention! Many cats are incredibly curious by nature and they always want to know whats going on. It could be just that theyre observing you see if youre going to do anything interesting.
Pupil Shape Reveals Prey Or Predator In Animals
Ever wondered why cat eyes have vertical slit-shaped pupils, while sheep have horizontal bars? A recent study suggests it has to do with their place in the food chain.
Martin Banks from the University of California in Berkeley and colleagues examined the eyes of more than 200 land animals and found their status as predator or prey was correlated to the shape of their pupils. Their findings were published in Science Advances in August.
Don’t Miss: How Long Do Cats Live Indoor
Will My Cat Recover
The prognosis for full recovery depends upon the cause of the anisocoria. In some cases, your cat may require long-term medication to control the underlying cause. If your cat became blind as a result of the underlying disease, it is extremely unlikely that the blindness will be reversible.
Will High Blood Pressure Make A Cats Eyes Dilate
High blood pressure in cats can be a primary or secondary disease. A cat with kidney disease or hyperthyroid can have high blood pressure as a secondary condition. Dilated pupils are a common symptom of high blood pressure.
Vets will check cats blood pressure using a cuff suitable for their leg size. Underlying causes of hypertension, like kidney disease or hyperthyroid, can be diagnosed with bloodwork. The treatment depends on whether the condition is primary.
In most cases of high blood pressure as a primary condition, the veterinarian will treat it with hypertension medications like ACE inhibitors. When hypertension is secondary, the vet will also treat the underlying condition.
Also Check: What Does A Cats Purr Mean
Cats Have Many Reasons For Dilated Pupils
The reasons a cat has dilated pupils can vary from temporary stimulation to medical reasons. Pain can also cause a cats pupils to dilate. You will need to determine whether your cats pupils constrict or whether they stay dilated.
Following up with your vet when you notice anything unusual with your cats health is a good idea. The sooner you get to the bottom of your cats dilated pupils, the sooner you can do something about the situation.
Could A Cat With Dilated Pupils Be In Pain
Cats have strong survival instincts that motivate them to hide pain as much as possible. When a cat hides the fact that it is in pain, it is not as vulnerable to predators. In many cases, a cat in pain wont vocalize much because of it.
However, the downside of the cats hiding pain is that they can suffer severe injuries from being in a fight or getting hit by a car without showing any outward signs. Dilated pupils may be the strongest indicator that your cat is injured.
Sometimes, a lasting result of an injury to the head is a condition known as anisocoria. When a cat has anisocoria, one pupil may be larger than the other. This symptom may occur years after an initial injury.
Read Also: How Big Is A Cat’s Heart
Why Are My Cat’s Eyes Dilated
It is important to note that the dilation of the pupils can be due to other factors, other than light entry. The answers to why your cat has dilated pupils are numerous and can be related to reactions to health problems. Round pupils in cats can also express:
- Excitation: when the animal is very excited and/or nervous, for example, during a game session, it is usual to see it with round or elliptical pupils. However, excitement does not always happen because of positive stimuli, since it can also occur due to stress or anxiety.
- Satisfaction: in situations that produce happiness, the cat also dilates its pupils as a reflex. An example may be when we fill its bowl with food.
- Fear: if the cat has dilated pupils and their eyes wide open it is a clear sign of fear.
- Aggression: cats dilate their pupils when they stare at their prey and prepare to attack.
Although some of the causes that explain why a cat has round pupils are positive, it is important to note that this is sometimes not healthy. If we notice dilated pupils while playing there is nothing to worry about. However, if your cats pupils are dilated because of stress or discomfort, the situation should be assessed. If your animal is feeling anxious, it is your our duty to find the reason why your animal is disturbed and treat it in order to restore emotional stability.
Types Of Pupil Size In Cats
Over the years the domestic cat has been evolving and adapting some of its natural habits. One example of this is its hunting behavior. Due to the dangers that used to lurk, the ancestors of the current cats were nocturnal animals that took advantage of the darkness of the night to feed themselves and at the same time, protect themselves from possible predators.
This was greatly thanks to the anatomy of its eyes, which provides this animal with excellent night vision. For this reason, the feline dilates the pupil as much as possible in order to favor the entry of light. In addition, in the eyes there is a tissue called tapetum lucidum that, in a summarized way, allows for the the eye to absorb and retain light before reaching the retina. This guarantees much sharper vision at night.
During the day, a cat contracts its pupil and keeps it more or less closed depending on the amount of light that there is. Thus, in general, we find the pupils of cats appearing in three different forms:
- Vertical pupil: it is contracted to avoid an excessive entry of light which can be damaging to the eye.
- Elliptical pupil: partially dilated.
- Round pupil: this happens when a cats pupil is totally dilated, mainly, in spaces or schedules of low light.
Don’t Miss: Is Wet Cat Food Better Than Dry
Can A Cats Eyes Stay Dilated Because Of Cancer Or Tumors
According to PetMD, one of the most common causes of eye cancer in cats is uveal melanoma. These tumors form in the colored part of the eye known as the iris.
In many cases, these tumors initially start out benign. However, as time progresses, they might become malignant and spread to other parts of the body. The instances of these tumors spreading to other parts of the body may reach 63%
A cat may develop secondary glaucoma in an eye that has one of these tumors. Glaucoma is a condition that causes high eye pressure. Besides interfering with a cats vision, this condition may be painful for the cat.
A dilated pupil in the affected eye is one of the most common symptoms, along with changes to the iris color, dark spots, an irregular iris, enlarged eyeball, and blindness.
Vets can diagnose this cancer after an ophthalmic exam, with additional testing including a blood panel, X-rays, or an ultrasound. The eye may be removed, depending on the severity of the tumor.
What Else Might I See With Anisocoria
In all cases of anisocoria, the pupil in one eye will be bigger or smaller than the one in the other eye. In some cases, that might be all that you notice. In other cases, depending on the underlying cause, the white part of the affected eye might be red, the cornea might be cloudy or bluish in color, there might be a discharge from the eye, the eyelid on the affected eye might be droopy, the cat might be squinting or rubbing at its eye, or the cat may be less active than usual.
Don’t Miss: Why Do Male Cats Run Away
Cat Sitting Like A Loaf Meaning
Sitting like this is similar to folding yourarms in front of your chest. Sometimes, this is the comfiest way to stand, e. G. If you dont want to dangle your arms by your sides. This simple explanation is the most likely reason your cat is loafing. Its likely comfier for your cat to lie on its side. But loafing is a compromise between being entirely at ease, and being.
Dewhirst: Cat’s Enlarged Pupil Needs Immediate Evaluation
Dr. Dewhirst,
I noticed today that my cat’s right eye has a very large pupil; the other eye looks normal. He has had no problems, but has been losing weight. What can cause one eye to do this?
Diane
Diane,
I believe diseases of the eye must be taken seriously because the eye is such a fragile organ. Problems that cause a dilated pupil often affect vision, sometimes leaving irreversible damage. I recommend you have your cat evaluated by your veterinarian immediately, and it may be necessary to consult a veterinary ophthalmologist.
The pupil, or iris, is a part of the eye that contracts and dilates in response to light. The iris opens when light levels are low to help provide more information about the animal’s surroundings, but when the environment is bright the iris constricts. Mydriasis is the term used to describe a permanently dilated pupil.
Mydriasis can affect one, or both eyes. There are two main categories for pupil dysfunction, primary problems with the iris tissue itself and secondary mydriasis due to other factors and diseases. Possible causes and outcomes vary depending on whether one, or both, eyes are affected, and if vision is lost or intact.
Leading causes of unilateral mydriasis are glaucoma, toxic exposure, infections, drug reactions, nerve dysfunction, tumors, hypertension, trauma, and retinal damage.
The pupils can also become dilated following an injury to the eye. The lens can luxate, or move forward, and interfere with the iris’s normal movement.
Also Check: Why Does My Cat Lick Me All The Time
What Types Of Dilated Eyes Can They Have
What does the pupil do exactly? Its function does not differ too much as that of human pupils. A cat’s pupil also functions as a regulatory agency that adjusts the amount of light that enters the felines eyes.
- A cat’s pupils take two forms: dilated and constricted. Both mean two different and opposite things, very much like how different they look when it comes to its shape.
- A constricted pupil looks like slits very much like that of a snakes eyes, or it is relatively smaller compared to a dilated pupil.
- A dilated pupil, on the other hand, looks rounded and enlarged. Filling almost the entire outline of the eyeball.
What Is Anisocoria In Cats
Anisocoria in cats is defined as a significant difference in the pupil size of each eye.
The function of pupils is to control the amount of light entering the eye. A cats pupils do this by getting wider or narrower in response to changes in the brightness of their environment.
When a cats pupils do not dilate or constrict appropriately, it can indicate a problem in one or both eyes. The abnormal eye may have either the smaller or bigger pupil, depending on the cause.
Don’t Miss: What Temperature Do Cats Get Cold
How Cats Get Their Eye Colour
Curious about cat eye colours? you are on the right page, read on. Cats eyes are so hypnotic in their beauty. every stare is like a hook to quote the ray stevens song cats eye. There is just something about the way they glimmer, something bewitching about those slitted pupils. The logo for the broadway musical cats is a pair of golden cat eyes. A marble with a swirling stripe is called a cats eye.
Stephen King wrote a spooky anthology story called cats eye about a heroic cat who saves his young mistress from an evil troll. The final scene in the epic music video thriller is a close up of Michael Jacksons face with feline eyes as vincent price laughs evilly. Just how do cats get those dazzling eye colours?quick navigation.
Like any other animal, a cats eye colour is determined by genetics. Different genes mean different levels of melanin, the amino acid that controls pigment in the eyes, skin and fur. Melanin comes from melanocytes, the number of which determines the cats eye colour. Wild cats in temperate regions such as lynxes and bobcats typically have hazel eyes. It is very common for feral cats to have hazel eyes as well. However, the eye colour of domestic cats can vary from blue to green to yellow, orange and a copper tone mistook for brown.
An Excited Or Playful Cat May Have Wide Dilated Pupils As They Get Ready To Play
However, fear or surprise could also lead to the same result. Changes that occur due to excitement or fear should be relatively short lived. As the cat relaxes the obviously large pupil should return to a smaller size. A young playful cat is much more likely to display wide pupils because of excitement or fear as they are naturally more inquisitive and playful. A more relaxed sedate cat may not often dilate its pupils due to excitement.;
Don’t Miss: What Is The Healthiest Cat Food
Diagnosing The Reason For Your Cat’s Anisocoria
Most eye workups will start with three basic tests: A Schirmer tear test, fluorescein stain, and an intraocular pressure test. A Schirmer tear test will check the ability of your cat’s eyes to create tears. There are certain disease processes that will inhibit tear production. Your cat’s eyes will actually try to compensate but instead of tears they may produce a thick, sticky discharge. All this to say, you may think your cat just has funky tears when in reality he has a lack of them! Staining the eye with fluorescein dye can illuminate any ulcers on your cat’s cornea. The stain will collect in the ulcer itself so that, even when excess stain is flushed out of the eye, the stain will still fluoresce under a black light. Checking your cat’s intraocular pressures can check for glaucoma as well as uveitis. If your cat has glaucoma in one or both eyes, they will have higher than normal pressures. If your cat has uveitis in one or both eyes, they will have lower than normal pressures. Rest assured, veterinary medicine doesn’t check eye pressures with the dreaded ‘air puff’ test that is common in human ophthalmology.;