Why Are My Cat’s Eyes Always Dilated?

Why Are My Cat’s Eyes Always Dilated

Just like with humans, your cat’s eyes can speak volumes about their mood and general state of health. 

When you look into their eyes, you might notice that their pupils are slightly dilated, and this is usually normal. However, if their pupils remain dilated and do not seem to react to changes in the light, this could indicate a serious medical issue. For a devoted cat parent, this can be really frightening – especially if you do not know the underlying problem.

You may have landed on this article due to exactly that question: “Why are my cat’s eyes always dilated?” Here, we will discuss some of the common reasons, and when you should take the symptom seriously. 

What causes a cat’s eyes to dilate?

Cat’s eyes dilate for several reasons, most of them normal and healthy. Just like humans, the dilation of their pupils is a natural reaction to changes in darkness and light, and also to fear and excitement. It can also be a sign of arousal, and cats’ pupils may dilate when they are trying to show affection.

Aging can also cause a cat’s eyes to dilate. This is due to the weakened ocular (eye) muscles, allowing the pupil to widen more than normal. If your senior cat has a medical problem, one of the first symptoms you might notice is that one of the eyes becomes constantly dilated.

Your vet can diagnose the cause of the dilation and recommend the best course of action. In some cases, there may be a simple cause and the problem can be easily corrected.

Pupil dilation can be a sign of illness, trauma, or injury. As their guardian, you must regularly monitor your cat’s eyes and take them to the vet if they appear to be dilating more than usual. Fortunately, in most cases, dilation is only temporary and should resolve itself in a few minutes or hours. If not, then it is time to take your cat to the vet for a check-up. 

In the most serious cases, dilated pupils can be related to a life-threatening medical condition such as cancer or tumor growth. While your vet might recommend additional tests or treatments, the prognosis for these diseases is usually poor. Hence, it is extremely important to be aware of any changes in your cat’s eyes and seek medical attention as soon as possible.

Why are my cat’s eyes always dilated?

1. Nutritional deficiencies

Cats may have dilated pupils due to a nutritional deficiency, specifically a lack of taurine and vitamin A. This can be caused by eating poor-quality cat food that lacks the necessary ingredients for a healthy diet. Not only does this affect their eyesight; it can also have an impact on their digestion and cardiovascular health. 

If you are noticing a change in your cat’s eyes, you should consult a vet immediately to ensure that they are getting the proper nutrition. You should always choose high-quality food for your cat so that they get the vitamins and minerals they need for good overall health. Investing in quality food can save you money in the long run, as it will help reduce the chances of health issues in the future.

2. Blindness

Cats can experience blindness due to various illnesses. Kidney disease, eye infections, and feline herpes virus (FHV) can all lead to consistently dilated pupils and eventual blindness in cats. 

If you believe your cat has a problem with their eyesight, there are some signs you can look out for. These include disorientation, acting clumsy, and bumping into objects. If you notice any of these signs, you must take your cat to the vet right away. With the right diagnosis and treatment, cats can often regain their sight or at least improve it. However, know that there are no treatments available for permanent blindness. 

3. Permethrin poisoning

Permethrin, a chemical used in flea and tick treatment products, can be extremely toxic to cats. If a cat ingests permethrin, symptoms can vary and might include dilated pupils, muscle tremors, drooling, and seizures. If a cat is showing any of these symptoms after being exposed to permethrin, it is essential to seek immediate veterinary care. Without treatment, the cat can suffer permanent damage or even death. 

If you suspect your cat has been exposed to permethrin, the best course of action is to call your vet and take the cat in for an evaluation. In some cases, the vet may need to induce vomiting or give the cat activated charcoal to help absorb the chemical from the stomach. If the cat’s symptoms are severe, they may need to be hospitalized to receive intravenous fluids and medication to help counteract the poisoning.

4. High blood pressure

High blood pressure (hypertension) in cats is a serious condition that can have dire consequences. Dilated pupils and lethargy are two of the symptoms of feline hypertension. Its common underlying causes include hyperthyroidism and kidney disease. To manage the symptoms, veterinarians usually recommend a class of drugs called ACE inhibitors for cats with high blood pressure. 

However, it is important to also treat the underlying condition to ensure long-term success. 

If left untreated, high blood pressure can have severe consequences and become life-threatening. Hence, being aware of feline hypertension is important so you can take the necessary steps to prevent it. Be sure to work with your veterinarian to develop a comprehensive plan and preventative measures.

5. Feline leukemia

Feline leukemia is caused by a virus that affects the cat’s white blood cells, making them unable to fight off infection. Aside from dilated pupils, other symptoms of feline leukemia include weight loss, lack of appetite, gum problems, and diarrhea. If your cat is exhibiting any of these symptoms, it is important to take them to the vet as soon as possible. 

Your vet will be able to diagnose feline leukemia through a blood test and recommend several treatments to help manage your cat’s symptoms and improve the prognosis. While there is no cure for this disease, proper management might help improve your cat’s quality of life.

6. Dysautonomia

Dysautonomia, also known as Key-Gaskell Syndrome, is a debilitating condition that commonly affects younger cats. The disease primarily targets the nervous system and can have a severe effect on a cat’s bodily functions, including the eyes. Cats affected by the disease will lose control of their eyes and this will cause them to stay dilated.

Other symptoms of dysautonomia include vomiting, diarrhea, and dehydration. While there is no cure for the disease, early diagnosis and treatment might help alleviate symptoms and prolong your cat’s life. 

7. Eye cancer or tumor

While eye cancer is rare in cats, some might acquire the disease, specifically if they have uveal melanoma. This cancer starts out as a benign tumor, but can quickly become malignant and spread to other parts of the body. 

Cats afflicted with uveal melanoma may also develop secondary glaucoma, as well as changes in iris color, an enlarged eyeball, dark spots on the eye, or even blindness. Unfortunately, this type of cancer is very difficult to treat, and the prognosis is often not good. That is why it is so important to have regular veterinary check-ups for your cat and to be on the lookout for any suspicious changes in their eyes. 

Contact your veterinarian right away for an evaluation if your cat seems to display unusual eye changes, including frequent dilation. Remember that early detection and treatment can make a big difference in the outcome, so do not hesitate to take your cat to the vet if you have any concerns.

8. Anisocoria

Anisocoria is a condition in which one of a cat’s eyes is constantly dilated, making it appear larger than the other. This condition can be caused by a number of things, including glaucoma, head trauma, corneal ulcers, and exposure to toxins. 

If the cause of anisocoria is a head trauma, then the dilated pupil might be temporary and should resolve on its own. However, it is still important to have the cat seen by a veterinarian to ensure that the underlying injury is properly addressed. 

While anisocoria can be uncomfortable for the cat, with proper treatment it can be managed, and the cat can continue to live a happy and healthy life.

Do cats with dilated pupils struggle with pain?

Cats are notoriously silent about their pain, and that is because they do not want to advertise when they feel vulnerable. This is part of their survival strategy to make them less attractive to predators, who are more likely to target animals that are already injured or weak. Cats will also mask their pain by adjusting their posture or not moving around as much. 

Unfortunately, their incredible ability to hide pain will also make it challenging to tell if they are hurt or struggling with a disease. Hence, looking out for signs such as changes in behavior or appetite will help to diagnose your cat in a timely manner. By understanding their survival strategies, you can better recognize when your feline is in pain and take the appropriate steps to help them.

As mentioned, one of the strongest indicators of pain or trauma in cats is dilated pupils, which can be seen even when they are attempting to conceal their symptoms. Since cats tend to be very good at hiding pain, it is important to be aware of these signs, especially if they also show sudden changes in behavior. 

If you notice that your cat’s pupils are dilated for no apparent reason, it is important to take them to the vet to be checked out, as it could be a sign of injury or illness. Paying attention to your cat’s behavior and being alert to any signs of pain or trauma can help ensure that your beloved feline lives the longest, happiest life possible.


Your cat’s dilated pupils are usually a normal reaction to varying light conditions. Dilation also occurs if the cat is overstimulated, afraid, or stressed. However, consistent dilation of the eyes without any apparent reason might indicate an underlying illness. 

Cats are generally excellent at hiding their pain, so it can be challenging at times to help them when they are struggling with an injury or a disease. So, if you do notice unusual dilation of their pupils that does not seem to resolve on its own, this should warrant a trip to your veterinary clinic.

Image: istockphoto.com / Sonsedska